'85 5.0 EFI problem
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Senior User
Joined: Apr 2008
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From: Michigan
'85 5.0 EFI problem
When i start my truck while its cold, it will start and run fine until the warm-up process is done and when it starts to idle lower, it stalls.
And when it is warm, starting is also a problem. It will act like it doesn't want to start, it just keeps cranking. Could that be the coil going bad?
Thanks!
And when it is warm, starting is also a problem. It will act like it doesn't want to start, it just keeps cranking. Could that be the coil going bad?
Thanks!
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
Could be a lot of things and is likely more than 1 thing. Bad idle could be a dirty IAC, take it off and clean with carb cleaner. You should also check the fuel pressure at the rail, if you're not getting 35-40psi when cranking you have a bad pump or clogged fuel filter.
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Tuned
Joined: Jan 2006
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From: Blue Ball, PA
Could be a lot of things and is likely more than 1 thing. Bad idle could be a dirty IAC, take it off and clean with carb cleaner. You should also check the fuel pressure at the rail, if you're not getting 35-40psi when cranking you have a bad pump or clogged fuel filter.
I believe Conanski is right on as how to start trouble shooting. The only thing that I would add is: I had a fuel pressure regulator problem that would allow my engine to start when cold, but after it warmed up during a trip to town; I would park it and shut it down and wouldn't be able to start it until it was completely cooled down. Turned out to be a bad fuel pressure regulator. Very similar to your problem.
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From: Michigan
I believe Conanski is right on as how to start trouble shooting. The only thing that I would add is: I had a fuel pressure regulator problem that would allow my engine to start when cold, but after it warmed up during a trip to town; I would park it and shut it down and wouldn't be able to start it until it was completely cooled down. Turned out to be a bad fuel pressure regulator. Very similar to your problem.
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From: Michigan
I dont know, ive never touched it before. Where is the IAC? Should i clean them both?
Okay, thanks for the info.
Okay, thanks for the info.
Tuned
Joined: Jan 2006
Posts: 263
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From: Blue Ball, PA
The IAC is bolted onto the side of the throttle body. It has a shape of a small cylinder with an electrical plug on the end. If you haven't touched them before and it has some miles on it (whose truck doesn't, especially our years); its time for a good cleaning. Clean both the throttle body and IAC. You need to remove the IAC to clean it properly; and use a tooth brush with the throttle body cleaner if needed to get them both clean. I noticed a huge difference in idle quality and low speed driveability after cleaning them.
Elder User
Joined: Jan 2009
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From: East Tennessee
The TPS caused those exact symptoms for me. I had to unplug it to crank it, then plug it back in after it was running. I replaced the IAC first, didn't change a damn thing. When warm, when unplugged, does it idle really high, but run a lot better?