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help with engine/fusebox

Discussion in 'Stock 1991 - 1994 Explorers' started by Fordexplorerguy1, January 19, 2011.

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  1. Fordexplorerguy1

    Fordexplorerguy1 Active Member

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    Okay so finally i got my fuel pump out of my 94 ex and it works. In the car it doesnt but if i jump it to the battery it works fine. SO i put it back but I bypassed the entire relay to see if my truck would start. Nope. I made sure the fuel pump was running in the right direction and it was. But I had to get a jumpstart because my battery is dead my truck has been sitting since november I did also completely lose track of where the relays go, If thats the problem? can someone show me where which ones go, My truck cranked and cranked but it didnt start. This is really frustrating me and some help would really be appreciatory thanks
     
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  3. trush1492

    trush1492 Member

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    Sounds like you might have a bad ground at the pump.
     
  4. Fordexplorerguy1

    Fordexplorerguy1 Active Member

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    I bypassed the pump and got it working but the truck wont fire, would a bad ground cause that?
     
  5. walterd140

    walterd140 Active Member

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    There is a map on the lid for the relays, but the 1st 4 (closest to the firewall) are the same. I believe the heater blower is top left (closest top to the fender). I turn my blower on high, then put the relays in that socket. If the relay is in & no blower (you can hear it from outside), then the relay is bad.

    As for not starting, is the Inertia switch activated? Did you jar the truck or drop it off the jack hard? Open your panel in the rear interior where the washer jug & jack are. Inertia switch is in there toward the front.
     
  6. Fordexplorerguy1

    Fordexplorerguy1 Active Member

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    no i havnt dropped the truck hard, And i thought the inertia switch was under the floor boards in the front, its a 94 ex
     
  7. 92exp4x4

    92exp4x4 Elite Explorer

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    Inertia switch should be under the dash on the passenger's side. The relays are all the same so it does not matter which hole they go into.

    You could have an issue with the PCM. The computer controls the ground to the fuel pump relay, with the ignition turned to 'on' this ground is completed which allows the relay to close activating to pump.

    I think its a blue wire, but I will have to look it up. If you are not getting a ground at the PCM pin then the fuel pump circuts will not work.
     
  8. Tbars4

    Tbars4 Moderator Emeritus Elite In Memoriam

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  9. Fordexplorerguy1

    Fordexplorerguy1 Active Member

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    So Where would i find the ground to the fuel pump/pcm?
     
  10. 92exp4x4

    92exp4x4 Elite Explorer

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    First of all, have you pulled any codes? Did the pump run when you bypassed the relay? Have you checked the fuel pressure? Should be around 35 PSI. If you can get the pump to run, see if its pumping. Try to open the valve on the fuel rail to see if there is pressure. Just use a small screwdriver to quickly push the pin in the valve (it looks like a tire valve)

    This is a detailed explanation of the circuts for the fuel pump. I'm sorry if its confusing and it may need to be read a few times...

    Pump feed:

    There will be a black/yellow wire that feeds battery positive to the fuel pump relay contacts via a 20 amp fuse. On the pump side of the relay contacts, there is a dark green/yellow wire that ties into the inertia swich. This wire changes to a pink/black wire that feeds the pump motor.

    Ultimatly the ground for the fuel pump itself runs back to the engine bay on the driver's side. Look under the top lip of the fender next to the anti-lock diagnostic connector (red). There will be bunch of black wires that come together and bolt directly to the fender with a green screw. There are various systems grounded here.

    Relay feed (to close contacts)

    The ground side of the relay coil is a light blue/orange wire that ties into the diagnostic connector then into the PCM at pin 22. This is the pin that the PCM grounds (with key on) to activate the relay. You will get a test light to light if its conncted to a battery hot and probed to this pin

    The relay coil gets it's power supply from a red wire coming from the PCM Power Relay. That relay gets its power in turn from a yellow wire via a 30 amp fuse.

    Check codes, there may be a fault code for this circut. The PCM monitors voltage on the pump supply circut and should code if there is a problem.

    I hope this helps you, its actually easier than it sounds. Grab a meter and start checking voltages.
     
  11. tgreene92

    tgreene92 Active Member

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    did you spray throttle cleaner into the throttle body just to make sure its not starting because of no fuel, you could have pulled some relay or wire by accident for the ignition system and not be getting spark. you could have a clogged fuel filter or line, if it was sitting for awhile the fuel could have gummed up somewhere.
     
  12. Fordexplorerguy1

    Fordexplorerguy1 Active Member

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    the truck has been sitting since november, I had to change the valve body And the battery went dead, I bypassed the fp relay and it runs and gets gas up to the fuel rail but when i jumpstart it, Nothing! I have switched all the relays around, so i have no clue which one is bad or if any are and i have not messed with the fuse box, Its hard to check voltages with a dead battery so im going blind Trying to fix whatever may be causing it.Symptoms: Fuel pump Just quit working after sitting and After i bypassed it it wouldnt start and i am getting fuel to the fuel rail as i said earlier,
     
  13. 92exp4x4

    92exp4x4 Elite Explorer

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    Like you said its really hard to diagnose electrical problems with no... electricty.:D

    Is your battery junk? Can it be charged? If its sat for a while discharged, it may be garbage by now. Get ya a good one and start fresh. That will be at least one issue solved, and it may be the cause of other problems due to volt drops.

    If you are getting fuel the only other two things for combustion are air and spark. Pull a plug and see if it sparks while cranking and grounded to the block, just don't have any fuel sitting around when you do it! You may get a surprise.
     
  14. Fordexplorerguy1

    Fordexplorerguy1 Active Member

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    thanks for all the help i fixed it and got my truck running!, It was either a bad ground or a bad pcm fuse, but I redid the grounds and switched the pcm fuse and it worked, This forum has helped so much! Thanks!
     
  15. Tbars4

    Tbars4 Moderator Emeritus Elite In Memoriam

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    ...Glad to hear you are back on the road..:biggthump
     
  16. Fordexplorerguy1

    Fordexplorerguy1 Active Member

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    Now just to figure out what manual transmission i want to swap my failing a4ld...
     
  17. Tbars4

    Tbars4 Moderator Emeritus Elite In Memoriam

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    ...Check the tranny section...

    There are a couple real good stickies that cover that subject at the top of the section...;)
     
  18. Fordexplorerguy1

    Fordexplorerguy1 Active Member

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    Yeah i have been looking at them But I want to go to a manual m50d But im like 15 and I dont have access to the best tools either :(
     
  19. 92exp4x4

    92exp4x4 Elite Explorer

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    It's a fairly involved job with out a good place to work. I'm doing manual swap now plus alot of other stuff while its apart, and hopefully will write a thread about it in the coming months. I'm out of money right now to finish though.
     
  20. Fordexplorerguy1

    Fordexplorerguy1 Active Member

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    Yeah sorry to hear that, My ex isnt Our sole means of transportation, It was got just to tinker on And i was originally gonna fix it and sell it but I think im going to hold on to it, Its just one of those trucks you can go in a lot of directions with.
     

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