Series 1 Fuel Pump on Track- What Was Your Solution?
 

Hi All,

As the title states, I'm curious as to what others are doing on the track about their poor quality s1 fuel pump?

While I've read a bunch of threads/ posts about the series 2 install or Walbro/ DeatschWerks pumps, I've heard no real follow up to the effectiveness/ longevity of the s2 install; and from what I've gathered, most people are unhappy with their Walbro's.

Thanks in advance!

The Aeromotive is an easy install.....I think the pump is good quality and has more capacity than the S2 pump...

The basic fact is...if the car gets below 1/4 tank you will have problems in Left hand sweepers that are long and fast

You options are....second pump in passenger side, altering the fuel tank ( Speedsource )to keep the fuel from sloshing to the passenger side and other mods, or just keeping the tank fuller than 1/4 :)

For most situations the higher capacity pump and keeping the tank fuller is the easiest mod :)

I have 2 pumps, an upgraded siphon and have problems below 1/8 tank...

How about a fuel cell in the trunk, and just ditch the S1 setup? Anybody do that yet?

How about 2 fuel cell's that set where the tank is presently?

Yep..higher center of gravity and expensive :)

Would be nice...but expensive.....damn fuel cells are close to 2K :) Would need crossover plumbing and 2 pumps and a ton of custom fabricating

Yeah, not looking to do a fuel cell. Either the s2 pump or new aftermarket drop-in.

I read about some guys having fuel pressure problems with the aftermarket drop-ins? It this common & would a regulator be in need?

read the first page or two to get an understanding of what you are dealing with before going thread happy here

https://www.rx8club.com/major-horsep...-modes-176491/

Team- Although I may not have been on this particular forum for very long, I'm hardly a noob. Having worked on rotaries for 15+ years now at Mazda dealerships & rotary specialty shops in CA, in addition to owning all Rx7 gen.s & vintage rotary.

Now, I've seen the thread & found it inconclusive with no definitive result as to the performance/ longevity of the install. I wanted real experiences from the people out there on the track. Not just a write up of what illustrates the specs & function of the original OE unit which I'm trying to replace. :)

I had the problem, replaced it with a cheap, Advance Auto Parts unit (unit failed AT the track) and was out turning left at high speeds with 1/4 tank of gas. I will likely play with an upgraded pump when this one fails now that I have an extra assembly...

The stock setup seems to work until it wears out. Mine lasted 100,000 miles.

That help?

Federighi - Be careful what solution you choose. If you plan to do any type of race event: Wheel to Wheel or Time Trialing - Your solution can dramatically affect your classing and hence your competitiveness.

You may only want to do track days now, but then choose to move on, as many do. Changing the fuel pump may affect your classification. Read the rules carefully.

I use a set of Walbro pumps, one in place of the OEM pump and another in a transfer setup. Currently we can suck out all but about 16oz of fuel from the tank.

any updates on reliabilty of 2 pumps?

No reliability problems......

Be aware a non-Base Trim Model fuel pump is a +2 points Mod for NASA

Is anyone running the aeromotive pump in the series I ? If so have you experienced any issues aside from the fuel starvation under a 1/4 tank? Anyone seen heard or experienced damage to the pressure regulator or any other part of their fuel system?

No issues for me.....I don't run the stock FPR though so I can't tell you about that....can't see it being a problem. The siphon assembly needs to be modified thou so it doesn't blow it's top :)

^aware of the siphon, my big worries are with the regulator or any other issues with running a higher flowing pump. And how it performs as a daily driver as well.

On an NA engine it will be continuously recirculating fuel to the point of excess. Ideally a voltage controller to slow it down would be advisable.

Yes I did Run it...


Pump failed after 1 weekend of racing. Possibly due to a vapor lock issue that we had (my fault as I left tape over the vent on the quick fill system we installed) or poor cooling when the fuel level got low? Honestly not really sure and didn't replace it. I concluded after tI had it that the fuel was also getting hot for no reason. Basically it pumps WAY more volume than you need so the gas just keeps recurculating as TeamRX8 mentioned. Each time it goes through the pump then back into the tank through the regulator it heats up more and more for no reason. Hotter the fuel equals less HP.

I am running a series 2 pump now which DID require some electrical work and changes to the vent hose fitting. On the other side we are running a LOW pressure pump to use only when the fuel gets low. This way we are again not just recirculating fuel and heating it up for no reason.

This weekend we are running a 4hr event at the glen with the car. I will let you know how it goes in this thread if you would like.

Stephen

On Edit... the aeromotive pump is also slightly taller and I didn't really like how tight it made all the flexible lines attached to the regulator and pump assembly after it was compressed in the tank.

