Looking for imput into the fuel (#) starvation problems on track.

In LH sweepers with 3/4 tank or below...that are 10sec or longer....the car (#) bucks and snorts and cuts out. Sometimes it throws a missfire code...other times it doesn't.

I was watching the Grand Am (#) Cup race (#) today and it seems that a few cars (#) are having the same problems.

Anyone have any ideas for a fix that works?

Go to dual pumps and return type fuel system??

The only problems I can see are Evap ZControl system freaking out............

I have noticed that it seems to be doing this a lot more this year than last. Some may be due to stickier tires (#) and better driver :D: Any other ideas ???

I am getting them to check the fuel pump and tank valves for defects...but I'm sure after that it will be my problem to fix :(

Speedsource seems to have a fix for this problem, but I don't know what that fix is. This blog http://www.grandamadventure.com/GA_main.html makes mention of sending their tank to them to correct the starvation problem.
I run into the same problem myself.

I thought they had a fix until the race today :( Now I'm not sure. Both the cars had fuel problems.....and they were built by Speedsource.

Could be vapour lock problems cause of the heat though...it was 105 degrees in the shade today in Phoenix

Run a search on "fuel starvation" There are at least a couple of threads on the matter, if not here then in the racing forum. My wonder has been more people haven't complained about the problelm ~ I guess not that many are tracking their cars that hard. I was totaly unsuccessful in trying to get hold of some one, either at a dealership or with Mazda who would even acknowledge the issue, much less offer any solution. IMO, the biggest failure in an otherwise exceptionally great bang for the buck car. Running out of gas in a high speed sweeper with some one hanging on your tail, and not expecting you to slow isn't the best of feelings. Makes one worry abit about other really important fluids ~ like oil. But so far no issues with that. I guess that would be a self correcting problem. A couple of hundred claims, and the accountants in Mazda's warranty department would "zoom-zoom" down on the engineerig guys in short order :-)

SpeedSource has a solution. BTDT. Required sending Sylvain a gas tank, but last I spoke with SpeedSource, they were not very interested in dealing with anything but race cars. Didn't want the responsability of handling DOT street applications. PM me if you need more info. I'll be at Miller MotorSports in Utah with the Rx8, most of this week till the 24th and may not have very good email access.

Cheers.
mike

http://www.rx8club.com/showthread.php?t=83108&highlight=fuel+starvation

I did search...and TeamRX8's thread was the only relevant one. It's very difficult to get to info from Speedsource when they are racing :(

Im betting on Vapor lock myself. I watched the race as well. I think like weve seen with the Vegas cars, the rotary just doesnt like temps of 115 and over.

I seriously doubt it's vapor lock given the flowrate under racing conditions

Grand Am is still limited to certain rules which you are not obliged to follow. Your best bet is to have a mini-tank between the engine and the main fuel tank, but this requires reworking the fuel system to pump low pressure into it and then have the high pressure main pump feed the engine from there. It needs to be sized large enough to sustain the engine under the longest starvation period that the main tank may experience.

I've had that problem, but only when it got down to around 1/8 tank. I seem to remember reading something about a low pressure pump located in the gas tank. If it's really vapor lock that caused it for the Grand Am folks, that should be easy enough to fix.

I kinda doubt the vapor lock too...at close to 60PSI I doubt that will happen.

I have though of going to a "surge" tank type setup...but with the returnless system how would it work?? I was thinking I could use a low pressure pump to feed a tank that the OEM setup fits into??

What about using a one way valve with a 2litre tank inline on the HP side...as long as the tank can handle the pressure it should work???

here's some ideas:

http://toyotaperformance.com/surge_tank.htm

http://www.velocity-of-sound.com/velocity_of_sound/surge_tanks.htm

try googling "fuel surge tank" or "fuel surge "pot" for other options

again, Grand Am is limited by the rule allowances, you are free to do whatever works ...

This was taken from the blog.
-----------------------------------------------------------------------------------------
The car handles fairly well on track, and we are getting some much needed practice, but unfortunately we discover that the fuel system problem that caused our 30 minute "pit stop" at Daytona still isn't fixed. This is despite the fact that back in his shop Doc has been working on the fuel system, and swapping out every moving part or electrical component that could cause the issue.

