MzSin

First off, I've been lurking for months, and thank you to everyone. Your posts have been so helpful. Everytime I Google my question, this is where I end up. But I am at my wits end, so before I drop a tree on my car, any suggestions?

I have a 1991 Firebird with the 3.1 engine. Purchased in February of this year, engine was an original rebuilt with 55000 miles. New tranny. Guy was rebuilding it, starting with the mechanical and had to sell. He was driving it daily and it was from a friend of a friend and was checked over by two mechanics before I picked it up for next to nothing. Needs paint! They said. You're such a lucky girl!!

It made the trip from WV to Toledo twice since purchase, then on the third attempt, it failed me. About an hour south of Lima it started to miss a bit, getting progressively worse until the rest stop after the Neil Armstrong Museum it backfired and died, along me to coast up the hill into the rest stop but refusing to start back. I spent two days at the garage but they couldn't figure out what was wrong with it. I had a friend with a truck and a tow dolly come drag us home.

It throws NO codes, save 12. Since June, we have replaced the Ignition Module (twice), MAP sensor, Fuel pump, Fuel Relay, Distributor (Entire assembly), plugs, wires, Fuel Pressure Regulator, ECM, starter and alternator. Numerous other parts I am probably forgetting. It gets fuel pressure. It gets spark. And today WOOT!! It ran!!!! For about 5 minutes. Sounded to me like it was running a little fast, but its been three months since I last heard it and I don't know. Took it up the block and it was fine. Took it down the block and turned at the bottom of the hill and it started to miss. Before I got turned around, it sputtered and died. It will idle really rough for a few minutes, then slack and die.

I need new ideas. Or C4. Any help is appreciated. Just keep in mind I am a single mom on a serious budget, so I don't have a lot to work with. Thank you!!

MzSin

It finally decided to be cooperative. With the paperclip method, it gave me a code 33. Already changed the MAP. Tomorrow morning, we start tracing hoses.

BahN

High idle is very characteristic of a vacuum leak. Low VAC (code 33) could also be effecting your fuel pressure, essentially fouling your plugs. Check the obvious, brake booster, line to the fuel pressure regulator, and timing. Another possibility is a sticky EGR, although I would suspect it throwing other codes besides just 33.

MzSin

Thank you!!

Atilla the Fun

The first post seemed to be a failing alternator. But after reading the rest, I'm not so sure.

red rock

iTrader: (2)

I don't know anything about the 3.1, but i would also check the wiring from the ecm to the map along with any vacum leaks. Sounds like a wire is going partialy open on one side. Also check all your grounds for good contact. Good luck!

MzSin

Update: It is sitting in the carport now, running fine for the moment. I don't know if the previous fuel relay was bad or if something caused it to blow but when we started it today, I didn't hear the pump kick on. We replaced the relay and its is running. Going to take it for a test run shortly. Wish me luck, and thank you for the suggestions!

MzSin

Grrrrrrrrrrrrrrrr!!

Back to square one. Cranks and tries to start but won't catch.

Code 33 and Code 44. Bad wiring? Fuel injectors? How do I test these things?

red rock

iTrader: (2)

The first thing to do if you haven't already is to go to a local parts store and buy a Haynes or chiltons repair manual. They will have some good info on wiring and vacuum lines. Some times these problems can be expensive if you keep throwing parts in without checking the basics first. Code 44 is lean exhaust, code 33 is map, sounds like a vacuum or gasket leak.

MzSin

Haynes Manual was the first thing I bought. Garage changed the ignition sensor (twice). Everything else was a progression of it acting like it wasn't getting gas. Have now checked every vacuum line and every wire we can find.
New idea suggested: Oil sensor (I've worked 16 straight 9 hour shifts, will list the exact part if it works). Apparently if it goes bad, it tells the computer that the engine is low on oil and it will not turn over. Tomorrow will tell.

Vader

Test the resistance of EACH fuel injector (unplugged from the harness) when cold. If one is below 10 ohms, do not reconnect it. If the engien starts and runs, allow it to run for about five minutes to warm up the injector solenoids fully, then test the resistance of EACH injector again. If any are below 10 ohms, replace them.

The Multec injectors are notorious for causing this kind of problem.

If the injectors test between 12-16 ohms both hot and cold, they should be good. Report back.

Vader

That is a common misconception. The oil pressure sensor has nothing to do with allowing the engine to crank, does not affect ignition, and does not affect injectors. It is a parallel power path for the fuel pump power in case the FP relay fails. This is NOT a Ford. The pump runs regardless of oil.