Jason89RS

iTrader: (2)

I'm helping my buddy with his badly running Iroc. The car is a completely stock 86 Iroc with 305 TPI and has a new AC Delco fuel pump and brand new fuel filter. When the car is cold it runs good and has quite a bit of power. Once the car warms up it idles fine but when you get on the throttle it sputters and starts cutting out and falls flat on it's face. It doesn't matter if you just floor it or roll into the throttle the result is the same. It doesn't feel like a miss, more like not enough fuel so we hooked up a fuel pressure gauge. At idle and when reving the engine in neutral the fuel pressure stays good. We then taped the fuel pressure gauge to the windshield and found that when the car starts cutting out when driving the fuel pressure starts fluctuating wildly and then drops to about 15 psi. It seems to me that something is telling the computer to shut down the fuel pump. During the testing the computer threw a code 43 so we replaced the ESC module, but problem still persisted with the new module.

Anybody had this same issue and if so what was the resolution?

rock861261

sound like a bad fuel pump or a bad regulator... should be something like 40 psi

Jason89RS

iTrader: (2)

We don't think it's a fuel issue since when the motor is in open loop it runs pretty good and has power, but when it warms up and goes into close loop that's when it starts having issues.

1tpi

When the motor warms up it goes into closed loop

Jason89RS

iTrader: (2)

Thanks I always get them turned around.

1tpi

Your fuel pressure should NEVER go to 15 psi it should
be in the 40's

thegooseman

Have you checked the injectors? Do an ohm test on them cold and warm. I honestly dont know off the top of my head on the the ohms should be, but the info is on here. I remember Don telling me about a couple cars he was working with. If I remember correctly the cars had similiar issues as your buddy. On both cars at least one injector was bad.

Jeffs82TA

iTrader: (1)

43 can be the magnetic pickup coil as well

1tpi

Did you fix your fuel pressure
problem, with it going down to 15 psi, no way
should it do that

Jason89RS

iTrader: (2)

Wow has it been a year since I first posted this.....I thought I'd give an update if anyone cares. First I now own the IROC with the issues above. Second after testing and trying different things trying to avoid dropping the tank, I finally broke down and pulled the tank. I first had to drain the tank, which was about half full, so I disconnected the line at the back of the car and used the pump to drain it. It took about 8 - 10 min to pump out 2.5 gal.....definitely something wrong there. After dropping the tank and opening it up I found that what I had been told was true when I acquired the car....that it had a new sending unit and fuel pump installed about a year ago. What else I found was that the tank was full of rust and the fuel pickup sock was clogged with rust. The idiot that owned it before me installed a brand new pump and sending unit into a very rusty fuel tank that had been sitting for a couple years. So now I'm in search of a used fuel tank, which should fix that problem.