The RX-8 fuel tank is really like 2 fuel tanks - a passenger side and a drivers side, with this hump in the middle that goes over the drive shaft tunnel, kind of like a pair of saddle bags. The fuel pump itself sits inside the tank on the drivers side (indicated by the number "3" in the diagram above). It has a scavenging tube which crosses over the "hump" in the middle, and allows it to siphon fuel from the passenger side. It seems like we can only use about 1/2 the fuel in the tank before the fuel pressure drops and becomes inconsistent - so our first inclination was that the siphoning tube was clogged or disconnected. So we remove a cover on the passenger side of the tank, and we can see with our own eyes that side of the tank is bone dry (which is good). In fact, all of the remaining fuel is on the driver's side of the tank where the fuel pump sits. How strange. We try different fuel pumps and that doesn't fix it. So we are back to the drawing board, but this time we have at least eliminated a few culprits.

(Further down)

He reports back that the fueling problem is fixed. Doc came up to Wilmington and replaced some more of the hard plastic components inside the fuel tank, and we can now draw down to about the last 2 1/2 gallons in the tank before we get fuel starvation. I'm not sure that is good enough, though, to make it through a 2+ hour race on one fuel stop. Our fuel mileage is pretty abysmal and it looks like we can only go about 57 minutes max before we get bad fuel starvation. And I suspect that number may be optimistic.

How will this work for the returnless system though? This would work well if there was a fuel return....I really don't want to change the fuel rails etc...if I don't have too.

Have you seen the intake side of the OEM pump that is in the tank...could it be retrofitted with an in tank surge system?? using another LP pump??

I talked to Mark about that and he doesn't have any idea what Doc did.

I know it can be fixed with a surge tank and a return type modification to the fuel system...but Crikey....this is BS. It would be a massive rework of the fuel system to do it that way. This is on a performance sports car.... That is still under warranty :(

MAZDA..WTF can be done...

Haha if speedsource cant solve it after two seasons........................................... ......
________
Wellbutrin Lawsuits (http://www.classactionsettlements.org/lawsuit/wellbutrin/)

They have rule constraints that we don't have ........but they must have tried a lot of options. It would be nice if we could rule out the options that they have tried to save some time

They have rule constraints that we don't have ........but they must have tried a lot of options. It would be nice if we could rule out the options that they have tried to save some time

do you have a fuel pressure gauge on it? there have been some pumps that run fine then on certian occasions drop down to 15 psi...

it was one of the tests they did on my car...

beers :beer:

Has anyone removed the fuel pump and the pickup units from the tank......

I am going to pull it apart and see what can be done to alter it .....and I just wondered if there were any strange problems with the RE/RE that I should expect...ie gaskets, difficulty getting at things etc

Thanks

Has anyone removed the fuel pump and the pickup units from the tank......

I am going to pull it apart and see what can be done to alter it .....and I just wondered if there were any strange problems with the RE/RE that I should expect...ie gaskets, difficulty getting at things etc

Thanks

belive it or not we had someone do it in the middle of a sonics parking lot...
we were at a local meet, and a clamp had come loose on his new hiflo pump...

it must not be difficult and i doubt if he did that gaskets are an issue.

beers :beer:

Let us know what you find out.

I'm interested in a solution.

Good Luck.

I saw that race and thought it was the newbie drivers from Japan. However you said speed source already modified the tanks :(

OK..I pulled both inspection covers off the fuel (#) tank.

Passenger side has a fuel pickup (#) that feeds a venturi driven suction that works off the fuel discharge from the pressure regulator that is built into the fuel pump. This seems to be really effective, as the passenger side of the tank was bone dry at 1/8 tank. All the fuel was in the drivers side tank :)

Drivers side has the fuel pump..that is built into a small cuplike" tank"...with integrated fuel filter (#), pressure regulator, and venturi for the transfer tube from the passenger side.

This tank cant hold much more than 2 cups of fuel. This assembly is built into a "sliding" retainer that holds the pump/pickup assembly against the bottom of the tank.

So here's the problem......why does the pump run out of fuel??

MY best guess.....
If the fuel is all sloshed into the passenger side of the tank under high fuel flow and hard LH sweeper...it seems that the siphon can't keep up to fuel demand??? If the pump isn't getting enough pressure to activate the venturi...the siphon stops...and the pump runs out of fuel cause it is all in the passenger side.

Problem with this theory.....my car (#) will run out of fuel at 3/4 tank in really hard LH sweepers. At this level there should still be fuel for the pump to have fuel in the drivers side of the tank.

Does anyone else have any ideas???

I need to get a hold of Sylvain at Speedsource and see if they can help with the fix..........Problem is I really don't want to send my tank all the way to Florida from Canada if I can help it :(

Another idea...

