Delayed start problem

nrs · 2007-09-26T15:21:41+00:00

My '95 2.5 AX5 YJ has a strange problem, usually in the morning whenit is cool. When the key is turned to run, the check engine lightdoes not turn on right away. There is a delay of a few seconds andthen the relays in the power distribution box under the hood start toclick rapidly. Once this happens, the fuel pump runs for a shortwhile and the jeep can be started. It seems like the computer is notaware right away that the ignition has been turned to run. If Iimmediately turn the key to run again (after first returning it tolock) the check engine and fuel pump turn on normally. After lettingthe jeep sit turned off for about 5-10 minutes, the problem willreturn. Later in the day when it is hot, this almost never happens butit does once in a long while, usually after sitting turned off for atleast a few hours. What could be causing this? What could cause it towork fine on the second try?Thanks

Sep 26, 2007 25 Replies

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Mike Romain 18 years ago

I live in the rust belt in Canada.

Rusty connections are 'very' temperature dependent and one always finds out the battery connections need cleaning after the first cold snap, never before.

Have you check the computer's plug for a green pin or green socket? A green stain means a corroded connection.

The oxidized fuse leg is also very common up here. My wife and I were just comparing notes on that and I think we have had 4 vehicles in the last 20 years that had that 'no start and no lights' issue including our Cherokee. On one Volvo 240 is was the fuel pump fuse, the others were low power ones like for the ignition module.

Mike

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nrs 18 years ago

Although I live in Monterrey, Mexico my jeep comes from Pennsylvania so it has seen it's share of snow and rust! I checked the PCM connector this morning and nothing looked green. I still need to re-check the fuses although I did take out and replace every one. I sure hope it isn't the PCM. Thanks

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Earle Horton 18 years ago

Power to fuel pump? That's just something I thought of. From the manual I have, it looks hard to get to. There's a check valve or something, where the fuel rail pressure can leak down too. It would at least be interesting to put a pressure gauge on the fuel system and see what it does when all this is going on. We're looking for something that deteriorates with time. Once an AC mechanic told me that O-rings can shrink and leak refrigerant in the cold, then be OK at normal temperature. He was pulling my leg, just too stupid and lazy to expose the rear AC unit, but it bears some thinking.

Cheers,

Earle

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nrs 18 years ago

I took it to the dealership today for diagnostic check just to make sure but at this point I'll most likely have to buy a computer.

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nrs 18 years ago

It also crossed my mind that maybe the fuel pump or something else in the system was loading the electrical system, causing the delay somehow but I think that would probably blow a fuse first which it has not done.

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nrs 18 years ago

The dealership confirmed it is the PCM. I'll be looking for a cheap used PCM now. Thanks for all your help.

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