95 Ford Explorer, intermittent starting problem troubleshooting

[s7efen]

Hi, new here. Also don't know much about cars.

Issue is very intermittent. Have gone weeks without a problem, other times it will occur almost every time I try to start within a short period of time after first experiencing the problem.

Here is what happens normally:

When I turn the key on I can hear the fuel pump "engaging". "check gauge", "check engine", seatbelt light are all illuminated. Turn key, car turns on.

When I am experiencing the issue:

I turn the key. "check gauge" and seatbelt light are illuminated. The "check engine" light is not. I do not hear the fuel pump engaging. I try to start and it cranks/turns over but does not start (http://www.youtube.com/watch?v=064Ilsz8Fzg&t=0m15s) is basically what I hear.

A friend of mine who knows slightly more about cars says it sounds like it is not getting any gas. Which after figuring out the whole " i can / cannot hear fuel pump engaging " makes me think that the problem is the fuel pump.

Has happened countless times over the year I've owned the car. Have brought it into a mechanic but I've never been able to replicate the problem except for once when I've had it there, and his solution was 100% just get a new fuel pump.

I know for sure it is not the shutoff switch.

I have replaced the fuel pump relay switch.

I have NEVER had a problem starting cold. Always when I go to start after driving for a period, turning car off then attempting to start within a short period after.

Apparently if it's an electrical issue there is another switch that could be failing that would cause problems with the fuel pump relay (which might be indicated by the lack of the "check engine" light being illuminated when the pump fails to engage.




I've done a lot of internet searching.

http://www.explorerforum.com/forums/showpost.php?p=2941114&postcount=15

This describes my issue exactly, but there is no confirmed solution in the thread.

http://www.explorerforum.com/forums/showpost.php?p=3001394&postcount=18

Describes a possible fix but I have no clue what to look for when I get under the vehicle unless I have a picture of what to look for.

http://www.explorerforum.com/forums/showpost.php?p=3464677&postcount=27

Possible fix, but again I have no clue what this is or how to clean it.

Found this:

http://www.explorerforum.com/forums/showpost.php?p=3366476&postcount=5



http://www.explorerforum.com/forums/showthread.php?t=266297

http://www.explorerforum.com/forums/showpost.php?p=2656381&postcount=5

So I think my next step is to replace the PCM power relay given the similar cases, correct? Given the condition of the no "check engine light" into no pump noise into not turning on but cranking/turning over.

I'm really trying to avoid the "replace fuel pump, still have problems" thing that seems to be very common when mechanics/dealerships default right away to a new fuel pump. And given that it reliably starts 9/10 times I think that the fuel pump is fine(?) I assume if it was needing to be replaced it'd literally never work, as well as fail on startup sometimes.

Advice? How easy is replacing the PCM?

 

[s7efen]

bumping this, going to try replacing PCM

 

[gatzdon]

Did you check the engine coolant temperature sensor (the one for the PCM, not the console gauge).

You can pull it and measure the resistance across it. I've seen several threads now where the issue can be caused by the PCM thinking the engine is still cold, but not enough to turn on the MIL.

Unfortunately, you have a 95, so you don't have OBDII. Don't know if there's a way to get the temp value from the PCM (easiest way to check).