Some of the E36 M3 Bimmers had this problem with a very similar tank. They installed another OEM style pump in the siphoned side of the tank...so that there is a pump in both sides.

I think that the passenger side hole and tank is the same as the drivers side....


Maybe we could install an OEM pump into the passenger side...and T the supply lines so that both pumps supply the fuel system with fuel.

The 12V supply to the stock pump could be used to drive a relay for the new pump that is wired to the battery directly

Anyone see any problems or complications with this??

First problem I can see...

OEM fuel pump runs at 2 different voltages/speeds depending on load....

What would the best way to wire this be?? Can the stock system with the resistor altered voltage run both pumps with a bit bigger fuse 20A? or would I be asking for wiring problems? Could the additional pump run on high..or low speed all the time..and not affect fuel delivery?

note.

check the fuel pump wiring harness. i know of one that went bad....

beers :beer:

Thanks Swoope...as far as I can tell everything stock is working OK.

I have checked the fuel pressure..and driven the car with the guage on for a while. I have wiggled the harness and checked the connectors in the tank..they all seem to be OK.
I guess the G loads from the new tires is enoug to cause almost total fuel transfer to the passenger side when the tank is between 1/2 and 3/4 full.

This problem has to be solved 100% for me before I can go FI.....it would be an engine ending problem under boost :(

I haven't had problems with LH corners. I do run into starvation on RH's when the tank is less than 1/2 tank. From the description on how the tank and pickup is designed, I don't understand how this could happen.

You must be pushing extreme G's in the LH corners.

I haven't had problems with LH corners. I do run into starvation on RH's when the tank is less than 1/2 tank. From the description on how the tank and pickup (http:///#) is designed, I don't understand how this could happen.
I don't know about right handers....maybe the pump pickup can't get any fuel...and when the "cup" runs out it causes the same problem??

In LH..the fuel (#) is pushed to the passenger side tank.........From there I don't know what is the biggest problem....either the suction transfer fronm that tank won't transfer fuel fast enough....or the pump runs out of fuel due to the high fuel requirements....then the venturi quits..and the transfer stops??

I am going to try the pump in the R side port and see if it fits.......if it does I'm going to try the 2 pump setup and see how it works. Worst case scenario I have a spare fuel pump (#) :)

Just took out the pump and the cover on the passenger side.

Both sides are the same....so I'm going to order a pump and see what happens.

I have a track day next week...so I hope I get the pump in time to try it and see if it will work

Only two days to get it done!

Won't get the pump til earliest Wed PM....so I will have to wait til the next track days.

I'll just take my fuel jugs and keep it really full :)

OK...been working on this a bit today...

Got the fuel pump, and all the wiring bits...went to the wrecker for some OEM bits...the plug on a Protege tank is the same as ours.........makes it easier to get the plug :)

I wired the pump to the OEM pump circuit...and installed a switch in the console by the Accessory plug. I figured why have this on all the time when I only need it on the track.

I got looking at the tank from underneath and couldn't find an easy way to run a fuel line that didn't get too close to either the exaust or the drive shaft. They didn't leave a lot of room in there.

What I did find though was that the unibody has a large x-brace that is the major structural member that goe across just ahead of the fuel tanks. It has some 3/4" access holes in it...and it is open all the way across the car. End of a search for a place to run the fuel line. It's in it's own little armored tunnel :D: All it took was a few minutes with a fish tape and I was good to go.

Ran into a little snag though....didn't have enough high pressure fuel line to run it the car :(

Couldn't find any today either...so I guess I'm using the wifes car until Monday....she'll be impressed.

All I need to do now is install the fuel pump...and rig some type of pickup for the suction siphon in the Right hand tank that will still transfer fuel to the Left side when the pump is not on ( like OEM ) and re-wire the fuel level sensor in that side of the tank.

So far I'm into it for about $180... Just won't know if it will work....guess I won't know until I hit the first really fast LH corner :D:

It can, and has been fixed with the addition of a small auxillary pump in the fuel tank. Speedsource's solution was for, at least when I contacted them, ".... track cars only..."

Speedsource also advised that their solution would cost you the use of the cars fuel gauge ~ but there's a work around for that.

