89 F350 7.5L Fuel System Electrical Issues


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Old 12-13-13, 06:38 AM
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89 F350 7.5L Fuel System Electrical Issues

1989 Ford F350 Crew Dually
7.5L Gas / Automatic (C6)
117K miles
In Rail Fuel Pump & (2) in tank Pumps (F & R)

Truck sat for years, but has been started and run weekly for past year or so. Fuel in tanks went bad, added berrymans and 5 gallons each at empty, ran that out and repeated. Truck would always start (although ran roughly bad fuel...could smell varnish). About a month ago the starter solenoid stuck and had to be replaced. Did so, re-charged battery, and simply turns over with no start. Fuel gauges to this point had always ready correctly. After solenoid replacement, trying too start, the gauges read pegged at full side, and no start.

Testing to this point.
Spark at distributor
voltage correct
all yellow wires at solenoid good
power supplies at eec and FP relay good
power good on both sides of inertia switch
power good at supply on tank switch
can hear primary in rail pump operating 2-3 sec and off
same on power at tank switch

Only item(s) touched is the relay replacement and jumper cables at battery.
I have spent week or better researching this issue and all I am able to locate is concerning the in rail pump. My problem is that I don't believe the in tank pumps are activating which seems to be a ground or lack of issue...

How can I check the eec for proper ground circuit or could it be the actual eec causing the issue?

Any and All help would be greatly appreciated...
 
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Old 12-14-13, 01:50 PM
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Ground circuit

How about any idea on how to test ground circuit for the pumps and senders. Trying to not remove the tanks if at all possible.
Thanks again.
 
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Old 12-14-13, 01:56 PM
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Welcome to the forums.

I had an 89 E-350 with the same setup. Same dual tanks and engine size.

The pumps are fairly noisy.... did you try to hear if either one came on when is turned on ?
They'll only run for 10 seconds if they're working.

I had several problems with mine as they got older. Bad intank pumps and trouble with the pump relays under the hood on the drivers side.

I had all the service manuals here for it but have since given them away.
I believe there is a three wire connection to each tank. They are switched thru the tank selector switch. I'll see if I can locate a wiring diagram.
 
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Old 12-15-13, 09:29 AM
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Diagrams

I appreciate the response. I have every manual known to ford and man for that matter. Full set of ford dealer service manuals. It's that everything I find and read keep pointing me back to a ground issue. I am going to go ahead replace the solenoids just because. Thing is everything worked fine up to the point the starter solenoid stuck and got replaced. Then gauges started reading at full peg...way past full and truck wouldn't start from that point. Gotta be related somehow. Doesn't EEC cut ground to pumps to shut them off? Also do you know if the pf relay runs all pumps or just in tank pumps?
Thanks again
 
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Old 12-15-13, 09:57 AM
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The EEC may cut ground to a relay that cuts power to the fuel pumps but ground is not removed from the fuel pumps for shutdown.
 
 

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