Gas gauge and tank switch.

[MSL]

Im not sure if this was asked but when i put gas in either tank like lets say if i put 10 bucks in the passenger side tank and fill the drivers side after and i have the switch on either tank after awhile it will say the passenger side tank is full and the drivers side is or only has the 10 bucks in it. So does anyone have this problem or know what i need to do to fix it.
?????

[old Rusty C10]

i had that problem with my old ford f 250 that has a side and rear tank what was happeneing was the side tank was allowing fuel to fall into it due to a bd in tank fuel pump dont know if that helps you or not

[MSL]

well it has a mechanical fuel pump and i changed that not to long ago this was going on since i bought the truck before i changed the fuel pump.

[77bowtie]

Look I have to ask a dumb question! Are you sure you don't have the switch wired bacwards? I read your post as though you are reading the drivers side with the switch set to the pass side. Just wondering??

[MSL]

I have never touched it the switch has always been this way but no when i put gas in the tank being the right hand tank it will read full if it s full but after awhile the gauge goes down and if you switch it over to the other tank it show the fuel is in there when its not.

[79BIG10]

Fuel switch king to the rescue

Someone has installed the switch upside down. Take the cover off by removing the ashtray completely including the cover and take off the two nuts holding the cover in. Then the switch will come out and flip it. You can't switch up the wiring since the plug will only go one way. Then place switch back in correct way and tighten back up cover.

[MSL]

Ok i will do that and let you know how it goes thanks for the info.

[dacanuck]

I think what he's saying is initially the gauges will read correctly but after awhile the readings will seem to reverse. Maybe the fuel valve/switch in the fuel lines is allowing fuel to leak between the tanks.

[MSL]

Ya i did the switch thing and it still is doing it so i think it is allowing fuel to leak through so how do i find out if that is the problem.

Thanks

[79BIG10]

Look under the truck where the cab and truck meet. I'm wondering if the PO instead of replacing the fuel tank valve spliced the two together then it's pulling from both tanks instead of just one but still showing the readings of both tanks since they're not tied into that for the level of the fuel in the tank..

[77 Shortbed]

Does it do this after driving it for a while or just while setting? Do you have the valve that has 6 ports or 3? (The 6 port has a return line for each tank.) Does your truck have a return line to the valve from the fuel pump? Does your problem work the other way too? (Filling the driver's side and $10 in the passenger.)

I'm not sure how the 3 port valve works but the 6 port valve sends the overflow back to the tank that the valve is switched to. If you are running off the passenger tank all the extra gas the fuel pump pumps returns to the passenger tank. Same goes for the driver side. If you have the 6 port valve it is possible that the return lines for the tanks are reversed.

[MSL]

i will check to see if its spliced.
It does do it after driving. i am not sure what the valve is since i havent been under the truck to look yet. and the problems works both ways.

[77 Shortbed]

Look on the passengers side near the rear of the cab. It is mounted to the frame rail on the inside. It should have fuel lines from both tanks attached to it. If it is the 6 port valve there will be return lines to each tank also. My guess is that those return lines are reversed.