QuestionI had this problem last summer, it went away all winter, now with the warm weather, it started again. Sometimes when I turn the ignition key, dash lights are very dim and engine turns over OK but won't start. Sometimes it starts OK & will stall-out braking for a light, taking off from a light or even upon (usually) letting off the gas at highway speeds. Sometimes it just instantly cuts out & back in while driving. Also, bumpy roads don't seem to cause a problem or gently or not so gently jiggling the ignition key while driving does not seem to make it happen.
AnswerRon:
It almost sounds like multiple problems, some of which seem almost contradictory. For example, "dim lights" suggest low voltage, i., e., a weak or half - dead battery. But you can turn the engine over with it so it must be ok. Thus its difficult to pin down a probable cause that satisfies both observations. One possible cause would be a poor electrical connection (high resistance) in the circuitry leading to the keyswitch and thus all the control circuits, except for the high-current starting motor. But that would not generally correlate with the winter-summer observations!
The second symptom, stalling out, sounds like a problem in the fuel system..fuel mixture too lean at idle when warm. So, for that I would check the various fuel delivery and control items such as temp sensors, automatic idle control valve, fuel pressure regulator, etc. I would focus on the idle control area.
The one consistent observation seems to be ambient temperature; the fuel mixture is controlled to be richer at cooler temps...so that "fits".
Have you the tools needed for such a checkout, including a good book? If you need specifics as to the checkout & diagnosis, I can send you mechanic's manual excerpts. Also, for an investment of $25. per year, you can subscribe to an online source of professional level info for any repair you can imagine, specific for your vehicle. Its truly complete!
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Hope this helps,
Jerry
