Hey guys hope all are doing well and happy new year!

For some odd reason my fuel keeps going from one tank to another, front to rear and rear to the front making hard to drive and find out how much fuel I have or used in a specific run what could is the reason for this problem too high of pressure bad pressure regulator?)


Thanks for the advice

Andre

 

On each of the fuel pump assemblies there is a valve that is supposed to open the return line to the tank whenever that particular pump is on and running. When the pumps get old, the valve sticks in the open position, allowing fuel not used by the engine to return to the wrong tank via the stuck valve. So if pump A is running, the fuel should return to that tank because the valve is open. But if pump A's valve is stuck, fuel will return to both tanks when pump B is running. Since you have the problem of fuel transferring to both the tanks, you have both valves bad and need to replace both pumps.

However, there is one other thing that can cause this symptom. On the discharge of each pump there is a check valve that allows fuel to only flow towards the engine. If this valve is bad, it will allow fuel to backflow through the pump when the pump is off and the other one is running, resulting in the tank fill in with fuel from the other tank. This problem was the cause of a recall in the 1990s where we had to install a check valve on the outlet of the pump as a backup to the in-tank unit. You may be able to track down some of these check valves and install them yourself, as they may be cheaper than replacing the pumps (although the pressure-side check valve may not be your problem, in which case the recall parts will not cure your problem.)

Jay

 

What year truck are we talking about here?