I was at Heatland park last weekend to watch a couple of friends competing in the SCCA Spec Miata series and Mazda open wheel "platypus" cars. There were a couple of 3 or so Rx8 running in T3. I asked one of the Rx8 drivers if they did anything for the fuel starvation issue. Somewhat to my surprize, he said they weren't allowed under the SCCA rules to modify the fuel tanks, so ..... they just make sure to run with an extra 5-6 gallons minimum in the tank. My guess is T3 must set some minimum weight limit, and the any particular race , test or qulaifying session is never long enough to make drawing the tank down below 1/3rd an issue. I guess the extra 5 or so gallons that has to be carried in the tank is simply chalked up as "dead" weight (? @ 5x7=35#) needed to maintain minimum weight for the class. Go figure

I completed the install today.....no leaks, the fuel guage works and the fuel pressure stays basically the same with both pumps on :D: For all intentions..the install looks totally stock. A casual observer would not be able to tell that this is done. The mechanics at the dealership came out to look and didn't notice until I pointed it out.

I won't know how it works on the track...but it will have twice the reserve capacity( two pumps, with the small surge built in) and twice the pump output capacity.

There will be no problems supplying more than enough fuel to max out the 5/16 stock fuel lines

I figure that all in all it cost me about $200 to do this. The pump was $160, and the other assorted bits from the wreckers,switch, wire, HP fuel line (4 ft) and hose clamps was less than $40.

I hope this solves my problem......next dry track day will tell:)

Me too, thanks for the update.

I completed the install today.....no leaks, the fuel guage works and the fuel pressure stays basically the same with both pumps on :D: For all intentions..the install looks totally stock. A casual observer would not be able to tell that this is done. The mechanics at the dealership came out to look and didn't notice until I pointed it out.

I won't know how it works on the track...but it will have twice the reserve capacity( two pumps, with the small surge built in) and twice the pump output capacity.

There will be no problems supplying more than enough fuel to max out the 5/16 stock fuel lines

I figure that all in all it cost me about $200 to do this. The pump was $160, and the other assorted bits from the wreckers,switch, wire, HP fuel line (4 ft) and hose clamps was less than $40.

I hope this solves my problem......next dry track day will tell:)

great job!!!

beers :beer:

I just came across this thread and wanted to give a bit of warning with the fuel system setup that you have currently installed (assuming I understand what you did correctly).

How exactly is the 2nd OEM pump plumbed into the fuel circuit? Do you have both pumps feeding to a T-joint on the outside of the tank and then to then feeding the engine? If this is the case I would advise against this.

This would work providing that both sides of the tank drain at the same rate and there was no sloshing of fuel from side to side. We know this isn't the case. If it were we wouldn't be seeing a starvation problems.

Knowing that during cornering we do not have any fuel in one side of the tank we know that the pump will not be picking up fuel on that side. If this is the case the pump will burn up fairly quickly. The carbon commutator and brushes of the pump need the fuel flowing past them to provide lubrication and cooling. Without any fuel present the pump will get very hot and seize. The pump will no longer work and you may have caused more starvation problems then before. Not to mention the fact that a large heat source is now inside your fuel tank.

If you are going to run 2 pumps in the tank. Hook the pump up to some type of logic so that the pump will shut off when there is no fuel present. This can be done by tapping off of the sender gage. I have seen it done before but not sure about the details.

Another option is to put a diaphragm type pump on the secondary side (passenger side of the tank). Diaphragm pumps can run full time without generating lots of heat and burning up. The diaphragm pump is not intended to supply the engine with fuel directly. It would only be present on the secondary side of the tank to transfer fuel to the reservoir on the main side. This would aid the venturi system that is already in place.

Sorry for the long post. Hopefully it helps. I don't post much but you guys finally have a problem that I can help with and I thought I add what I could.

Thanks for the feedback. I have put a switch on the circuit...and only plan on running the pumps at the track when there is above 1/3 tank of fuel... I left the OEM siphon in place for emptying the passenger side of the tank like normal when the second pump is off. I will see how this works long term. I am aware of the problem with the pump running dry and overheating

I too have had this problem on high G LH turns. Once I had my suspension and R compunds on and the G's went straight up. In turn 5 at roebling -if I am in 3nd gear at 7.5--8K at the apex she flat dies, like you have turned the ignition off, and it lasts to the exit IF I AM AT FULL THROTTLE only. If I take it in 4th--rpms at 6K or so-- even at full throttle--no issues at all. (i was just experimenting --it is a faster turn for me in 4th than in 3nd). Still this is of concern. If the car is at high rpm and runs out of gas--it doesnt do this engine any good(I am also running a pre mix-- still have the MOP). this is the only place i have had a problem
olddragger

Mine didn't do it either till I got the wide ass sticky tires :)

