Fuel Starvation Problems
 

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

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/vel...urge_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.
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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

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

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 :(