1992 Ford F-150

Tiny
RICKCINVA
  • MEMBER
  • 1992 FORD F-150
Electrical problem
1992 Ford F-150 6 cyl Two Wheel Drive Manual

My 92 ford f150 with inline six just quit running, no power to the fuel pumps but I can make the run by running wire straight to the pump from the battery, also have no spark at the plug wires, have checked all relays and they check out good also have power to all relays, computer or ignition control module maybe? Any help will be appreciated greatly!
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Thursday, September 30th, 2010 AT 8:00 AM

20 Replies

Tiny
WRENCHTECH
  • EXPERT
Your going to have to test a couple more things.
Are you sure that the pump doesn't run for even 2 seconds when the key is initially turned on?

Do you have power to the coil and injectors with the key on?
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Thursday, September 30th, 2010 AT 8:34 AM
Tiny
RICKCINVA
  • MEMBER
No the pump does not run at all when the switch is turned on. And no I have not checked the power to the injectors. How do I do that. THANKS FOR YOUR REPLY! And yes I do have power to the coil.
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Thursday, September 30th, 2010 AT 8:49 AM
Tiny
WRENCHTECH
  • EXPERT
With a 12volt test light.

Make sure your right about that 2 second period so we don't waste a bunch of time for nothing checking the wrong stuff.

Also check your Inertia switch on passenger side, behind the right kick panel to see if the red button has popped up. Check for the 2 second power coming in there also.
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Thursday, September 30th, 2010 AT 8:54 AM
Tiny
RICKCINVA
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I am sure about the 2 second pump energized sequence and yes I have checked the inertia switch it is not tripped. THANKS!
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Thursday, September 30th, 2010 AT 11:54 AM
Tiny
WRENCHTECH
  • EXPERT
Here is the wiring diagram. Check all your fuses with a test light and test the relay socket to determine if it's getting all the correct triggers. Let me know if you have any questions about the diagram. Be sure to use a computer safe testlight when you start probing that relay socket.
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+1
Thursday, September 30th, 2010 AT 12:02 PM
Tiny
RICKCINVA
  • MEMBER
Ok here is what I found. Fuel injectors test ok.I used your diagram and tested all fuses and the diode tested ok.I then tested the eec socket then replaced the relay and tested the wires under the box. Did the same with the fuel pump relay with the eec relay back in place. Here are the results.
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Thursday, September 30th, 2010 AT 1:36 PM
Tiny
WRENCHTECH
  • EXPERT
Results?
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Thursday, September 30th, 2010 AT 1:40 PM
Tiny
RICKCINVA
  • MEMBER
Having trouble uploading the diagram
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Thursday, September 30th, 2010 AT 2:26 PM
Tiny
RICKCINVA
  • MEMBER
With eec relay out.16 and 37 tested hot.57 and 361 were dead. Eec relay in 16 and 37 tested hot.57 tested dead.361 tested hot. On the fuel pump relay out.381 or red tested hot.37 tested hot.926 and 238 tested dead. With the relay in 926 and 238 still tested dead. Ignition switch was in run position during all tests. All fuses check good. Thanks
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Thursday, September 30th, 2010 AT 2:42 PM
Tiny
WRENCHTECH
  • EXPERT
OK, you have to remember that the fuel pump relay only powers for 2 seconds when the key is turned on so that's the only time you can test for power out.

If you still don't see power at 238 during the first 2 seconds, then with the key on, apply ground to 926 and see if it powers then.
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Thursday, September 30th, 2010 AT 3:00 PM
Tiny
RICKCINVA
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On 238 I still dont have a 2 second light but when I grounded 926 I got a constant light on 238
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Thursday, September 30th, 2010 AT 3:46 PM
Tiny
WRENCHTECH
  • EXPERT
OK, your computer is not turning the relay on for the fuel pump. Check all your fuses first and then you'll have to test all the power and ground feeds to the computer. It may have a bad one.
You might want to find that 926 wire at the computer and ground it there just to make sure it's not broken along the way.
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Thursday, September 30th, 2010 AT 3:52 PM
Tiny
RICKCINVA
  • MEMBER
So I need to unpug the computer and check the harness wires that way or do I have to pierce the wires. Is there some where I can go to get info on which ones are hots and grounds. Thanks
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Thursday, September 30th, 2010 AT 4:01 PM
Tiny
WRENCHTECH
  • EXPERT
You can unplug it to check the power and ground supplies. I usually use a bed of nails type clip but you can also backprobe the plug with a long pin.
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Thursday, September 30th, 2010 AT 5:01 PM
Tiny
RICKCINVA
  • MEMBER
Thanks
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Thursday, September 30th, 2010 AT 5:03 PM
Tiny
RICKCINVA
  • MEMBER
First of all thanks Wrenchtech for all your great help! When I pulled the wiring harness off the computer I got that all too familiar smell of burnt electronics! I removed the computer opened the case and found 2 burnt spots on the circuit board(1 on top 1 on bottom). Im just wondering now if it was a computer isolated failure or some outside source caused it? Going to check the hots and grounds on the harness today. If you know of anything else to check please let me know! THANKS again!
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Friday, October 1st, 2010 AT 7:13 AM
Tiny
WRENCHTECH
  • EXPERT
Checking the hots and grounds was a process of elimination to condemn the computer. If you have already done that, then the testing isn't necessary. Your right that something could have burned it out but it's going to be real difficult to determine what. It may have just been a failure internally. That circuit is just a trigger ground so if it's overloaded, the worst that happens is the quad driver transistor burns out. That doesn't sound like what happened to you.
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Friday, October 1st, 2010 AT 7:33 AM
Tiny
RICKCINVA
  • MEMBER
Thanks for all the great feedback I'm ordering the computer today
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Friday, October 1st, 2010 AT 9:47 AM
Tiny
WRENCHTECH
  • EXPERT
OK,

I'd appreciate it if you posted the results when your done and left positive feedback for me.
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Friday, October 1st, 2010 AT 9:55 AM
Tiny
RICKCINVA
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I sure will. Computer should be here tomorrow
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Sunday, October 3rd, 2010 AT 9:24 PM

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