What the heck is wrong with my baby

[itsafordbaby]

I have a '94 XLT with about 200k. The tranny has been reworked and the whole thing has been maintained very well. A little while ago it the fuel pump start to work only intermittently, so we started searching for problems. We have:
replaced the fuel pump
replaced the fuel relay
replaced the ecc relay
replaced the computer

and it still continues to do it. It used to be that if you would wiggle the relay box it would start, but now that doesn't even work. Because it is my main vehicle and I can't be stranded we installed an emergency switch to the fuel relay and that seems to work, most of the time. Really, the thing is driving me crazy!
If it weren't for that the truck would be perfect. The engine runs so sweet that when it idles, you have to look at the rpm gauge to even tell it is running. We pull our pop-up with it and it doesn't even feel it there. Consequently, I really don't want to give up on it. Please let me know if you can help.
Thanks

 

[Atom Ant]

Sounds like a bad ground. my 2 cents

 

[itsafordbaby]

How do I locate

How do I determine this this or how do I locate the bad ground so I can fix the problem?
Thanks for the quick reply.

 

[mikeinri]

I would start with the relay box. If it used to respond to a wiggle, and doesn't anymore, there's a good chance that whatever was left of a weak connection is now gone. Remove the box, check all wiring, look for weak/corroded connections, etc.

Good luck!

Mike

 

[RyanT85]

also when you find the ground make sure that everything has its own ground it works better if multiple things aren't sharing the same one and make sure to use a washer with "teeth" between the bolt and the ground source. if there is corrosion don't just replace the end, replace the whole cable a lot of the time it is under the coating and you can't see it

 

[Bwana Bob]

Get the schematic or consult the Haynes Manual, etc. and check all connectors between the relay box and the pump. Don't forget the connector underneath, near the spare tire. It connects the harness to the fuel pump power cable coming out of the fuel tank. Look for a corroded connector or loose wires on the backside of the connector.

Bob

 

[mikeinri]

Right, what he said...

I said START with the relay box. Obviously, you should check the whole circuit. Sorry I left that out.

Mike