95 TA Loading Up
 

Happy Thanksgiving to all.

My 95 TA is acting up and is very frustrating to find the problem.

Symptoms-car will run fine for quite a while after reaching normal running temp. Will run fine 20-30 minutes. After this period of time it starts to bump a little at idle. Put it in nuetral rev it up to clear it and it will be fine. Continue on for a little longer and all of a sudden without warning at idle, it will go full fuel, load up, backfire out the intake, and eventually die. Acts like a carb motor with a stuck float. It will restart and you can clear it out, but it will happen with continouing frequency. Let the car sit 3-4 hours and the process starts over.

I have 28 years experience working on classic Pontiacs and own a Pontiac specific shop. I understand mechanical and electrical systems very well, but until obtaining this car for myself have no previous experience on the LT1. I have limited computer controlled experience on anything later than 1986.

Before obtaining the car, it sat for about 2 years. I did all the obvious, drained tank, new fuel pump, new fuel filter, fluids, hoses, belts.

Fans did not work so there is a new temperature switch installed.

The car ran fine for approx 200 miles.

There are no codes, no history, and no check engine light. Alternator is charging properly. Went through all the ground connections and cleaned-retightened.

I went for the obvious, MAP, MAF, O2 sensors. Checked EGR for proper operation.
MAP was completely plugged shut and thought that was the problem. Replaced, but did not fix. Replaced O2's, MAF because of 133,000 miles

Previous owner says plugs, wires, and opti changed about 12,000 miles ago.

Anyone had this proble? Know what it is?

Thanks

have you put a fuel pressure gauge on it and observed while it acts up?
My guess is FPR or the pump

Curious what this turned out to be?

+1

My guess would be either fuel pressure regulator related (reg itself or the vacuum that operates it)

the pressure at teh test port should be ~41-47 psi without the vacuum on it.

I know this is a old post but it cuda been the vac diaphram in the psi regulator. They pinhole sometimes and send raw fuel into the intake thru the vac line..