fuel tank switch
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fuel tank switch
Does anyone know how the fuel tanks switch works?? I switch from the front to the rear tank and the gauge doesn't move, and I know that there is less fuel in the rear tank. Does this mean that the in tank pump and sending unit work together? It worked fine before I did a motor swap, and now doesn't???
Bob
Bob
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From: Liverpool, NY
I know on my 88 F150 I had it was all operated on Vacuum and when I dropped the saddle tank, the pump and sending unit were together. Of course mine was all lacquered over from who knows what. You'll want to check your connections on the tanks as I found out, the slightest movement or bump will whort the connector out and read 0 no matter if you switch from one tank to the other.
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I hav ean 85 f150 with aa 5.0 fuel injected, one low pressure pump in each tank and on high prressure on frame rail. I was wondering if the pump and sending unit for the ffuel level guage is the same? The front tank works fine, when I switch to teh rear it does nothing, the guage does not move. So I assume that it is no switching to the rear tank, but remaining on the front. I did remove the inertia switch when I swapped motor, if that makes a difference. I jusst do not want to drop the tank before knowing that it needs a pump and or fuel guage sending unit?
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They should be the same in both tanks. Are you getting gas from the rear at all? It could just be the float's busted. If you're not even getting that then I'd take a look at the harness since they like to oxidize where the harness meets the inside pump at the top of the tank.
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I cannnot tell if I am getting gas from the rear. when I switch the fuel tank selector switch the guage remains the same, if it says half or full it will not move. Are the in tank pumps and the guage from that tank on the same circut?? Or could it just be the float? And if it is the float how do I tell, remove a fuel line and see if its pumping?
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if while youre driving and you switch to the rear, if the truck chokes, no gas is being pumped through the line and the problem lies with the sending unit. Ford wired both sending units and exterior pumps to the same line/same gauge with the switch as the break.
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I've got the same problem with my 85 f150. Except I can switch between tanks and there is no problem. Only thing is when I switch to my back tank the gauge drops to empty.
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Brett Foote
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I have gas coming from the rear tank. All it does is drop to empty on the gauge. I have a feeling that its the sending unit, I just haven't gotten the time to get up under there and pull it yet to see if that's the problem or not. I've heard that in order to test them you pull them and check the resistance while moving the float upward to simulate gas in the tank.
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yeah, there is the possibility the sensor the float activates is malfunctioning. Sadly you have to drop the rear tank and replace the entire sending unit. I ended up going through this when I had my 88 f150 with the front tank. I was reading levels but no go on the gas. Dropped the tank and whole thing was laquored over like someone dumped a gallon of varnish into the tank. What caused the lovely no gas issue was the screen was clogged. I take that back, it was covered in laquor lol. Bobs problem is either the sending unit itself or something in the wiring since they do like to corrode and not work. My first guess would have been the switching solenoid in the switch pump but Ford didn't start doing away with vacuum assist until 1989.
Hope this helps guys.
Hope this helps guys.
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I'm having a similar problem with my truck now too. When I try to switch from one tank to another it seems like the truck is still getting fuel but my gas gauge shows totally full instead of showing empty. I can flip from front to rear tank and nothing seems to happen. The gas gauge doesn't move at all though, just stays pegged at completely full. What's the problem and how do I fix it?
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