AIC going bad? Or bad fuel pump?

[ezjam]

Hi and thanx to all who respond.

http://www.acequality.net/temp/explorer01.jpg
http://www.acequality.net/temp/explorer02.jpg

I have a 1994 Explorer that has started acting up. When I turn the
key to the on position, this cylinder clicks repeatedly 5 to 10 times
in a second or two and then it stops. Sounds exactly like a relay
closing and opening over and over again. This behavior might be
normal, however I just noticed it because my explorer all of a sudden
runs very rough. When idling, the RPM's vary between 600 to 1400
constantly up and down for as long as the engine is running and
sometimes, it will die. Runs so rough, it cannot be driven.

Also worthy of mention is the fact that my fuel pump does not run
every time I turn the key to the on position. I would say it only
runs about 50% of the time with it sometimes running 5 out of 5 times
and other times it not running 5 out of 5 times. Also, when the fuel
pump does not run, my Explorer will not start.

Is the fuel pump supposed to run every time I turn the key to the on
position? Or only if the pressure is low?

At any rate, any help is greatly appreciated.

Thanx in advance.

jg

 

[Turdle]

Here you go-try this-
http://www.explorerforum.com/forums/showthread.php?t=84220&highlight=IAC+valve

tha IAC is sticking-if cleaning doesn't fix it you should replace it-
It is the cause of the stumbling idle-

For the fuel pump issue, to troubleshoot this, check if there is power to the pump when it isn't working

 

[dogfriend]

If I recall correctly, on the 1st Gen Explorers (91-94) the fuel pump gets its power from the Fuel Pump relay which in turn gets its power from the EEC power relay. In other words, for the fuel pump to work, both relays must be working correctly.

I would check both the FP and EEC power relays located in the Power Distribution box under the hood.

The IAC is a possibility for a loping idle. My 89 Ranger had this type of idle problem when one of the vacuum plugs fell off the intake manifold; you may want to look for a broken/ missing vacuum hose.

 

[mawrazen]

Ditto on a vacuum leak.

 

[ezjam]

Here you go-try this-
http://www.explorerforum.com/forums/showthread.php?t=84220&highlight=IAC+valve

tha IAC is sticking-if cleaning doesn't fix it you should replace it-
It is the cause of the stumbling idle-

For the fuel pump issue, to troubleshoot this, check if there is power to the pump when it isn't working

I did as suggested by your link. No joy. Engine is idles irregularly. Thanx for you answer though.

jg

 

[ezjam]

If I recall correctly, on the 1st Gen Explorers (91-94) the fuel pump gets its power from the Fuel Pump relay which in turn gets its power from the EEC power relay. In other words, for the fuel pump to work, both relays must be working correctly.

I would check both the FP and EEC power relays located in the Power Distribution box under the hood.

The IAC is a possibility for a loping idle. My 89 Ranger had this type of idle problem when one of the vacuum plugs fell off the intake manifold; you may want to look for a broken/ missing vacuum hose.

I swapped out both relay. FP with a new one that I had purchased just for this task and the one from the AC fan. No joy.

As for the vacuum leak... where to begin. There a about a dozen hoses scattered around the engine. Most are rubber but a few are thin plastic (who ever came up with that idea?)

Any pointers?

jg

 

[ezjam]

Just as an FYI in case anybody else ever runs in this problem... After many hours of fiddling, the problem turned out to be the on board computer. Replaced that and all was well again.

thanx to all for your help.

ez

 

[MrShorty]

If I may ask, what led you to believe the PCM was bad? They don't go bad very often, and a bad PCM is probably as difficult to diagnose as anything in the engine management system. Any help in learning how to diagnose a bad PCM would be useful.