jrh2009
New Reader
3/25/21 8:15 p.m.
Ok, so I just had my fuel injected, L98 powered third gen Trans Am out for it's first track day yesterday, and it held up great mechanically except for one thing.
As the fuel tank dipped below half a tank, I could hear the fuel pump start to grown as gas was heating up, and letting the fuel pump get hot. I know I can add cold fuel after every run, but I've also noticed the pump groaning on really hot days or in stop and go traffic.
Third gen F bodies are notorious for killing fuel pumps, so I'm wondering, why shouldn't I stick a cooler in the return line with a dedicated fan?
Not for any performance gain, but to preserve the pump and eliminate the risk of pump failure ending a trackday early.
This is a nice street car so I'd prefer to keep it underneath the car, above the rear axle if possible.
So, is this a stupid idea? If it is, someone talk me out of it please. There must be something wrong with it or more guys would be doing it, right?
I really just don't want to drop the axle again to do ANOTHER pump anytime soon.
Pics for clicks.
Tom1200
SuperDork
3/25/21 8:37 p.m.
So as someone with a dedicated track car with a small fuel cell my advice is just fill the tank up in the middle of the day. That seems like a lot less effort than installing a fuel cooler.
My mentality with any car that sees regular track time is to minimize all potential failure points- especially when it pertains to fuel, as the consequences of failure are pretty extreme. At a minimum you're adding two connections and a mechanical component that could fail.
jrh2009
New Reader
3/25/21 9:15 p.m.
Makes sense, I definitely see your points guys.
I don't mind adding cold fuel after each track session, but I'm still left with the problem of the fuel getting hot on the street.
Im convinced these things go through so many pumps from the fuel cooking. Either from engine heat or maybe the muffler heat, I'm not sure which yet.
I know it happens when the tank is low, or on warm days with stop and go driving. It never did it at the track until it dipped below half a tank.
Just going to throw this out here. How about a Liebig type cooler? Basically surround the fuel line with a bigger pipe and pass coolant through the bigger pipe? Could use a switch to turn it on and off and less connections in the fuel line to fail.
I don't know anything at all about these cars, but it the fuel is getting hot, I bet the exhaust is the main reason. I'd try adding heat shielding around the mufflers before anything else.
FMB42
Reader
3/26/21 5:53 a.m.
You might want to check the fuel tank and fuel line temps with a laser or non-contact thermometer.
What about converting to a corvette type fuel filter and pressure regulator? This would keep the fuel from carrying engine heat back to the tank on the return trip.
You would obviously need to setup the fuel rail differently.
Sounds like another point of failure.
NickD
MegaDork
3/26/21 7:44 a.m.
LanEvo said:
I don't know anything at all about these cars, but it the fuel is getting hot, I bet the exhaust is the main reason. I'd try adding heat shielding around the mufflers before anything else.
If I recall correctly, on a third-gen the gas tank is over the rear axle and the exhaust kicks up over the rear axle as well. I agree, I'd put some sort of heat-reflective shielding on the tank and wrap the exhaust and see what that does.
Eliminate the pump in the tank and put one under the car some place where it can be cool and access is simple for future servicing.
Get a temp probe on the feed and return line to see if its really that much of a contribution. you will need a good amout of delta to ambient where the cooler will be for it to do much.
Being that its a track toy, I am a bit surprised that you havent cut a trapdoor into the the hatch sheetmetal above the tank to make pump replacements easier. It hides under the carpet and you can put it in with rivets, sheetmetal screws or whatever and doesnt have to look like crap if you execute it well.
In reply to NickD :
Third and fourth gen are basically the same from the firewall back, the fuel tank does sit above the rear axle.
The fun part is that it sits in a heat reservoir. Heat from the exhaust, the diff, the air blowing under the car from the radiator, etc. rises up to the fuel tank, and there is nowhere for the heat to further escape to, either above or spilling out to the sides.
Having similar fuel heat issues, I've contemplated things like coolers, and decided that having a big fuel line out where it necessarily has to be exposed, is probably a bad thing safety wise.
That's a sexy looking bird.
I don't really have anything to add. I've replaced my pump twice in 20 years. Neither time was because of failure. Upgrades both times.
Are you tracking in a specified class that would prevent you from swapping to a 4thgen tank? That's what I did. It's plastic, larger capacity, has a fuel pump module that can help baffle fuel in low level situations and the pièce de résistance: the filler neck is removable. So you can drop the tank without dropping the axle. Hell, I don't think you even need to unhook the shocks to get the tank out.
In reply to iansane :
Not all 4th gens had plastic tanks. I know for certain that '95 and '97 had steel tanks, because I modified one of each for dual fuel pump setups.
In truth, I had no idea that ANY 4th gen had a plastic tank. But it's not like you can see it without disassembling half the car.
True, I forgot. Only the LS fourthgens (98-02).
Tom1200
SuperDork
3/26/21 10:28 a.m.
Since the heat has nowhere to go it possible to either add some type of exhaust fan ducting system that pulls the air out the back? Use a computer 4"-6" computer fan and plastic ducting (air cleaner inlet ducts).
slefain
PowerDork
3/26/21 12:40 p.m.
Drag guys used to run cool cans:
Summit stills sells them: https://www.summitracing.com/parts/mrg-1350
jrh2009
New Reader
3/27/21 2:20 a.m.
Really good info guys, I'll start with wrapping and shielding the exhaust immediately.
When I bought the car it came with a new delco pump in the spare parts box, which was nice because the old one started going out as soon as the warm weather hit. So I'm pretty sure heat has killed them before.
I had no idea fourth gen tanks were bigger. But I know more fuel in the system means it would take longer to heat up, so I will definitely swap tanks.
The car is in really nice condition, and is a street car I like to do track days with rather than a track car with a license plate, so I would like to keep everything looking neat.
I appreciate the help. More pics for clicks.
I have a 97 parts car; you could get that tank for next to nothing. But apparently it’d Be steel, and not the later plastic. And I don’t know if Lower Alabam’ is anywhere near you
Header wrap, some sort of heat reflective material on the fuel tank itself or a "cool can" as pictured above on the return line. Maybe some sort of diffuser/diverter above the exhaust before the axle to direct some air up toward the tank.
jrh2009 said:
The car is in really nice condition, and is a street car I like to do track days with rather than a track car with a license plate, so I would like to keep everything looking neat.
I agree that's way too nice to cut up. Probably some of the folks here don't realize how rare a 91/92 GTA is. Nice Trans Am!