1993 Explorer XLT fuel pump issue.

[scasterline]

B+ at ??

Shorty:

B+ was connected by me to the AC Clutch, not the WOT relay, sorry I confused all. I was just checking to see where I actually had any volatges and what they were on whatever connectors, and I checked the AC connector and had nothing and I knew that or thought that the the AC/WOT
relay might control that, so after nothing found, I put ground to one side of the compressor clutch coil and B+ to the other and the clutch locked in, so I
knew that there was a voltage missing from the AC circut.....question is why?

I am wondering if the fuel pump itself may be the problem, it is loud. I put carb cleaner in the intake yesterday and the 4.0 will run for a few seconds,

 

[MrShorty]

so I knew that there was a voltage missing from the AC circut.....question is why?

There are a few components upstream of the compressor clutch that control power (main switch, low pressure switch, WOT relay). You would need to get a wiring diagram, locate each component and determine where the break in the circuit is.

I am wondering if the fuel pump itself may be the problem, it is loud.

A loud pump can be a problem, but it would not have any bearing on whether the fuel pump relay opens or closes. If the relay isn't closing, a new pump isn't going to help the relay close when it should.

At one point, you indicated that you could ground the test lead and the fuel pump would run. That suggests to me that the electrical circuit is intact. If I wanted to test the pump output, I would put a fuel pressure gauge on the fuel rail, run the pump, and see if it can generate sufficient pressure. Without the engine running, that's about as much as we can do to test the pump.

Here's a quick test: put the positive lead of a voltmeter on the coil ground for the fuel pump relay, negative to ground (essentially measuring the pressure drop across the PCM). Turn the key on and see if you can see the "switch" inside the PCM change state. Your voltmeter should show +12 V when the switch (and relay) is open, 0 V when the switch (and relay) is closed. This should give you an indication of whether the PCM is trying to command the fuel pump relay closed or not.

 

[scasterline]

Check the PCM relay.

I took the dash apart and the bulb is good what else would stop the CEL from coming on?

 

[BWTGUY]

The thirty amp fuse (#1) in your under hood power distribution box hides a dirty little secret. Under the fuse is the fuel pump relay! Try removing the fuse, wiggling the relay, and see if this allows the pump to start.

 

[MrShorty]

what else would stop the CEL from coming on?

KOEO, the CEL is supposed to come on to indicate that the PCM is ready. Without trying to go back and look at what you've checked and haven't checked, things that will prevent the CEL from coming on KOEO:

1) bad bulb
2) broken wire/bad connection between PCM and bulb.
3) bad connection/broken wire or other interruption in PCM power supply circuit (including a bad relay, blown fuse, bad ignition switch).
4) bad connection/broken wire in PCM ground(s).
5) internal PCM failure (I don't do much with solid state circuitry. Someone who know their way around the internals might be able to talk about which IC or what have you that would fail).

Off the top of my head, that's all I can think of. I can't remember how well you've looked at each of these items, but it seems like you've looked at several of them.

 

[scasterline]

Pcm

Shorty:

I would like to thank all of you for the responses I received. I researched
through all of the leads you all gave me and finally (frustrated) I decided to take the computer out of the Ex and remove the cover. I found the problem I think.. In the front left side (connector facing you) it looks like a bomb went off. There is a capacitor that looks swelled and a small resistor that
popped, and the area is all black inside.

I will try to post a pic of it. Not sure if I can post it on here till I join or not.
I will join next month, as I am disabled and spent most of my money this month on code reader and hoses, relay etc.

I am looking for a replacement PCM and will come back and advise the
progress after I get a new or used one on. THANK YOU ALL...

 

[BrooklynBay]

Thanks for the update! Try to determine which section this part of the pc board is connected to, and trace the connections to the main bulkhead connector. It will tell you what is on that circuit. Something external probably shorted the pc board, and might blow out a new PCM if you plug it in.

 

[scasterline]

Ford Explorer Success

Welcome to this forum! I've moved your thread into the stock 91-94 section. Do you see a check engine light turn on when you turn the key?[/QUOTE

After using all the data from you all I successfully got the EX running again!
I learnt a lot as I backtraced wiring and bulbs and relays and grounds and connections and relays and shorting bars, etc. I also discovered that my fuel pressure regulator had no vacumn hose on it, probably for the years I haqve owned it. Fixed that also.

