Ok, this is gonna be long, but have to give full story, so to better help figure out problem. Round Jan. this year got new panhard bar put on my car. It sat for bout a month and a half then I finally picked it up. It was low on gas all that time it sat. From Jan. til about a month ago, no probs except sometimes the service engine light would flicker on then off. So, about a week ago, I came home from town. Everything, temp, volts, oil and gas all were perfect. Turned the car off and then about 10 minutes later went to leave again and the car was just sputtering and died. The more times I tried to start it the less amount of time before it died until finally whouldn't start at all. So, let sit all weekend, with about 3/4 tank of gas. Came home, tried it. Started right up. Drove home to work and back 3 days in a row, perfect. Then one day went into town, and it happend again. So let sit about an hour and a half and it started right up and took home. Put on new fuel filter and had a pressure test done on pump, and was great. Worked fine all day yesterday and today. Then went into town again tonight and same damn thing happend, let sit about an hour, started right up, got home, turned off. Tried, no go. So wtf is wrong? I'm goin crazy here! Please HELP!! Open to any suggestions, but i'm no mechanic, so some stuff I may not be able to do myself.

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86' IROC-Z
5.0L TPI
Spohn panhard bar and LCA's

 

Check the impedence of your injectors when it is running bad. I had the same prob, when it sat for a while if ran fine because you injectors checked out ok but when it ran bad 5 injectors had a very low inpedence.

 

I can't keep it running long enough to do that. It usually does it after it gets warmed up really good. Could it be some sort of sensor? Or crap in the tank?

 

Couple a things come to mind, when my fuel pump went out, it did some random stuff like your describing, and the pressure was good at the fuel rail.

When stuff gets hot it expands, which may be why it starts after you let it sit for awhile, now you just have to narrow done which part.

Do our fuel pumps use the gas for lubrication or cooling? I had a delta 88 that my dad let run out of gas and it fried the pump, maybe letting it sit for so long produced some build up in the pump or something.....just a thought

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1986 Trans Am
305 TPI
"If it's not one thing, it's another!"
http://www2.hanover.edu/hierlmeier

 

Maybe you should check those codes you were getting and post them. Does it start and then die? Is it a starting problem, or a running problem? Try disconnecting the MAF and see if it will start/run.

 

Rezinn:
Ok, not sure what codes you mean. At first when the problem happens, it runs, but really choppy. Then dies after a few seconds. Then, i'll try again, and same thing. Maybe be able to run 3 or 4 times, until finally won't start at all. Can't hear the fuel pump engage or anything. MAF sensor has to be good, just got it put on in Jan. also. Forgot to mention that, sorry.
86 Trans am:
I think you may be right on the the hot/cold thing. Maybe when it gets warm, it expands and something happens and it won't start and stuff. But, after it cools and contracts, it works again.

 

Yeah, MAF may be good, but the relays may be bad. If you d/c it and start, and your problem is gone, replace the relays.

You said the service engine light flashes, that means that the ecm has stored trouble codes. Find your ALDL under your steering column, connect the upper right to terminals(side by side top far right) and turn the key onto accessory mode and it will flash lights. Count them(sorry if you know this) in sequence, at first a 12 should flash, followed by trouble codes. You can look up the codes at the mainpage of www.thirdgen.org at the bottom in red to find the problem.

The fuel pump DOES use gas for cooling. You say you can't hear the fuel pump engage, this is normal because it has already primed to pressurize the lines.. but will the starter crank after a few tries?

 

Ok. The service engine light has not flickered for about a month and a half. This problem happend this past week. My fuel pump usually depressurizes after about 5-10 minutes, then when I turn the key forward I can hear it engage again. But, when the problem happens and I let it sit for 20 minutes at least, it still doesn't engage. After about an hour or more, then it usually starts right up. Could it be some sort of sensor?

 

Please clarify..whenever you can hear the pump prime, the car WILL start? But then sometimes it won't prime and therefore WONT start?

 

Normally before the problem started it would prime itself when started, then when shut off it wouldn't prime again until the pressure went down (which was usually 5-10 minutes). But, it would still start again if I tried right away. Now since the problem has been happening, it will prime and start once warmed up, but when it is shut off won't prime again even after sitting 20 minutes. And will start, run choppy and die in a matter of seconds 2 or 3 times, and then after that not start at all. After about 1 or 2 hours of sitting though, it starts right up. When it won't start it still cranks over fine and everything. And the check enine light does not come on or anything.

 

This problem sounds very familiar to what I have to deal with right now. But fortunately you can still drive your car.

I swapped from carb to TPI about a month ago now and it ran good for about 2 weeks, then one mourning... nothing. Like you said it would idle for a few seconds then just plain die. With my problem I have a constant SES light but it wont flash any codes, just on all the time, along with the fan! For more info look at my other post on this board

"Help, constant SES light, no codes and engine wont run".

I do get fuel pressure, and power is good all the way around. But just as a note my fuel pump doesn't always turn on right away. It is almost like an ignition timer. If I turn the key and the pump turns on then it wont turn on the next time I try unless it has been after a certain amount of time. It might be something you should look into, try the fuel pump relay, it's wires and even the connection that goes right to the tank... assuming you pump doesn't turn on all the time.

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'86 TA, T-tops, T-5, 3.73, 4 wheel disks 350, compucam 2040, performer intake,SLP Headers, 3" race magnum muffler, 1.6 Comp rockers, Ripper shifter, perf. friction pads, Hypertech ignition, Earls brake hoses, Hotchkis springs, Tokico Illumina 5 adjustable shocks and struts, Lakewood panhard and trailing arms
14.50@ 97 with carb... now converted to TPI

[This message has been edited by slowTA (edited August 06, 2001).]