It wasn't a problem at all on the stock setup...just didn't pull enough G's in the corners

The thing i don't like is that the cut off is so fast that it makes the rear end break out......not a nice thing in a long 90MPH sweeper going into a blind apex corner that is a cement wall :(

I hope this will work...time will tell

loose rear end does cause a lot of memories------:) But you are right it is a sudden cut off , no skip, hiccup or anything--just DEAD and then it is all the way back ON when it comes back. You would swear it is somehow an ignition thing rather than a fuel problem--weird.
But we are hauling ass---right!
OD

Does yours set a missfire CEL....mine does....( second time around :D:) and then it doesn't want to run normal until I reset the ECU. It was so bad on the last dry track day that I had to stop driving part way through the last run group of the day... That really pised me off..

man-- nope mine doesnt throw a code, no cel--just about a 30-40 yard complete loss of power. Really made my passengers eyes open up and grab the Oh S--- handle!!I think HE threw a code. You may need to gear down and use a lower final drive that brings the rpms down?--more dialed in? Just guessing here. Are you over 7K or so when this happens?
Olddragger

Oh i hear that speedsource doesnt use over 8K in their cars.
OD

It is usually 7-8K at about 80 MPH in a long sweeper. just before you need to upshift to a higher gear. I have tried shifting earlier...but it doesn't have any power then and I loose a lot of speed in the corner.

The instructor almost had a coronary as well when it happened the last time......... just caught the ass end as it stared to come around :D:

is it fun to scare an instructor???

i bet it is..

beers :beer:

Scaring them is one thing...I had one throw up in a full face helmet at one track day.

I registered late and they put me in a beginners group.....the instructor lost it in a corner:Eyecrazy:.

Got most of it on his suit.....but he was gone for the rest of the day :D:

They moved me up to a faster run group after that.................without an instructor

lol--bet he remembers you. Swoope anyway to go to 17's 40 series r's or 18 --35 series r's on your car so you can possibily go into the turns and exit the turns in 4th? My car behaves the same way full power on 3nd at 7.5-8k(things are happeing fast then--not really watching the tac that much) in 4th --no problem and it ended up being faster for me. Cant go faster until you can upshift!
olddragger

I have started suffering from this issue too. I am on RT615s and expereince it starting even with a full tank. It happened out of the blue on a track I had been to before with zero problems so I am concerned it is a problem that gets worse with time.
Dannobre - I would like to get more details on your solution. Can I contact you? you can PM me if possible...

Anyone else try anything? Is it possible teh stock pump gets weak? My car has 48K on it now. Maybe just a new OEM pump fixes the problem for the next 40K miles?

I would change out the OEM pump...it's a relatively cheap thing to try , and it will probably work. The second pump on mine is only needed below 1/4 tank...I would probably not have done it If the new stock OEM pump would have gone in before all the rest of the stuff :)

one thing to keep in mind, and this is where it gets confusing to me, with increasing options of mods giving honest increase in power plus R compunds,Plus suspensions,plus drivers getting better--all equals to the need for a stronger fuel delivery system. Once experienced this is an issue I dont ever want again--can be real dangerous on the track.
So which will it be:
1- Replacing the stock pump may solve this problem for a limited time and if no more mods happen to the car etc. cost approx $180-200?
2- go with Mazsports plug and play mod and have no worries up to 400hp--cost approx $400 after core rebate. approx $200 more for no more worries at all.
3- go with a Dannobre oridginal remedy and also it seems no more worries--cost unk but probably less than Scott's.
HMMMMM.
olddragger

Scott's is $599 plus a refundable core charge.

It might not be the best for a NA car without tuning...as it uses a rising rate pressure regulator. The stock fuel system might not like the variation in FP when it doesn't expect it.

Changing the FP results in mixture changes.......Youi would have to ask Scott if it will work NA with the stock ECU. I'm sure it will work awesome with the IntX and some tuning

I would change out the OEM pump...it's a relatively cheap thing to try , and it will probably work. The second pump on mine is only needed below 1/4 tank...I would probably not have done it If the new stock OEM pump would have gone in before all the rest of the stuff :)I am going to change the stock pump with another OEM unit. If that fails to fix the issue, I will use the old pump in addition to the new one I guess. Thanks for your response.

good point dannobre--i also realized after i point out that scotts mods really has not been proven to fix this issue. its more of an upgrade for fi.
After all is said and done --you know i am not totally convinced that my problem is fuel starvation. I mean with my pr0blem there is no hiccup, no skip, no sputter, the engine just dies as if the ignition turned off and then no sputter, no hiccup, no hesitation--she is back on full power. Same place on ONE track and I know I am pulling just as many G's in other left hander's. it is really very strange. Before I do anything radical here I have to do more research.
olddragger

That's exactly what mine did...it just died...and then came back on after the G-load dropped.

