smiley23

I have been messing with this for a while now - so now I ask the experts. Sorry about the length of the post.

My conclusions so far lead me to think it is fuel delivery or vapourizing fuel. I am hoping one of you have run into this problem before.

Car runs great in the mornings (88 IROC 5.7TPI) - on the highway 70-80 mph and still power to pass.

In the afternoon (home from work) it is hotter (it began as the warmer weather approched), get the car up to 70mph for about 10 miles down the highway and you can just barely feel the power fall off. I can hold it at 70 the whole trip.

- If I punch it to pass - it falls on its face (stalling) and back fires a few times. (through the intake)
- Put it into nuetral and punch it - same result.
- After getting off the highway and running the city streets for about 5-10 minutes. I am able to punch it again without it falling on its face (stalling) over 2500RPM

Things I have done:
Replaced the fuel filter
replaced the cap and rotor (both were worn excessively)
Loosened off the gas cap to eliminate back pressure.
Soon to send the injectors out for proper cleaning.
The CAT has been hollowed out - so it cant be plugged.

Dont want to change the fuel pump unless I have to. I am guessing that is the problem or is it the fuel pressure regulator? I have yet to find a fuel pressure gauge that I can hook up and drive this trip to monitor the presure before the regualtor.

Oh - and of course - there are no codes generated!!!

Oh - BTW - this car is hard to start too. You need to use the gas pedal to start it. That is why I plan to clean the injectors and change the plugs in one shot.

fisherbody86

Don't overlook the ignition module, heat soaked module failure is a very common problem with GM modules. Do yourself a favor, STAY AWAY FROM NAPA MODULES!!! If I were you, I would order up a new accel module from jegs for like $45, because even if it doesn't solve the problem it is a way better unit that the factory one.

smiley23

Good point - I sould check that one out too.

smiley23

fisherbody86 - you rule !!!

You put me in the right direction anyway. I bought a new Ignition module the other day and when I went to put it in - I found that the connector from the stator to the module was gone (no plastic shield). There were 2 wires just barely attached to the ignition module.

I figured since I got it appart - I might as well replace the module anyway - even though it did not look like that was the problem.

No more stumbling or "falling on its face" when power throttling it on the highway.

THANKS !!!!

IrocZonNos

I suffer from the same problem... Where and what is the ignition module used for?

smiley23

The ignition module controls when a spark is transfered from the coil to each castle on the rotor.
ie. when the rotor turns inside the rotor and it passes a castle (where the spark plug wire connects at the distributor) the spark signal is sent to the coil to charge/energize.

The location is at the base of the distributor - pull off the distributor cap and you will see 2 connectors plugged into the black (usually) ignition module - careful when you remove it since there are 2 more wires on the other side of the modules that are plugged into the stator (or pickup sensor).