Great read thanks for the info/ feedback

This past weekend I ran the Series 2 pump as described above in a 4 hr long race. This race requires 2 mandatory 5 minute pit stops as most cars can make 4 hrs with 2 pit stops and SCCA keeps safety first. So they have us stop for 5 minutes which should allow plenty of time to fill up without rushing and spilling fuel everywhere.
(We however needed to fill-up twice and then stop for another 6 gallons at the end:banghead:)

In the First stint I found out that the car still sputtered after about 45 minutes of racing. At that point however I turned on the second low volume pump that is mounted on the passenger side of the car. It ran for another 26 minutes after that until we had a full course yellow and we made a pit stop as we knew we would run out soon. This first stint had about 15 minutes of yellow flag time mixed in and we estimate the green flag conditions were about 56minutes. (Remember under yellow we do everything we can to use as little fuel as possible) During this stop we put in 75lbs of gas (about 13.8gal)

The second stint we ran for 1hr and 8 minutes and again had a full course yellow at the perfect time and we new we had to pit and take advantage of the Full course yellow to fill up. This stint also had several cautions and we estimate we ran under green for 54minutes. We did run the second pump at 1/2 tank and did not wait for a sputter this time. This stop the car took in about 73lbs (about 13.5 gal)

The third stint the car ran for 1hr10 minutes with only about 5 minutes of yellow so we ran about 65minutes under green flag. HOWEVER in this stint we were close to being able to finish the race! Remember this race required that we make 2 mandatory 5 minute pits stops so if we could get the car to last 1hr 30 minutes we wouldn't need to stop! Sadly though at that 1hr 10min mark the car sputtered on a left hander and then died completly! Luckely I was close to pit lane and able to coast into pit lane where it did start again about 1/2 way down pit lane. To me this was a clear indication the car was pretty much completly empty. We estimated with quick math that 6 gallons would safely get us to the end so we added that and continued the last 18minutes.

So in the end I would conclude that the car uses just over 1.3lb per minute under green flag conditions. A gallon of fuel is about 6lbs so that is a gallon every 4.5 minutes! :SHOCKED:

Anyway how does this all relate to this thread...
I think the Series 2 pump works fine BUT you still need to add that other low volume pump if you want to get everything out of the tank. Anything less than 1/4 tank you could easily get fuel starvation IMHO. Just by design I don't see it any other way on a high G or long enough turn.

I also had 1 other major observation which was that the gas guage did not read accurate for us for some reason. when we pitted each time we still showed just under 1/4 tank with no yellow light on. Each time we put in over 13 gallons of gas which is almost empty. We are running the stock guage with stock senders. I am wondering if this has something to do with fuel slosh or the series 2 pump reading differently. Afterall the series 2 tank is deeper than the series 1... just something to think about, we don't have the answer.

Stephen

There are some provisions for a transfer/lift pump and such. The pump that feeds the engine is the one you need to watch.

Stephen - I've gotten better results with my wtw MR2 doing my fuel volume / weight calculations at 6.25lbs/gallon. If anyone has an even closer figure than that I'd love to hear it :)

- KB, fuel starve victim as well, the R3 on street tires doesn't like being below 3/8ths (ie a couple marks above 1/4th).

It is difficult to know exactly because it changes with temperature. It also changes depending on additives and such. I know in the aviation industry they use 6lbs which is a slight variation from automotive fuel. For us we measured 8 gallons which came out to 48.5lbs of gas. when measured with our bathroom scale and 48lbs when measured with the car scales. Lots of variables here that do not make it exact. For example the pump at the station that we used (Was ait exactly 8gal?), and the scales that we used. (The bathroom scale measured to the tenth but that certainly wasn't taken to a calibration company, then the scales we used at the track on pit wall only do lbs no tenths...) so for us we measured the fuel we actually had and came up with just under 6.1lbs per gallon for the fuel we had been using that day. We kept the 6lbs calculation since the varience was less than 1lb AKA less than 1/6th of a gallon difference.

I would argue that for us we wanted it full so we packed it until it was full no matter what. The measurements that we had above are from measuring the can before gas went in, then with what was left over then subtracting the weight of the can itself. The only reason we did mesure was to try and figure out how long we thought we could go if we ever do this again and to make a pit strategy work for the best with full course yellows. The other big variable is the amount of caution laps, how fast those caustion laps were ect. Lots of variables to consider. But we do know that if we do a 4hr event again we know at or around 40minutes if we get a FCY we need to top it off...

If running in a sprint race 1lb or 2lbs max will hopefully not make a difference at the end of the race on the scales. we shoot for 5lbs-10lbs over to be safe.

Stephen