fuel problem ....relay?

[mark1799]

hi all just got this 91 explorer ran great for months guy i got it from said he had tapped on relays to get it to run the i had that promblem after a few months he came over we tapped on the relays and just like that fixed for a few weeks then problem got worse so i replaced fuel and eec relay worked great for a week now if i go out for a short time it wont start wiat about ten min it starts ive had problems with aftermarket starter relay on a 91 f150 and thease are aftermarket relays any idears?

 

[MrShorty]

When it won't start, are the relays stuck open? Can you hear the fuel pump prime? Does the CEL come on KOEO (indicating that the computer is getting power)?

 

[Tbars4]

...If it is an autozone relay it is quite possible it is going bad...This link may be of use as it has prices and choices...I think we also chatted about the problems with the short life of the autozone relays...:scratch:
http://www.explorerforum.com/forums/showthread.php?t=208097

 

[mark1799]

well still same problem changed fuel pump worked good foe 2 mounts then problem started again changed fuel pump again same problem about the computer cel coming on ?????????how do i check that? changed fuel pump twice realys twice even went to ford dealer lats time for realys ???

 

[MrShorty]

CEL (Check Engine Light) is lower left corner of the dash, next to the left turn signal indicator. Key On Engine Off (KOEO), that light should come on indicating that the computer has power. If that light doesn't come on, it may be burned out, or it may indicate that the computer isn't getting power, which would contribute to a no start. If it is coming on when it won't start, then go back to the fuel pump circuit and make sure it's intact. Even if the pump is coming on, I would put a fuel pressure gauge on it and make sure the pressure is coming up to spec (40 psi). I recently had a no start on my '92 where the pump ran, but it was only generating 15-20 psi due, apparently, to a clogged fuel filter.

Have you checked for spark when it won't start?

 

[mark1799]

well thanks for all this but i know the pump is not comeing on when it wont start no sound and i hope i got that right to check cpu left trun singnal ? and there is no check e l on god to pumps 4 relays some times it works some times it dont i was also thinking cpu?

 

[MrShorty]

i know the pump is not comeing on when it wont start

I didn't see this expressly stated before. Now that we know it won't start because the pump won't come on, here's what I'd do. Grab a voltmeter and a wiring diagram (The one in Chiltons is adequate if you are good at reading wiring diagrams). Put the negative lead to a good ground. Use the positive lead to work down the fuel pump circuit (starting at the battery). Basically where the voltage drop is is where the problem is. You should know that, even when the relay is open, the fuel pump circuit will show ~6V because of something in the PCM's internal fuel pump monitor circuitry. You can use the fuel pump test lead in the self-test connector to "ground" the fuel pump relay which should close it (if it's working correctly).

 

[mark1799]

well i got 12 volts all the way to the fuel pump harness must be the fuel pump wright even though i changed it twice in 2 mounts called ford dealer got a price for a pump from them could it be the after market pumps are **** ?

 

[MrShorty]

That would be my interpretation, unless there's something wrong with the ground side of the circuit.

 

[mark1799]

well now it just started WTF................ i dont gett it

 

[matt987]

according to ford, the after market fuel pumps have been known to be the cause of that.. i had an aftermarket pump for a while and it fried the pump relay under the hood, so i replaced it with a ford fuel pump and relay and since then it has been fine...