[F419sr1]

I had a twin fore installed on my 17 Zl1. Took it to the track. Ran fine during the first 20 min session. Burned a 1/4 tank. Second season about two laps in on right turns it started shutting down or pulling power. Topped the tank off and runs fine. Anyone else have a problem with it sucking air. I tried calling fore but they won’t talk to you. Everything has to be done through email which I think is ridiculous. For as expensive as the system is and they can’t even take the time to talk to you.

[SFV1LE]

Sounds like fuel starvation. Is this ever a problem with untuned ZL1s with stock pumps below 1/2 tank in high G turns? Never heard of this on ZL1.

Evo X has this problem below 1/2 in high G left turns--requires a fuel surge tank.

If you get fuel starvation at WOT it can damage your motor--stop tracking it and replace that pump with a proven reliable solution.

[F419sr1]

Originally Posted by SFV1LE

Sounds like fuel starvation. Is this ever a problem with untuned ZL1s with stock pumps below 1/2 tank in high G turns? Never heard of this on ZL1.

Evo X has this problem below 1/2 in high G left turns--requires a fuel surge tank.

If you get fuel starvation at WOT it can damage your motor--stop tracking it and replace that pump with a proven reliable solution.

I didn’t have this problem with the stock pump. It would suck if it has to come out. Huge waste of money. I put this pump in so I wouldn’t have this problem. The stock pump was borderline on the edge of its capacity.

[SFV1LE]

Originally Posted by F419sr1

I didn’t have this problem with the stock pump. It would suck if it has to come out. Huge waste of money. I put this pump in so I wouldn’t have this problem. The stock pump was borderline on the edge of its capacity.

Good luck solving it. I don't know much about ZL1 fuel system mods, but with the limited research I've done I noticed a few things:

• Information is difficult to find, e.g. there is no clear solution for +150 WHP w/E85 that everyone agrees on.
• Some solutions like voltage boosters seem unreliable--not something I'd trust in my car on track with a tuned high HP motor and no warranty.
• The better solutions are very expensive--XDI injectors alone are $2,500+, and you need a lot more to support those.

[F419sr1]

Originally Posted by SFV1LE

Good luck solving it. I don't know much about ZL1 fuel system mods, but with the limited research I've done I noticed a few things:

• Information is difficult to find, e.g. there is no clear solution for +150 WHP w/E85 that everyone agrees on.
• Some solutions like voltage boosters seem unreliable--not something I'd trust in my car on track with a tuned high HP motor and no warranty.
• The better solutions are very expensive--XDI injectors alone are $2,500+, and you need a lot more to support those.

From what I was told fore was the way to go. In tank replacement and the twin pumps can support well over 1000 wheel. I’m at 800 on 93. Pump is fine in a straight line. Just can’t turn right.

[travislambert]

I know exactly what's going on because I experienced something very similar recently.

With a saddle tank, anytime you have less than a 1/2 tank of gas and take a hard right turn, every drop of gas migrates to the leftside tank (I have data logs from the fuel level sensors from each side of the tank.). From there, your fuel pump is only pulling from one jet pump. Even the stock pump with a stock engine is far less efficient in this state, but it still has enough capacity to work (barely).

These aftermarket guys like DSX Tuning and Fore Innovations only think about drag racing, and they pack all of their eggs in the rightside tank basket (so to speak). For roadcourse and even aggressive righthand turns on the street, that simply doesn't work because you have to have enough fuel supply capacity while operating from either tank exclusively in order to avoid fuel starvation. I'm shocked that we don't see more blown engines due to this problem causing engines to run lean.

Fore innovations also deletes the bucket from the pump which only makes this problem worse. Normally, the bucket will serve as a buffer while fuel is sloshing around. Without this you will have intermittent fuel pressure drops when you're below 1/2 tank of fuel. I'm not sure you'll fix that without a surge tank or something.

I feel for you. My solution was to go back to a stock pump with the JMS voltage booster running at 17.5 volts. I validated this at VIR a couple of weeks ago which has the perfect test layout for this problem. It has a HARD right turn with a long uphill straight. At the end of the straight, my car is running at about 160MPH without going lean with only fuel in the leftside tank.

Unfortunately, at your power level, you'll need a different solution. At 700 RWHP (on 93), I'm at the very limit. I was still starving the car for fuel at 17.1 volts. At 17.5 it barely holds pressure. I'm not certain, but I think you have to jump through some hoops to get the voltage any higher than 17.5 without having issues.

