With Warm Engine, Car has trouble getting started

BENJI808

MEMBER
1986 LINCOLN TOWN CAR
5.0L
V8
RWD
AUTOMATIC
200,000 MILES

When the engine is warm, the car seems to have trouble starting: the engine cranks and starts per usual, but then immediately dies. If I press on the gas pedal as I start the vehicle, this does not seem to happen (although it might still run rough for a few minutes), so my guess is it has something to do with fuel getting to the engine. Other than this issue, the car starts, idles, and runs very well. I've considered vaporization, but am unsure if that happens on a non-carburetor engine, and am not sure what steps I would take to fix/check it.

Any direction you can provide would be appreciated. Let me know if you need further information.

Thank you!
Benjamin

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Benjamin:
Do you ever notice any black smoke from the exhaust when this happens? Also, has the check engine light ever come on? II agree, fuel pressure should be checked. Do you need directions? Do you have a fuel pressure gauge? Although the pressure should be checked, I don't feel it is a low pressure problem but rather too much pressure. Perhaps the regulator isn't working properly or drawing fuel through its vacuum supply.

Also, I need to know if the idle is ever unsteady.

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Thursday, October 30th, 2014 AT 8:41 AM

BENJI808

MEMBER
5 POSTS

- I have not noticed any black smoke, or seen the check engine light come on.

- The idle does occasionally rev up and down significantly; the variation seems to occur more often when the vehicle is warm (for example, after restarting following a 3-5 minute sit), but does not seem to affect driving on the road at all.

- I have never tried checking the fuel pressure, but after looking online briefly, it does not look like that would pose much of a challenge.

Let me know your thoughts, and thank you very much for your help!
Benjamin

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Thursday, October 30th, 2014 AT 9:24 AM

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

I have a feeling the idle air control valve (IAC) is an issue. The IAC is responsible for maintaining the engine idle speed. If it goes up and down when warm, that is usually the issue or there is a vacuum leak. Also, if the IAC doesn't allow air into the engine when starting, the engine will become hard to start. As far as driving the vehicle and it running properly, the IAC does nothing other than maintain the idle, so once you are moving, it can't affect the performance.

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Friday, October 31st, 2014 AT 8:33 AM