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Rear fuel pump dead on 91 F250, cant figure out why

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  #31  
Old 07-24-2014, 07:48 PM
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I take it you are saying that you grounded pin #6 of the self-test plug with the key on and the fuel pumps did not run.

If that is so did the fuel pump relay click when you grounded pin #6?

If not did the EEC Power relay click when the key was turn to run?

If the EEC Power relay did click when the key was turn to run did the red wire going to all the fuel injectors have power on them and light a test light?

If the fuel pump relay did click when you grounded pin #6 and the fuel pumps did not run then you either have a bad fuse link at the starter solenoid on the fender and no power on the yellow wire feeding the fuel pump relay or you have a tripped fuel shutoff switch or a bad selector switch at the dash or bad wiring to the pumps or of course bad pumps.
 
  #32  
Old 07-24-2014, 08:06 PM
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Originally Posted by subford
I take it you are saying that you grounded pin #6 of the self-test plug with the key on and the fuel pumps did not run.

If that is so did the fuel pump relay click when you grounded pin #6?

If not did the EEC Power relay click when the key was turn to run?

If the EEC Power relay did click when the key was turn to run did the red wire going to all the fuel injectors have power on them and light a test light?

If the fuel pump relay did click when you grounded pin #6 and the fuel pumps did not run then you either have a bad fuse link at the starter solenoid on the fender and no power on the yellow wire feeding the fuel pump relay or you have a tripped fuel shutoff switch or a bad selector switch at the dash or bad wiring to the pumps or of course bad pumps.

Relay clicks when key is on.. Yellow wire has power on relay no burned links..red wires on injectors have power.. Inertia switch good.. Can you bypass fuel selector switch in dash? No power to either pumps..
 
  #33  
Old 07-24-2014, 09:39 PM
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The frame pumps power does not go through the fuel selector switch in dash so if it does not have power then it is not the fuel selector switch in dash.

Have you tried resetting the fuel shutoff switch?
Have you checked for power at the fuel shutoff switch with the key on and pin #6 grounded of the self-test plug?
 
  #34  
Old 07-25-2014, 12:03 PM
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Originally Posted by subford
The frame pumps power does not go through the fuel selector switch in dash so if it does not have power then it is not the fuel selector switch in dash.

Have you tried resetting the fuel shutoff switch?
Have you checked for power at the fuel shutoff switch with the key on and pin #6 grounded of the self-test plug?
Grounded pin 6. No voltage to fuel shut off switch.. Thanks for your help and Patience.. What would come next?
 
  #35  
Old 07-25-2014, 12:43 PM
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Originally Posted by cagedog
Grounded pin 6. No voltage to fuel shut off switch.. Thanks for your help and Patience.. What would come next?
Also... I got under the truck and there is voltage to high pressure pump and voltage at yellow wire to fuel tank.. But to power at shut off switch? Doesn't make much sense to me...any help.is appreciated
 
  #36  
Old 07-25-2014, 01:37 PM
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Update...spent about 1 hour with my test light.. Something changed..was getting power at yellow ..wht with green strip and red on relay...now only yellow is hot...also when I tested earlier I had power to fuel injectors... Now I don't.. Grounding pin 6 makes relay click but no pumps Also check engine light that is normally on while key is in on position.. Is no longer on.. While fumbling with relay...I did get fuel pumps to flicker on for a brief second.. Current situation.. Power at fuel pumps..but not turning on... No power to injectors.. Relays only have power at one wire each...yellow on one relay...black w yellow stripe on other. What am I missing?
 
  #37  
Old 07-25-2014, 06:06 PM
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If the fuel pump relay clicks when you ground pin #6 with the key on then you should also have power to the fuel injectors, it is the same red wire circuit coming from the EEC Power relay.

Also if you have power to the high pressure pump on the frame then you would also have power at the fuel shut-off switch.
 
  #38  
Old 07-25-2014, 07:48 PM
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Ended up being a connection on the relay.. Blue wire that splits into 2 red wires by fusable link on the plug.. Still no power at fuel cut off switch.. My best guess is it was bypassed at some point.. Everything seems to be working again...for now...thank you!
 
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