Have a 94 Explorer 4.0 which occasionally wo'nt start (because I can't hear the fuel pump) after 10-20 minutes of waiting the engine will start. A new fuel pump was installed to try to correct this. 190k. Does anyone have an idea of where to check further ? Thanks for your help.

 

Replace the fuel pump relay. It's in the power distribution box under the hood near the battery. $10 part. When you turn the key on (but don't crank), you should hear the fuel pump run for a couple of seconds. If not, then the problem could be the fuel pump relay or the inertia switch. Since you have already replaced the fuel pump, I'd start with the relay.

 

Will try that. Thanks for your help.

 

Two days without a problem. Thanks again.

 

After 10 days without a problem, it would'nt start.OK after 10 minutes. What should I try next ?
Thanks

 

When it wouldn't start, could you hear the fuel pump prime?

 

No, it was the same as before exactly (no pumping sound)
Thanks

 

If you are certain you changed the fuel pump relay, change the EEC power relay next. If EEC is failing to power at times, it will not drive the fuel pump relay to turn on, not to mention the other EEC functions.
Dialtone

 

Will try that. Thanks for your help.

 

I'm having the same exact problem with a 1994 Explorer. Apparantly, this random starting issue is very common with the Exporer and so far, I cannot find anyone that has figured out precisly what is the cause.

I've changed the Fuel Pump Relay and that didn't help. I have purchased a replacement fuel pump this weekend, but have not installed it yet. I would like to try other likely/easier remedies.

Is the EEC power relay in the same location as the fuel pump relay? What function does the enertia switch serve and how can you tell if it is bad/going bad?
Leisureman, did you change the fuel pump yourself? If so was it difficult? I was actually searching this Forum for information on changing the fuel pump when I found this thread.

 

1. EEC power realy is in the same area as fuel pump. To my knowledge, ther are 3 realys there with the 3rd being the WOT (Wide Open Throttle). The computer controls this relay in response to detecting hard acceleration to disengage the AC compressor clutch.
2. The inertia switch is designed to disconnect the fuel pump power in the event of a crash. This stops the possibility of a fuel spill and fire after such an event. It can be reset after a minor bump. Generally, it is either on or off, so should not be the culprit in an occasional no start condition.

[/QUOTE] Leisureman, did you change the fuel pump yourself? If so was it difficult? I was actually searching this Forum for information on changing the fuel pump when I found this thread.[/QUOTE]

I changed mine on my 91. Most difficult part was removing the rusted bolts that secure the protective steel bottom pan. Soak them all down with a good rust solvent the day before you start and it should make things easier. Also dropping the drive shaft helps to get better access to the tank strap bolts. I removed the left rear wheel and dropped the tank down enough to R&R the pump without actually having to get the tank all the way out from under the vehicle. The frame arch over the back axle gives enough access to work on it thu this opening. You will need the special tool to remove the push-lock in fuel line fittings. You may also need to soak them down with the rust lube as they tend to get cranky to remove, from rust and dirt that accumulates inside the spring locks. It also helps if you can enlist a friend, as it is hard to hold things up and start the bolts when re-installing everything. Of course, drain the tank first as you do not need to wrestle with the extra weight of the fuel.

Dialtone

 

Dakaty,

The EEC relay is in the same fuse box as the fuel pump relay. The lid of that box showes where it is.It was the same cost ($11). I had to pry it up as it was stuck.So far after 3 days no more trouble. Evidently the signal did not get from the EEC to activate the pump.

When this first happened last summer I thought it was the pump so had it replaced. I changed one myself on a LeSabre which wasn't too hard to do,but watching the folks do the Explorer...I wouldn't want to tackle it.

Good luck.

 

I had the same no start problem on my '95 XLT. Replaced the Fuel Pump Relay which fixed it. Then it stopped working again. It would crank but not fire. I checked the relay that I had recently replaced and replaced the EEC relay but they didn't help, so I just started checking fuses. It turned out to be the PCM fuse! This may be the cause of some other's no start issues.

 

Hey! A new clue!!

What is the PCM and where is the fuse?

Thanks

 

PCM = Powertrain Control Module. aka engine computer aka EEC-IV computer aka EEC computer (you get the idea). The fuse should be in the power distribution box under the hood next to the air filter housing (the same power distribuition box that houses the relays that have been discussed extensively).