First started up after install of new computer,,,140.70 Advance Auto Parts.
1 Year Guarantee, ran but not perfect, engine light on, wife told me I didnt put the breather intake back on, so did that restarted and ran beautiful/

Took down road at about 20 - 40 mph for about 3 miles stop signs, etc, opened up to 55 for about 4 miles, and then went back at 55 mph. Great
Job. I cant figure what caused it to go out though unless it was the fact that the computer was 17 years old. Air conditioner still dont work ..next
repair..did fidn that the two wire at the Cranksensor were brittle and oil soaked. I need to do valve covers, that is where my oil has been going.

Any rate than you all and I will monitor maybe I can help one of you one day.
I can take photos etc,,,, Thanks Again

 

[Theguy155]

i was having the same problem with my '93 sport, except the fuel pump wouldn't turn OFF when i turned the key on, finally found out it was the computer, now I am about to replace it, got any tips scasterline? i'll probably get mine from advance auto as well

 

[BrooklynBay]

Check the fuel pump relay before you replace the PCM. The contacts could be stuck in the closed position.

 

[Theguy155]

Check the fuel pump relay before you replace the PCM. The contacts could be stuck in the closed position.

Unfortunately, I replaced the fuel pump relay already. It acted the same way.

 

[scasterline]

Fuel Pump Stuck

i was having the same problem with my '93 sport, except the fuel pump wouldn't turn OFF when i turned the key on, finally found out it was the computer, now I am about to replace it, got any tips scasterline? i'll probably get mine from advance auto as well

What method did you use to determine it is the computer? I would check all wiring related to the fuel pump relay. Especially grounds. Also at the ecc test point, as if it closes the circut there it will run continously. I discovered
several oil soaked spots on wiring on mine and brittle insulation that had allowed a short at the crank sensor. I realize that is not the area but it is a
deep suggestion. Also check the grounds at at the computer itself. Above the computer there is a ground connection, also check the grounds inside the
computer plug iself. Advance has the best price for the 1 year warranty. Just out of curiosity, unplug the crash swith and see if the pump still runs.
Follow the posts in my sessions and there is a lot of valuable info. If you need more just ask. I will try to help

 

[Theguy155]

At first I tried pulling codes from it by jumping the EEC test plug, it gave me no codes whatsoever, and I definitely jumped it correctly, this indicated to me that the computer was in fail mode, which to me meant the computer doesn't work anymore. I currently do not have a voltmeter or any other tools besides a screwdriver, so, I took it into the shop and they confirmed that the computer is broken and I need a new one.

 

[scasterline]

Fuel Pump Issue

At first I tried pulling codes from it by jumping the EEC test plug, it gave me no codes whatsoever, and I definitely jumped it correctly, this indicated to me that the computer was in fail mode, which to me meant the computer doesn't work anymore. I currently do not have a voltmeter or any other tools besides a screwdriver, so, I took it into the shop and they confirmed that the computer is broken and I need a new one.

Ok that makes sense. Make sure there isnt a short on the coil side of the relay to ground. If you unhooked the battery at any time before you did the code test you may have erased all the codes from the computer. I did that.

Just make sure, battery is unhooked, both terminals. for a time before you install the new computer, Then put positive term on and then negative.
Again though check ALL wiring on engine area and distribution box before new install. The relay has the schematic on it as to ground, etc.
Let me know.........

 

[Theguy155]

excellent, thanks for the info, will update soon

this is my only car as well, so it is imperative that I fix it

 

[Theguy155]

Alright gents, here we go, the day of reconing is here! The new PCM is waiting for me at Advance, going to go install it after work today, will keep you all informed. Man I hope this fixes the problem.

 

[Theguy155]

one more question for you if you dont mind, scasterline, did you ever find out what caused your EEC to short out?

i have looked at my wiring, realys, fueses, grounds, short bars, etc etc... and everything looks good as far as i can tell, i haven't actually put a voltmeter to it, but i beleive the shop did and i am going to ask them about that today when i pick it up, it has been raining around here a lot, and i am wondering if my PC shorting out had anything to do with water somehow getting inside the cab to the computer or one of its connections

 

[Theguy155]

alrighty gents, the new ECU came in today and is now installed, started her up and the CEL was not on and all of the symptoms were alleviated, drove her around for a few miles and she did just fine, good power, good idle, no stalling, easy to start up, fuel pump runs for 2 seconds

i took a look inside the old EEC and everything looked fine to me at first, i could see nothing that was wrong with it until i found 2 capacitors that both had one of the wires pretty much eroded completely, it wasnt even wire anymore, it was just black goop between the actual board and the capacitor

thanks to all once again for your replies and support

 

[BrooklynBay]

Thanks for the update!

 

[BigDayn22]

what did your problem end up being I am having the same problem with a 93 explorer