[SFV1LE]

An external trunk mounted surge tank would definitely solve any tank pickup starvation issues and would eliminate the need for modified pump setup in tank. The stock lift pump could supply plenty of fuel to keep an external surge tank full, and the surge tank gets the high flow pump(s) to support high HP. Get a decent sized surge tank so it can last through long turns like NASCAR oval banking. Radium and Nuke make some very nice ones, but they're expensive. The best solution is a fuel cell with a built in surge tank. Here's an example: http://www.radiumauto.com/FCST-Fuel-...ank-P1497.aspx

[GunMetalGrey]

I had this issue for 2 years off and on and I think it is fixed now... GM replaced the fuel pump 3 times (which caused the problem to go away for a little every time before it came back) then they realized they should replace the scavenger pump which sits on the left side of the saddle/W shaped tank and pumps fuel back to the right side where the main fuel pump is located.

However I've only attended 2 events this year so far with this new fix.

When they had replaced the main fuel pump in the past, it fixed the problem for 3 months of tracking before it showed up again at the last event of the season in September.

[GunMetalGrey]

Originally Posted by travislambert

I know exactly what's going on because I experienced something very similar recently.

With a saddle tank, anytime you have less than a 1/2 tank of gas and take a hard right turn, every drop of gas migrates to the leftside tank (I have data logs from the fuel level sensors from each side of the tank.). From there, your fuel pump is only pulling from one jet pump. Even the stock pump with a stock engine is far less efficient in this state, but it still has enough capacity to work (barely).

These aftermarket guys like DSX Tuning and Fore Innovations only think about drag racing, and they pack all of their eggs in the rightside tank basket (so to speak). For roadcourse and even aggressive righthand turns on the street, that simply doesn't work because you have to have enough fuel supply capacity while operating from either tank exclusively in order to avoid fuel starvation. I'm shocked that we don't see more blown engines due to this problem causing engines to run lean.

I feel for you. My solution was to go back to a stock pump with the JMS voltage booster running at 17.5 volts. I validated this at VIR a couple of weeks ago which has the perfect test layout for this problem. It has a HARD right turn with a long uphill straight. At the end of the straight, my car is running at about 160MPH without going lean with only fuel in the leftside tank.

For me the problem started at 1/2 tank or less but then it started doing it around 2/3's as well. My ZL1 is stock.

If the replacement of the scavenger pump on the left hand side of the tank does not solve the issue, I'll try what you've suggested.

So far it has solved it, but replacing the main fuel pump 3 times also solved the problem each time for a few months .

[Juiced1]

Fore pumps are two big for a fuel bucket. So you really need to keep it above a quarter tank. Without a fuel bucket when the fuel sloshes to one side of the tank you can run dry. Fuel buckets keep a small reservoir around your pumps and without them you have to be careful.

[LiqTenExp]

With cam you can easily take stock fuel pump + JMS Fuel Max in to the low 800whp range (load dyno #s) on 93. I'm in the low/mid 700's w/o issue. I'm set ~ 17.4 V.

I was looking to go Fore and now I'm glad I didn't. I had not put the effort into evaluating the fuel bucket and fuel tank saddle into the picture. Thanks for the details guys.

Originally Posted by travislambert

Unfortunately, at your power level, you'll need a different solution. At 700 RWHP (on 93), I'm at the very limit. I was still starving the car for fuel at 17.1 volts. At 17.5 it barely holds pressure. I'm not certain, but I think you have to jump through some hoops to get the voltage any higher than 17.5 without having issues.

[F419sr1]

Originally Posted by Juiced1

Fore pumps are two big for a fuel bucket. So you really need to keep it above a quarter tank. Without a fuel bucket when the fuel sloshes to one side of the tank you can run dry. Fuel buckets keep a small reservoir around your pumps and without them you have to be careful.

This is happening at 3/4 of the tank

[LiqTenExp]

Sounds like you may want to replace stock fuel pump, add surge tank and place Fore pumps in surge tank if it was happening at 3/4 tank.

[F419sr1]

Originally Posted by LiqTenExp

With cam you can easily take stock fuel pump + JMS Fuel Max in to the low 800whp range (load dyno #s) on 93. I'm in the low/mid 700's w/o issue. I'm set ~ 17.4 V.

I was looking to go Fore and now I'm glad I didn't. I had not put the effort into evaluating the fuel bucket and fuel tank saddle into the picture. Thanks for the details guys.

On the dyno on 93 stock low side it did 803. On the street the pump wouldn’t keep up.