Hello,

Sold my car to a friend and now I'm trying to help him figure out what's happening. Car will drive fine around town for about 1.5 hours. Then it starts bogging down. It does not die completely but when you depress the accelerator it does not respond. It will kind of cut in and out but again it does not die completely. Once car cools it will drive fine again. It has only done this twice.

1986 Iroc Z28, 5.7 liter block (out of a 88 burban), TPI, 700r4.
Fuel pump isn't too old, probably about a year.
Just changed the fuel filter but the old one wasn't very dirty at all.
There is definitely gas in the tank.

Check engine light is burnt out so I'm not sure if it is getting codes. Were gonna replace the light and scan for codes tonight but I just wanted to see if anyone could point me in the right direction. I was thinking maybe throttle position sensor or something like that?

Thanks,
Ted

 

Clogged cat?

 

Or maybe ignition module in the distributor.

 

Cat is not clogged, I had actually taken it off because of a rattle a while back and it looked good. I did some searching and everything I read says that when the ignition control module overheats the car dies. But the car does not actually die and have to be re-refired, it just doesn't respond or responds intermittently to throttle. Anyway we'll probably replace the module cause it's only like $30 and see how that goes.

Feel free to chime in with any other suggestions.

Thanks,
Ted

 

Do a search - there's a method to test. Some parts stores will test as well. I never tried, just replaced - wasn't worth the hassle to test to me, they are not that much (under $50).

 

I took one to oreily's and they tested it for free.

 

Even though the pump is new, it would be good to check fuel pressure. youll need to install the gauge so you can read it while driving and run the car til it acts up(intermittents suck to diag). Also, if you could monitor MAF on datastream, that would be great. Other things to think about are IAT sensor, it may be failing at high temp.

Also, injectors are a real problem on these cars. The pattern of your failure could very well be heat soaked injector coils failing. To check for this, you need to watch O2 data and fuel pressure to verify that pressur is normal and that O2 is going lean as it should in this case. Disconnect MAF as problem is occuring to place system in default MEMCAL mode. If problem is still there with MAF unplugged and everything else as it should be, you probably have bad injectors.

 

I had a similar problem, my car would stumble when you accelerate, it was the EGR valve, i replaced the gasket and it solved the problem about 80% so i had to change the valve.. try changing the gasket its only $2 dollars and clean the valve with carb cleaner

 

Is it possible you have some debris clogging the pick up screen in the fuel tank?