94 won't start

[94bauer]

I have been having a problem that acts like vapor lock where the truck will occasionally not start. I replaced the fuel filter and pump and things were fine for a week, but now it quit again. When I turn the key forward, I do not hear the pump running. Is there a relay that could have gone bad or could this be caused by a bad crank sensor?

 

[pj8847]

Pump relay would be my first check, swap it out with another one like the WOT relay ( should be the same ) and see what happens.

 

[94bauer]

Is the relay located in the high voltage box under the hood ? I will definetly try that before spending $56 on a new crank trigger.

 

[pj8847]

yes sir, relay is located in the power distribution box under the hood.

I don't think it would be the crnk sens. seeing that when turning the key on you don't here the pump energize. Definitely sounds like the relay.

 

[94bauer]

I went after work and bought a new relay, went back to where my explorer quit, decided to give it one more try before replacing the relay and the stupid thing fired up immediately and ran great all the way home. The problem seems to be heat related. It normally starts when it is completely cool. acts like vapor lock if that's possible in a fuel injected system.

 

[BlakeLong]

I just signed up for this board because I'm having the exact same problem. Seems like only during the heat of the does it not want to crank.
Within minutes of posting this I replaced my fuel filter and it won't crank at all. I'm not sure if it's due to the same problem I started with or if there is an extra step in replacing the filter I missed. Is there some way I need to put back in the little bit of fuel that drained out while I was replacing the filter? I bacically took the old filter off and put and new one on and tried to crank it and it wouldn't start. I'm dumbfounded.
By the way, I caught hell trying to get that filter off!! And I the the special tool!

 

[pj8847]

Ok, just to clarify, it won't crank? or it won't run?

Does the motor turn over when trying to start, or is there nothing at all?

 

[94bauer]

Blake,
If it won't crank then it sounds like a starter problem. If it cranks over but won't start then it sounds like the problem I am having. Your did the filter change correctly, you take the old one off and put the new one on, that's all.

 

[BlakeLong]

When I turn the key, it trys to start, but it won't totally turn over and stay on. Real random thing. After reading some of the other treads, I think it may be the relay.

 

[94bauer]

I replaced the fuel pump relay today when my explorer wouldn't start. It still wouldn't start with the new fuel pump relay. I put the original pump relay back in place and swapped the EEC relay for the new one, BINGO it started right up. Just to double check, I put the original EEC relay back in place and it would not start. I replaced the EEC with the new relay and so far it starts fine when it's warm. I'll keep my fingers crossed.

 

[pj8847]

Glad to see you seemed to solve the prob.

those relays always go out. I replaced mine recently as well, but not with the oem. I used heavy duty high amp Bosch relays.