No start(no fuel pump sound or CEL)

[MrShorty]

If you want to talk about possibilities, I'm sure it is possible for the PCM to just go out like that. Unless something is being miscommunicated, this:

but the fuel pump relay seemed to be getting no power.

makes me believe it isn't in the PCM. As noted, the PCM is responsible for closing the fuel pump relay, but it isn't responsible for getting power to the relay.

1st thing I'd probably do is verify no power to the relay. One lead (Black/Yellow on my '92) is hot at all times. If there really isn't power at this lead, then I'd move up to the next component in the circuit -- the fuse. Is there power at the fuel pump fuse? Is the fuse good?

If there is power at this lead, the next thing would be to turn the key on and check the red wire at the fuel pump relay. This wire comes from the EEC relay and should be hot with the key in "run."

 

[ayyno]

Thanks for the suggestion...but unfortunately I had it towed today to an Electrical Specialty shop, we got referred by a scrap yard owner we do business with very often...hoping not to get screwed...plus left him some notes on things that have been done and whatnot.

I'll be sure to update with a resolution...hopefully ASAP.

 

[ayyno]

Okay, $350 later(towing+repairs)

It was a wiring harness that fell onto the exhaust manifold and melted. Now...I present a new problem now that she's up and running again.

When I turn the key to RUN, the fuel pump primes as always...but doesn't stop. It just keeps running until I start the truck, I know that isn't good for the pump, anybody have any ideas?

Also, I'm still getting no 3-4 shift in OD. TCC still locks up in 3rd in OD, just no 4th shift. Occassionally if I push her to ~75 she'll act like she shifted into 4, but once I hit the gas again she jumps back up in RPMs. Currently I'm getting about 2,500 RPM at 55 MPH. 3,000 at 60. Normally I was at about 1,800 or so at 55. I have 31 inch tires, but this is a new problem...I've had these tires for about a year or so...so it's not a change because of tire size.

 

[MrShorty]

When I turn the key to RUN, the fuel pump primes as always...but doesn't stop. It just keeps running until I start the truck, I know that isn't good for the pump, anybody have any ideas?

I would probably first check for a short to ground in the "relay coil circuit" between the fuel pump relay and the PCM. If there is no short to ground, make sure the relay is working properly.

 

[MrShorty]

Also, I'm still getting no 3-4 shift in OD. TCC still locks up in 3rd in OD, just no 4th shift.

3-4 shift is electronically controlled. I'd start by checking those electronics (pull codes and get a wiring diagram and check the 3-4 shift circuit.).

 

[ayyno]

Thanks for the tips, I'll get back to you when I get a chance to do some digging around.

 

[ZAID*512]

I just fix this problem on my 96 Explorer and it turned out to be the inertia switch that went bad after 15 years. To bad I didn't find this thread earlier when I search fuel pump.

I dropped the tank and verified that I had no issues with the fuel pump since I had a cousin change it out last week. I check all the electrical system for continuity and then finally I found my old tore up Chilton's and saw that there was an inertia switch so I came back in and searched for it and found this thread.

The manual says that the relay gets two voltage signals one direct from the ignition and one from the PCM which checks the inertia switch first. Without both the relay will not work and that is what we were seeing. The relay would not energize regardless of the 12 volts it read at the power box. This was really messing with us because the relay worked fine when we hooked it up with 12VDC from the battery.

Originally the car was dying while driving and then it would start around 15minutes later and run fine for a week. Today it was just cranking with no start and no CEL either. One thing I did find out was that the signal wire from the inertia switch to the instrument cluster was broken out of the harness and that is why I wasn't getting a light on my dash. The manual says that if the inertia switch is tripped you should get a light on the dash.

This thread really helped me a lot so thanks guys.

I hope my post can help someone else.

 

[bushman1950]

1991 explorer wants to start but dies. why .thankyou bushman .winnipeg

 

[Roadrunner777]

Bushman, you will get more visibility to your question if you start a new thread. Also, include any symptoms, sounds, recent work done, all the details. This will help people to help you.