Fuel pump issue
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New User
Joined: Dec 2013
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From: Northeast Pa
Fuel pump issue
I'm new to this forum so please be gentle. I have a 1989 F250 w/ 351 5-speed 4x4. Parts that have been replaced: both fuel tanks and pumps, in line fuel pump, fuel filter, distributor (long story), battery and alternator. The problem I'm having is the low pressure fuel pumps aren't working. They did work after installation, but now nothing. I've grounded #6 and the in line pump would run but not the low pressure pumps. I then ran a jump wire between #2 and #6 and the same thing only the in line pump would work. Any suggests were to look next? I also had a problem with the rear tank pumping fuel into the front tank before the pumps stopped working. I know the is the mechanical switching valve, which is waiting to be put in.
Freshman User
Joined: Nov 2013
Posts: 32
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From: western MA
I'm new to this forum so please be gentle. I have a 1989 F250 w/ 351 5-speed 4x4. Parts that have been replaced: both fuel tanks and pumps, in line fuel pump, fuel filter, distributor (long story), battery and alternator. The problem I'm having is the low pressure fuel pumps aren't working. They did work after installation, but now nothing. I've grounded #6 and the in line pump would run but not the low pressure pumps. I then ran a jump wire between #2 and #6 and the same thing only the in line pump would work. Any suggests were to look next? I also had a problem with the rear tank pumping fuel into the front tank before the pumps stopped working. I know the is the mechanical switching valve, which is waiting to be put in.
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New User
Joined: Dec 2013
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From: Northeast Pa
Not sure on the pressure at the rail, I'll be getting a pressure gauge soon to check that. If you mean corroded battery terminals no as it has a new battery and all fuel pumps have been replaced. The only place I didn't check is the starter. Not sure where the check valve is located between the tanks.
Lead Driver
Joined: Aug 2006
Posts: 5,670
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From: Sand Lake, MI
Edit, +1 on the select switch.
Fuel tank select switch, power to high pressure pump is direct from the inertia switch power to high pressure pump doesn't pass through it, it runs regardless tank selected.
I'd start by checking it, perhaps had it unplugged for some reason forgot to plug it back in?
Fuel tank select switch, power to high pressure pump is direct from the inertia switch power to high pressure pump doesn't pass through it, it runs regardless tank selected.
I'd start by checking it, perhaps had it unplugged for some reason forgot to plug it back in?
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New User
Joined: Dec 2013
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From: Northeast Pa
I recall reading a post on how to test the switch. For $15 I think I'll try the switch. Could it possible be a bad ground some where?
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Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
The high pressure pump, the boost pumps in the tanks and the fuel senders in the tanks all use the same ground point.
So if the high pressure pump runs the ground should be good.
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So if the high pressure pump runs the ground should be good.
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New User
Joined: Dec 2013
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From: Northeast Pa
I have searched all the local auto part stores and no one even lists a fuel selector switch for an "89 F250. The only one I found was for a '92-'96. With some modifications I can make it work but my only concern is, do the pins match the '89? Example: is the power pin on the '89 plug in the same location as the '92-'96 and so on?
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New User
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From: Northeast Pa
Correct me if I'm wrong about the following:
'96 plug pins
1- Sending unit rear tank
2- Fuel gauge
3- Sending unit front tank
4- Power rear tank
5- Inertia switch
6- Power front tank
'89 plug pins
1- Power rear tank
2- Inertia switch
3- Power front tank
4- Sending unit front tank
5- Fuel gauge
6- Sending unit rear tank
'96 plug pins
1- Sending unit rear tank
2- Fuel gauge
3- Sending unit front tank
4- Power rear tank
5- Inertia switch
6- Power front tank
'89 plug pins
1- Power rear tank
2- Inertia switch
3- Power front tank
4- Sending unit front tank
5- Fuel gauge
6- Sending unit rear tank
Thread Starter
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New User
Joined: Dec 2013
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From: Northeast Pa
OK, the switch I have is for a 92-96. All the local auto parts stores don't even list a switch for the 89. I was able to modify the switch so the plug will work, I just wanted to make sure the wiring was the same for each switch.
