Dual Gastank Problem with switch-over
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Dual Gastank Problem with switch-over
Hi All,
My 86 F-150 has dual gas tanks and the front one works ok but when I switch to the rear tank the gas guage plunges to E and it keeps running off the front tank. It use to switch over to the rear tank because the truck would start skipping an running weird because the gas in the rear tank is gotta be over 3 years old by now. What do I need to check or replace to be able to get my rear tank back working?
Thanks
Alan
My 86 F-150 has dual gas tanks and the front one works ok but when I switch to the rear tank the gas guage plunges to E and it keeps running off the front tank. It use to switch over to the rear tank because the truck would start skipping an running weird because the gas in the rear tank is gotta be over 3 years old by now. What do I need to check or replace to be able to get my rear tank back working?
Thanks
Alan
Elder User
Joined: May 2004
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From: Edwards Air Force Base
The in tank low pressure fuel pump is likely dead or the little hose that connects it to the whole assembly has a hole in it. Either way, you need to drop the tank and take the assembly out.
The tanks switch by the switch on the dash turning on the appropriate low pressure in tank pump, the pressure of the fuel in that line pushes the solenoid on the frame to swivel to feed that tank to the high pressure pump, through the filter and onward to the engine. If the tank pump isn't working, then there won't be enough pressure to make the solenoid swing into the right position.
You can either drop the tank or lift the bed off and get to it that way.
Good Luck,
Lee
The tanks switch by the switch on the dash turning on the appropriate low pressure in tank pump, the pressure of the fuel in that line pushes the solenoid on the frame to swivel to feed that tank to the high pressure pump, through the filter and onward to the engine. If the tank pump isn't working, then there won't be enough pressure to make the solenoid swing into the right position.
You can either drop the tank or lift the bed off and get to it that way.
Good Luck,
Lee
Junior User
Joined: Jun 2006
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I'm having a similiar issue with my 85 F-150. It has dual tanks and I switched it from EFI to carb.
I removed the in-tank low pressure pumps so that only the engine mounted mechanical pump would do the job. It only seems to run off of the front tank. I'm pretty sure older carbureted F-150's with dual tanks didn't have the in-tank fuel pumps... Can I take a fuel line solenoid from one of those trucks?
Thanks,
Sal
I removed the in-tank low pressure pumps so that only the engine mounted mechanical pump would do the job. It only seems to run off of the front tank. I'm pretty sure older carbureted F-150's with dual tanks didn't have the in-tank fuel pumps... Can I take a fuel line solenoid from one of those trucks?
Thanks,
Sal
Post Fiend
Joined: Jul 2004
Posts: 8,786
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From: Northern California
Originally Posted by ssanto
...I'm pretty sure older carbureted F-150's with dual tanks didn't have the in-tank fuel pumps... Can I take a fuel line solenoid from one of those trucks?
You will need to swap it out for one that goes with the mechanical pump carb system. The most common was the three line solenoid. Two fuel inputs and one output to engine. Solonoid Energised (12V) is for one tank, and no power (0V) is for the other tank. It grounds to the frame rail.
You will have to do some moderate wiring, shouldn't be hard.
Hope this helps.
New User
Joined: Mar 2006
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Ok, along the same lines, but different..... Everything is great with mine switched to the front tank, guage works, runs fine, etc. However, when I switch to the aft tank, the guage goes past E and stays there, but it is running fine and using the fuel in the aft tank. Is this a problematic problem with the switch or the sending unit? 1985, F250, standard cab, AOD, 302, 4X4.
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Post Fiend
Joined: Jul 2004
Posts: 8,786
Likes: 28
From: Northern California
most likely it's the sending unit.
Although it could be the wiring to the aft sending unit too.
But I would lean toward getting a new sending unit. Very common problem with the 1980 to 1986.
Ground out the sending unit wire breifly with someone watching the gas gauge etc.. It will move toward full if the wiring is good. dont ground it for too long, it can damage the gauge.
hope this helps.
Although it could be the wiring to the aft sending unit too.
But I would lean toward getting a new sending unit. Very common problem with the 1980 to 1986.
Ground out the sending unit wire breifly with someone watching the gas gauge etc.. It will move toward full if the wiring is good. dont ground it for too long, it can damage the gauge.
hope this helps.
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