Gas Problem! Help
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From: Mobile, ALABAMA
Gas Problem! Help
I need some help on this one...<1990 F-150> 5.0...got dual tanks..But some of the gas from the front tank makes its way to the rear tank (which doesnt work)...Which is making my gas mileage horrible!...I need to know if anyone has had this prob with their F, and if so what is it? thx guys
nd4spd
nd4spd
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From: Mobile, ALABAMA
well if the truck burns the same amount of gas, then i guess im just loosing it in the other tank. I just 'think' my gas mileage it bad, when in reality, some of its just moving to the back tank? my rear tank fuel pump is bad...and i have a FULL TANK back there....Ill have to check up on that recall, thx Andym
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From: DeKalb, IL
Chance are your fuel tank selector switch has gone out. I had the same problem on my 88 F150. What happened was that the selector valve located in the frame rail would not fully switch from the front tank to the rear tank and vice versa. The truck would then pull fuel from one tank and instead of the return fuel going back to the same tank it would flow to the other tank. I really noticed it easy because one of the tanks was overflowing. The valve is not hard to replace. That is just my opinion. Good luck on the fix.
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Well thats good thats its on the frame rail, with my luck it would be inside one of the tanks...I have the same prob before, with fuel spilling out of the rear tank when i open the gas cap....How much did the valve cost you, can you get it at an auto parts store or is it a dealership part only....I'm just trying to get a good idea of what im dealing with before i go replacing parts... But I do believe your right, thx for your help Metallicafan
Originally Posted by MetallicaFan39
Chance are your fuel tank selector switch has gone out. I had the same problem on my 88 F150. What happened was that the selector valve located in the frame rail would not fully switch from the front tank to the rear tank and vice versa. The truck would then pull fuel from one tank and instead of the return fuel going back to the same tank it would flow to the other tank. I really noticed it easy because one of the tanks was overflowing. The valve is not hard to replace. That is just my opinion. Good luck on the fix.
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From: DeKalb, IL
No problem man. As many people that have helped me on this site this is the least that I can do as to try as help others. Good luck with it.
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Do the fuel injected trucks use selector valves? I thought they just had electric fuel pumps in the tank that got powered when you switched the tank switch. Thats how my 86 302 EFI is. I know the diesel trucks and carburated trucks had selector valves.
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Don't recall ever seeing or knowing of a selector valve on my '90 EFI, but I did have that recall done several years ago. I think the dealer installed a check valve(s) in the system to prevent the fuel from going to the other tank. The recall should be free if that's what it turns out to be. The dealer should be able to run your VIN number and see if it needs to be done.
Last edited by guzzler96; Jun 10, 2004 at 07:53 PM. Reason: spelling
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From: DeKalb, IL
Yeah, the gas models have selector valves too. It is located in the frame rail on the driver side of the truck. The valve is located behind the fuel filter in the rail. Mine went bad and I had to change it out. I had the problem of the fuel being sucked from one tank and the return being pushed into the other tank. The new valve did the trick. Works like a champ now.
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I understand that it is on EFI models. My truck is an 88 F150 5.0. You may want to call it a diverter valve but that is what actually closes off on tank while using another. I do not think that there were any actual wires going to it. I think that it is a mechanical unit that switches from one tank to the other. The way that I understood how it works is that when one of the low pressure pumps in the tank switch off and the other switches on the differences in pressure activate the valve in the diverter valve. That is what caused my problem of the one tank being drawn from and the return fuel going to the opposite tank. The more that I think about it the more that I think that may not be the problem here. In 1990 Ford went to the high pressure pumps in both tanks and did away with the valve in the line. They had all that built in to the pump assemblies in the tank.
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Metallica, I think your right....I know I have the fuel pump and the pump assemblies all in the tank...which sucks if you need to change something out if its bad. I havent looked under it yet (because its been raining) But from past visits under the truck, I dont recall seeing a selector valve(divertor valve) I believe its in the tank....I think my solution will just have to be a water hose and my mouth 
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When you said selector valve, I thought you meant the set-up like on carburated and diesel trucks. They use a electric solinoid to change the flow of the fuel. Your right, the later model trucks must have the high pressure pumps and check valves in the tanks because they dont have the diverter valve located in the frame rail. Really, all the diverter valve is, is a check valve, to prevent gas from flowing back into the tank. Even the trucks with single tanks have these valves.
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So what your saying is that I would have to open up my tank and replace the diverter valve? Sounds like a pain 
Originally Posted by fai4g63
When you said selector valve, I thought you meant the set-up like on carburated and diesel trucks. They use a electric solinoid to change the flow of the fuel. Your right, the later model trucks must have the high pressure pumps and check valves in the tanks because they dont have the diverter valve located in the frame rail. Really, all the diverter valve is, is a check valve, to prevent gas from flowing back into the tank. Even the trucks with single tanks have these valves.