Maybe the pump is cutting out?.....It stuttered sometimes as well on less severe corners, and acted more like fuel starvation normally does.

It would only do it on long sustained Lefts at first at 1/2 tank or below. After a while it got worse, and would do it when the tank was almost full.

The new pump fixed it down to about 1/4 tank...and with the second pump Iwas good to almost fumes before it would quit

thanks dannodre--good to know. Mines a little stranger as that is the only corner on any track i have ever had any issues with. even with a FULL tank of gas. The 1st lap was uneventful but from that point on well----
A simple T pickup one on passenger side --one on driver side wouldnt work?
olddragger

There is no real way to add a pickup tube that goes to both sides...esp with the stock setup.

The fuel level system uses 2 levers...and assumes that the passenger side tank is empty when calculating the level on the lower end of the tank from what i can see.

You will see how it works when you pull it out....the passenger tranfer is a siphon from a venturi that is driven by the fuel pressure regulator outfall.

ok thanks for the feedback. i wonder if any of the fi boys are tracking? I havent heard. and if they are what are they doing for upgrades.
oD

Also remember the old dirt track and circle track boys used to build a "false mini surge tank" by putting the biggest dang tube they could find for the gas line--effetively adding in some extreme case 1 gal to their capacity. I would not want to go with that big of a line with an fuel injected car but I was wondering if you just added a bigger line would it not give you enough gas to get through our problem area and then the pump could catch up? Could that be a simple fix for us non regulated track guys?
I like your system--seems more solid than others i have read about--but not ready to go that complex route yet. I have to have a solid system --dont mention it(so I post about it--right:)) but I plan on going with the afsc and with that much on the engine i damn sure i dont want any lack of fuel.
thoughts?
Olddragger

that won't work or fuel injection without a second scavenger-type pump further up stream, once you lose fuel pressure you're done with EFI regardless of the tube size, the NASCAR engines use an engine-driven suction pump to feed an atmospheric carb bowl, what you need is a small reserve tank between the pump and the EFI with an auto air bleed devise, alternatively you could use a small secondary tank supplied by a low pressure pump which then serves as the feed for the high pressure pump but it gets complicated with an in-tank system

Bingo!---thanks team--i complety wasn't thinking of that. Pressure has to be there and if the pump aint sucking fuel --- there will not be any pressure---looks more and more like i too will be doing the bmw fix like Dannobre BUT using Mazsports set up as primary--why isnt anything easy for me---damn.
Appreciate the focus--thinking too hard of a way out.
olddragger

You will probably have to run the regulator different on Scotts...ie without the Vac presure adjustor attached??? The Fuel pressure is designed to rise in his setup when the manifold gets pressurized........

Duh...when I was typing this I answered my own question....no positive pressure = no rise in regulator output.....Double DUH for it being way too early on a Sat morning :D:

seems like we think alike at times:)
i do want to get this sorted out before the afsc is offered.
olddragger
.

I think I have firgued it OUT!
How about a Top mounted baffle inbetween tanks? It would slow the sloshing enough to not allow the starvation issue---wouldnt interfer with filling etc.
Trouble is--how hard is it to crack the tank and do?
thoughts?
OD

Would be hard to do I think.....Speedsource mods the tanks somehow i think.....but they make the fuel guage inoperative at the same time....might not be a problem that is hard to fix.

I can live with OK down to 1/8 tank......

I'm also not totally sure it's a slosh thing...it might have something to do with how the pump pickup works....It might run the "little cup" out of fuel...and be unable to refill it....you would have to look at your pump to figure that out :) I think why my 2X pump works is that it has twice the reservoir before the pumps run out of fuel??

Speedsource won't guarantee the fuel gauge working after their mod. They also have said, at least in the past, they provide the modified tank for track cars/track use only. I can say with careful positioning of the parts, one can retain use of the fuel gauge. FWIW, I can now run the car on the track down to almost the reserve line without fuel starvation. Before, with MPSC and Dunlop SSR 255 and 265/35's x 18's I could, would and did have fuel starvation issues with as much as just under one-half a tank in the car. As fast as these cars chew up fuel on the track, i.e. I'm getting something like > 10 mpg under track, being able to confidently run the car without having to refuel every session is well worth the cost of getting this issue fixed. Having your car suddenly lose power or "surge" then lose all power in the middle of high speed sweepers, with other cars in close proximity to your rear bumper is not something to be enjoyed. It's a hazzard.

