1994 Trans Am Stock LT1 with A4 trans.
K&N filter, Cat delete, magnaflow muffler, 185 degree thermostat, high stall converter. Everything else is bone stock.

So here goes... and i am already guessing that the answer is opti... I've never had a problem with my car starting. It has always fired up almost instantaneously on key turn. I came out of work the other day and went to leave for class, and the ignition cylinder was completely locked up, the key wouldn't turn at all. After playing with it for a few minutes, I finally got it to turn. I'm assuming this is a completely unrelated problem, but I wanted to include it just to give all the details.

I drove the car to class non-stop, about 35 miles, mostly highway, with no problems whatsoever. In fact, it seems to have been running stronger lately than it has in a while. I turned the car off and went into class and it downpoured while I was in class. I came out of class and decided that since it was still pouring, I would wait out the storm on campus. About 3 1/2 hours after I turned the car off, I went back to the car and tried leaving. It would not start. It turned over and cranked and cranked and cranked but would not start. Finally, right before i thought the battery was about to die, it fired up and was misfiring and popping and sputtering. I revved it up and after about 30 seconds at 4500 rpm, it cleared up and was running fine. I thought this was odd, so I shut the car off and tried starting it again. again, it cranked for a while before finally sputtering to life. and again, after letting it rev for a short time, it cleared up. I drove it from campus to a restaurant about 10 minutes down the road and shut it off. when i tried starting it again, same story. So from there i drove it home, stopping and putting fresh fuel in it without turning it off, and it made it made the 40 mile trip home with no other problems. Upon getting home and turning it off, it won't start again.

Next morning i go to leave for work, expecting the same problems, and it has rained more over night. the car cranks for about 20 seconds then roars to life running perfectly fine. leave work for class after a ten hour day, and the car starts and is running like crap again, but clears up after about a minute. let the car sit for 2 hours while i'm in class, and it fires right up like nothing is wrong. (dry day) drive it home, let it sit over night, and it fires right up the next morning. leave work for class after another 10 hour day, and it fires right up. (dry day) leave class (still dry) and the car again won't start and runs like crap when it does. same story yesterday. today, its raining a bit, and i go out to look under the hood and notice that the thermostat housing is seeping coolant and its dripping down towards the opti. so i go and buy a new gasket and put it on, careful not to let any more coolant drain down onto the opti, and take it for a test drive, fires right up no problem, running great. make it about five miles down the road and the car just dies on me. stalls while running at about 40 mph. manage to maneuver it into a parking lot and try restarting it, and it cranks and cranks and cranks but will not start. let it sit for about 45 minutes, trying every so often to start it with no success, and finally it fires up running just fine. drive it home with no problems and let it sit outside idling for 20 minutes with no problems. turn it off and try restarting it immediately, and it starts right up, but its misfiring and popping and sputtering worse than it ever has. repeat the process 3 times with the same result.

Other oddities as of late:
Car only runs at about 13 volts once warmed up.
when a/c is turned on, car runs at just under 13 volts.
Currently on start up, during misfire, when you rev the engine, the operating voltage actually drops rather than rising.

Don't know what's relevant and what's not, but i wanted to include everything.


I'm at a loss as to where to start with it. I have people telling me opti, people telling me fuel pump, and people telling me plugs and wires. who here has any ideas? I need to fix it quick, it's still my daily driver for another month or two. Thanks Guys!

 

My guess is opti, but it could be a combination of things. Check for ac volts at pin b at the icm plug when it doesnt start. Thats were i would start. shbox.com

 

Thanks, I'll dig my meter out and check it.

 

my z28 was doing just about the same thing. for me it was a combo of things my fuel pump was getting weak. it was only putting out like 30 psi and that was causing a delayed start. the rubber on the harmonic balance had dry rotted (no it wasn't making any noise) and was spinning on the center piece of it. that was causing low voltage which made it sputter when started for a minute or two until the two pieces of the balance caught up to each other and the volts came up to normal. then when the hot weather started it would make a grinding noise every time i turned the ac on. i assumed it was the ac compressor going bad nope it was the balancer rubbing on the opti which eventually destroyed the opti. are you getting a check engine light if so what are the codes? did you check the fuel pressure?

 

You need to hook up a fuel pressure gauge and start/drive the car. Fuel pressure should stay right around 43psi or so. If it doesn't, then your fuel pump is likely dying.

 

I've got the same deal on my LT1. Sometimes it starts up instantly, other times I have to sit there and crank on it... kinda embarrassing.

 

Embarrassing is having to ask an old lady in a grocery store parking lot to sit in your truck and turn the key as you climb underneath and bang the starter with a tire iron.

 

I have not checked codes recently, but every now and then it throws a light. every time I've checked it it's been an EGR code, don't remember which one. I will check the fuel pressure Friday night. (unfortunately that's the soonest I can get my hands on a gauge that I don't have to pay for.) I can hear the fuel pump kicking on in the back, but that doesn't mean that its sending enough fuel. Thanks for the help guys!

 

been there, done that. but I got lucky and had a pretty cute girl do it. still embarrassing, but not bad eye candy.

 

Getting a fuel pressure gauge from the tool guy today to check pressure. If it is an opti, what brand is recommended for replacement. I can get GM @ 45% off, or a reman one from carquest for $240. Any other recommendations? Thanks guys!

 

if you can afford the ac delco or delphi then go with that. i used one from cardone select because thats what i could afford at the time. its been in there a few months now without any problems. but i always try to use factory oe parts as much as possible.

 

I know exactly how that feels lol

 

I have cranking problems too, always check my FPR and nothing. It is a bit embarrassing but once it starts the sound makes people look elsewhere lol. Mine seems to do it warm.

 

Well, it's been a few weeks, any updates?

I agree with everyone else, you have to work down the list of spark, fuel, and air. Luckily air and fuel are easy to nail down. Cross those off your list and you might as well replace the plugs while you have the entire front of the engine torn to bits.

 

I would go with the GM. I used the $240 Carquest special and got a year out of it. Have had the GM on there for 5 years now and no problems.

Pete