I have a 95 ranger (4.0) that starts up fine when it is cold, but sometimes when I start it up after it is warm it idles very low and erratically to the point it often will quit. When this happen...maybe 40% of the warm start ups, I have to rev it up right away and then it straightens out. All other situations it always runs fine when cold and hot after the initial start up.

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I have changed the plugs. The fuel filter was changed about 40K miles ago. Any other suggestions would be appreciated.<O></O>

thanks,<O
Hartwa<O
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If I had to venture a guess, I'd say you either have a fuel delivery problem, such as a bad fuel pressure regulator or check valve, or your ECT is messed up and not telling the computer that the engine is warm.

If you could do a fuel pressure check that might help the diagnosis, especially if you can get a reading while the problem is occuring.

Also, pull the vacuum hose off the the FPR when the problem occurs and see if there is any fuel in it.

 

I'll check the pressure tonight when I am home from work. I imagine there is a gauge that I can buy that is made to check fuel pressure??? Any idea where the valve is to check it?

Thanks for your help.

 

You can get a fuel pressure gauge at most any parts store. The valve you want looks very much like a tire stem valve, it is located on the fuel supply manifold (the fuel supply manifold is the metal part that's in between the upper and lower intakes.