I concur--I am not tracking my car until this is fixed. It is very puzzleing. Deductive reasoning list
1: I ran the same track(Roebling) several times before and even let a certified driver take it out and had no issues--even at 1/2 a tank.
2- then a few months later another track w/e and sx's show--controllable by lowering the RPM and throttle position--same track--on the same turn --shown 1st when i had about 1/2 tank
3- i did another track even --this time at road atlanta--no issues even at below 1/2 tank. and we were running hard
4- back at roebling a few monthes later and after the 1st lap --even with a FULL tank on one particular turn(double apex left hander immediatly after a short r hander--i go a DEAD engine for about 50 yards as I am exiting the l hander---nothing i could do would stop this--lower rpm, partial throttle---nothing. But it didnt get any worst as the gas got lower in the tank( i contunied to run-- but when traffic was around i would wave them by)
Never have had this problem anywhere else.????????? So in my case it seems to be a progressive problem.
If it is a cup issue why that one spot when other left handers pull more G's and are even longer?
Since it is a double apex there it is a "sudden" change in direction therefore this made me think of the slosh possibility.
still researching this--scotts system may work because it does convert to a return type system and the pump is stronger. if anyone else has any experiences or solutions please join in.
dannobre your system is the only one i know of that fix's this!
saga continues
olddragger

I would think that the stock pump is crapping out...that's about the same chain of events that mine had.....I thought at the time it was me going faster and pulling more G's..but I think it was the pump. You can solve it by putting in a surge tank....A tank that is inline...pressurized with another pump. That will solve it as well.

I would go with the new stock pump and I think that it will probably work.

I also think that the Mazsport pump should work as well.......but until one of us does it and tests it at the track...back to back with the non-working one, we won't be sure :)

yep. enough said--appreciate your help and if you hear anything else let me know and i will do the same.
od

well damn-- i was checking mazsports fuel pump upgrade and it is more expensive that i thought. I was thinking it was $600 with a core charge of $200 making it a $400 upgrade and that was workable. But a $600 upgrade--I dont think so.
oldragger

I'd like to include myself in the "fuel starvation problems". LH high G corner had me thinking that I was already hitting the rev limiter. I looked at the revs and it was just showing 7k rpm. Bloody hell... it really sends the car into an imbalance especially when the car is in mid corner. Oh well... time to have the fuel system looked at or getting the fuel pump upgraded. FARK!!!

BTW fuel starvation problem showed up with just 3/4 fuel in the gauge.

:mad:

Hmmmmmm--- the more I read the more I think one could really get involved in a fuel delivery system.
Mazsports system is a really good system but I just dont have that amount laying around here at Christmas. And since I dont have FI that volumne of delivery and 1:1 regulator is not really required. It would be a bit overkill for me but for the FI guys its a great setup.
One thing about converting to a return type system is the likelyhood of throwing emissions based CEL's and I really don't want that but I may not have a choice if just a new pump doesnt solve the problem. By the way I won a new pump for $65 on e bay--gotta love it!
I have a freind working on a set up for me. We will see what turns out.
What I would like to have is like Dannobre's system with just a few more features.
that is a dual pump system--nonreturn---with impact/turnover safety features and a high speed only option(for track use only). The safety features may be available by taping into the stock fump pump wiring harness and upping the 15 amp fuse to a 20 or 25. I dont know for sure that is why I am letting an expert think about it.
WHo knows---if we can get a practical low cost kit available--maybe we can even market it?
olddragger

Hmmmmmm--- the more I read the more I think one could really get involved in a fuel delivery system.
Mazsports system is a really good system but I just dont have that amount laying around here at Christmas. And since I dont have FI that volumne of delivery and 1:1 regulator is not really required. It would be a bit overkill for me but for the FI guys its a great setup.
One thing about converting to a return type system is the likelyhood of throwing emissions based CEL's and I really don't want that but I may not have a choice if just a new pump doesnt solve the problem. By the way I won a new pump for $65 on e bay--gotta love it!
I have a freind working on a set up for me. We will see what turns out.
What I would like to have is like Dannobre's system with just a few more features.
that is a dual pump system--nonreturn---with impact/turnover safety features and a high speed only option(for track use only). The safety features may be available by taping into the stock fump pump wiring harness and upping the 15 amp fuse to a 20 or 25. I dont know for sure that is why I am letting an expert think about it.
WHo knows---if we can get a practical low cost kit available--maybe we can even market it?
olddragger

that is so funny.. i almost sent you a pm about that fuel pump.. wish i had now... i was going to buy it and offer it to you to experiment with.... ended up bidding it up more, but not very much...


