I have an issue where the FD starts and runs fine until the fuel pump seems to heat up. Then it acts as though it is getting no gas, cuts out, or chokes and backfires until it finally cuts out. Pull over for ten minutes and it restarts fine until it heats back up and does the same thing. I have a pfc, Vmount, fpr, reliability mods. I replaced the fuel pump and same issue, so it doesn’t seem to be the pump. But it does seem to occur once the pump gets hot. Staying under 4k rpm’s and happened after about 20 min of driving.
Any ideas, I’m at a loss.

 

Are you still using the o ringed fitting at the pump feed on the hanger?

 

No, hose fitted directly to the pump.

 

Next time it does it make note of your water and air temp and afr. Once it cuts out, spray some starting fluid in the uim and see if it fires up right away.

Presumably your power fc is tuned and it's not a situation of it hitting a certain temp and simply requiring a fuel correction..... but lets see

When was the last time you saw the fuel pump and the hose thats attached to it? If you used the supplied hose with the pump or any non submersible fuel hose, I can 99% guarantee the hose is split.

 

actually, it is not tuned per se’. I am/was on break in miles, new motor. It’s got my turbos off, so I don’t go above 4000rpm currently.
took it to get tuned, but it started blowing white smoke under boost, bad turbo. Waiting to get a single in to replace the twins. Driving untuned with no turbos active currently. Not much fun, but, I get to drive it.

 

I was wondering if there was a setting/cut off in the pfc that may be causing the problem

 

Likely... from what it sounds like, it's going to be an air temp correction but I'll need you to verify. Next time it does it, make note of the air temp. Then you'll wait for it to cool down, start it, make note of the air temp again and then watch it until it does it again. It will cross over into the range where it likely just needs a bump in fuel compensation

 

What PFC map are you using? In addition to the hose do you have a voltmeter to see what power is going to the pump?

 

I saw the hose 2 days ago, it’s fine. The map, done by the shop so I am not sure. And I do have a voltmeter. The power seems fine, it runs fine, all the way up until it heats up

 

if FD Auto's suggestion doesn't pan out, borrow/rent/buy a fuel pressure gauge and see if its the fuel system.

 

I have an FPR on there already.

 

but what is the fuel pressure? does the pressure do something weird when the car acts up?

 

This sounds like bad tuning / incorrect map on the PFC

 

mine does this actually. when its cold its good, and when its hot its good, but when its warm it idles bad.
i think my air temp map needs a tweak. i did a couple of logs, but forgot to unplug the air pump, so i get to do it again, lol

 

that’s also a pretty common “fuel pump on it’s last leg and about to fail completely” scenario as well.

yet as requested, the pressure log should tell the tale …
.

 

Has your fuel filter been changed?

 

the fuel pump is brand new. This occurred with the old
Pump, so I replaced it and same issue. However with the smaller pump it didn’t happen as quickly. I am assuming the bigger pump, Walboro 450, it’s heating up faster.

 

There is a situation where the TPS will go out of phase when it gets hot. It will otherwise test OK. It may be remote, but how about borrowing someoneelses TPS and see if that helps.

Otherwise running without a turbo seems to be a 900 lb gorilla. If the power fc is "untuned" then it would be running on its base map, would it not?. The base map would assume a certain amount of forced air from the turbo. Would the result be you are running super rich? Meanwhile the PFC may be getting unexpected feedback, outside its expected parameter range, and may just be saying wtf?

 

I sent a PM to the owner. Unfortunately he does not have a datalogit se we can see the map. If its on a break in tune map, there could be a bunch of parameters not setup correct. Assuming by his responses that its setup for twins and he has a single turbo on the way. Ultimately, it will have to get property tuned or he will have to get a datalogit for us to see the map to understand what is going on.

 

Unless I am not understanding things, unless the turbo is actually removed, the front turbo is always "on", is it not?

 

It is... you are correct

 

So, I’ve tried everything, new fuel pump, tps parameters, temp checks when it acts up. Nothing makes sense. The air and water temps are all different each time it starts cutting out or backfiring and then dies while driving.
Read someone had similar issues with bad spark plugs, going to replace those, but, if that doesn’t work, any suggestions on getting a Datalogix? Seems like that could help diagnose current and future issues.

 

I had a episode recently when we could not get the car to deflood. After running through many things, such as you have, we switched out the gas.

The Chevron 94, coming out, smelled - like water -i.e. virtually no gasoline smell.

Shell 93 was put in and fired right away. We did a bit more fiddling and the car started up and has run beautifully.

If you have tried many things, maybe you have to try a different ecu.

 

In post #6 you say this:

"It’s got my turbos off, so I don’t go above 4000rpm currently"

Could you explain more what you mean by that?

Are the turbos still sequential or have they been "paralleled" .

If somehow the turbos "are off", then I would guess the Power FC would have difficulty with readings outside its parameters.

If the turbos are still sequential the front turbo should still be spinning as there is no gate to block the exhaust from the impeller. The gate for the second turbo might not be opening up, and so air flows not coming from the second turbo might confuse the ecu when you get into higher rpm.

If the turbos have been paralleled then front and back turbos should be spinning always and if the boost is not needed the exhaust would be wastegated or the boost blown off.

If I am understanding how things work.

I would still be suspicious of the TPS, and you might want to borrow someone elses' for a whiile.

 

in short, scenario #2. Paralleled and the boost is constantly blowing off. Rather annoying sound too, psshhhhh constantly like a balloon leaking lol.
sadly, I’m in San Diego and FDs are few and far between here to borrow a tps.