Front tank no power
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Front tank no power
I've got a 90 F-150 302FI auto with dual tanks. I dropped the front tank because when that tank was selected the truck died, also if the selector was on the front and the key was turned on you couldn't hear the pump spool up like you can on the rear. I got a pump and sending unit from Ford and a new wiring connector to go with the new style pump. Before doing any soldering I thought I'd check the wires for power, coming off the frame harness I have RD (going to Rd on the pump), OR (going to Blk on the pump), Lt Blu w/yel (going to yel on the sending unit) and blk (ends at pump hookup, sender gnd?). When using a test light with the key on and the front tank selected I am only able to get power from the Lt blu/yel wire(pwr to sender) so far I can't get pwr to the pump. I swapped the selector switch from my 94 F-150 and it makes no difference. Is there somewhere else such as a relay or fuse that would cut off power to the front tank only? I've checked the fuse under the dash and the relay on the fender apron, still nothing.
Elder User
Joined: Feb 2006
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From: Formerly Nawlins
Doesn't sound like the problem I have .... mine doesn't get enough pressure from the front tank ... I will drop it sooner or later and hookup straight to the pump and check pressure there .... I changed the pump a few months ago. Sounds like you checked all the electrical connections ... but I could be wrong. Hopefully SubFord will jump on this in a few minutes and get you some other things to check.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
You would just have to trace the wire from the dash switch to the tank.
No there are no other switches, fuses or relays to check.
You should have the bottom relay unless someone has upgraded it.
Here is a diagram of your system.
No there are no other switches, fuses or relays to check.
You should have the bottom relay unless someone has upgraded it.
Here is a diagram of your system.
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Thanks for the diagram Sub, I was afraid I was going to have to trace the complete wire. There's no other explination other than something unplugged or worn through. There was a recall check valve added to the old pump and I put it on the new one, is it still necessary even with this new pump? The truck is bone stock with 85k miles, and in my family since 92 and I know the first owner so it's history is well accounted for by me. Thanks again for your assistance, I really appreciate it.
Tommy
90 F-150 302,swb XLT Lariat, 94 Lightning, 02 SD,PSD 4X4 CC,SWB, 76 Bronco, 89 Sleen SSC clone, 93 SC Thunderbird, 69 Mustang Conv, 70 Boss 302, 65 G.T.350 replica, 98 Ducati M900, 76 Citabria 7ECA.
Never at a loss for opportunities to work on something.
Tommy
90 F-150 302,swb XLT Lariat, 94 Lightning, 02 SD,PSD 4X4 CC,SWB, 76 Bronco, 89 Sleen SSC clone, 93 SC Thunderbird, 69 Mustang Conv, 70 Boss 302, 65 G.T.350 replica, 98 Ducati M900, 76 Citabria 7ECA.
Never at a loss for opportunities to work on something.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
Originally Posted by el jefe
There was a recall check valve added to the old pump and I put it on the new one, is it still necessary even with this new pump?
One member of the forum said they put two on his 1989 and it would not run very well at all until he removed them. The 1989 has a different fuel system altogether and the only check valve they have in inside the pump on the frame.
Last edited by subford; Jul 14, 2007 at 06:59 PM.
Elder User
Joined: Feb 2006
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From: Formerly Nawlins
I initially reinstalled the inline checkvalve on my front tank. It was added with a recall, but not knowing the original owner ... can't verify that past what I was told by a service dept person at the local dealer. I removed it when the pressure was really low and the checkvalve seemed to be very hard to blow through, but removal didn't help my pressure problem and I still can not start the truck from the tank, since it will only get to 27psi after 10 times turning the key on and off. I did not remove the one from the rear tank .... but did check to see one was there as well. After I pull the tank again and check pressure from the tank to the gauge without going through the whole fuel system ... if it check out then I will guess my problem is with a bad checkvalve on the rear tank letting pressure stay to low being output from the front tank and deal with it when I feel like it. I don't use the front tank at this time.