beers :beer:

Mazports system isn't any more a return system than stock...from what I can see?? the stock system regulator dumps into the same position in the unit as the regulator in the upgrade. It has too to run the venturi. Thje big difference is the capacity of the pump...and the rising rate regulator when the car is in boost.

FYI OD..both pumps run on the stock wiring harness on mine...with the same fuse......never blown on me yet. both pumps will run at low speed...until the ECU says....go fast :D:

WHo knows---if we can get a practical low cost kit available--maybe we can even market it?
olddragger
I'd get one ASAP. Please do a kit with an easy to do DIY.

By returnless it is meant that no return line from the fuel rail to the tank exists.
Swoope------agggghhhhhhh! Cost me 10bucks! He was a good e bayer--it was at my home 3 days after paypaling.
Dannobre-- I think that Mazsports system is much more of a return system than the oems--because Scott said his system coverts it over to a return line system. See his post.
Like that system you have.
olddragger

Dannobre-- I think that Mazsports system is much more of a return system than the oems--because Scott said his system coverts it over to a return line system. See his post.
Like that system you have.
olddraggerNo return line on either that I could see :D: Would need upgraded fuel rails to do a true returnless system

or the last several months we have been testing and are now proud to release our fuel system upgrade for the RX-8. The stock fuel pump appears adequate for moderate performance increases we have witnessed failures such as locked up and dragging pumps which have led to internal engine damage.
In a rotary equipped vehicle, reliable, consistant fuel pressure and flow are extremly important and this system was designed to support 400+ rwhp using tried and true components from years of our RX-7 development. We have incorperated a rising rate fuel pressure regulator and have converted the system over to function as return line system which also has eliminated some fuel slosh issues. The factory fuel pump carrier assembly is removed, ours is installed as a unit then the factory fuel line and electrical connections are reattached making this a truly plug and play system. For more information check it out on our website Mazsport.net
__________________

Dannobre this is the post by Scott concerning his system and him saying he converted it over to a return type. You dont have to change the fuel rails to do this.
OD

that's intended for higher HP applications where adequate fuel flow is required, not for lateral load suction issues

true--read my earier post.
OD

Well my gage showed half way between 1/4 and 1/2.

It was the last lap before cool down.

After running out of fuel I went to the pit.

After ten minutes the gage dropped to 1/8th.

On the fastest track in the West my fuel starvation problem was at 1/8th of a tank.

I talked with Kelly, and she said she ran out of fuel twice at around 1/4 tank.

That's the lastest feed back we have on this issue.

http://www.rx8club.com/showthread.php?t=136459

Well my gage showed half way between 1/4 and 1/2.

It was the last lap before cool down.

After running out of fuel I went to the pit.

After ten minutes the gage dropped to 1/8th.

On the fastest track in the West my fuel starvation problem was at 1/8th of a tank.

I talked with Kelly, and she said she ran out of fuel twice at around 1/4 tank.

That's the lastest feed back we have on this issue.

http://www.rx8club.com/showthread.php?t=136459

you still with the original pump?????



beers :beer:

Yes, we both have the orginal pump.

I'm just surprised the gage was so off.

Now that I think of it.. scientifically speaking the centrifigal force kept the gage up so it couldn't drop and show the accurate reading.

The track is a momentum track where you really don't have to use your brakes except two or three times. (if your good or brave)

A spec mita got a 1:36 on the 2.5 mile course.

Man must have been one hell of a roller coaster ride. Full speed all the way around Yee Haw!

Yes, we both have the orginal pump.

I'm just surprised the gage was so off.

Now that I think of it.. scientifically speaking the centrifigal force kept the gage up so it couldn't drop and show the accurate reading.

The track is a momentum track where you really don't have to use your brakes except two or three times. (if your good or brave)

A spec mita got a 1:36 on the 2.5 mile course.

Man must have been one hell of a roller coaster ride. Full speed all the way around Yee Haw!

the pump is on its 5th version.. i dont know of anyone that has reported on how it does on the track.

but for the price it is cheap insurance... 135 bucks.

beers :beer: