How do dual fuel tanks work!

[RunMonkeyRun]

Hey there guys! I have a 99 chevy c3500 hd 6.5 with dual tanks. I ahve done searches here but did not seem to get far. The transfer pump from the rear tank is not functioning and there is no power going to it aswell, so the primary tank is the only thing working, problem is my fuel gage was not telling me the truth about how much fuel I had in the tanks so found out why I was sputtering all the way to home.

I have changed the sending unit in the primary tank ( mechanics advice) and has done nothing. Fuel gage will read just above quarter of a tank for about 10-15 seconds with the ignition on then drops to empty. Where does the transfer pump get it power from? can someone please let me know how the dual tanks fuel system works?

I think I posted this in the wrong thread before.

[RunMonkeyRun]

how does one go about testing the fuel balance module?

[RunMonkeyRun]

Any one, nobody!!!!!

[joed]

I don't have this system, but here's a description for the system from my 1998 on-line service man. subscription:


"The fuel balance control system consists of the following components:

* Front (main) fuel tank sender.
* Rear (auxiliary) fuel tank sender.
* Balance fuel pump.
* Balance fuel pump relay.
* Fuel sender and balance module.

On vehicles with dual tanks, the front tank is the main and the rear tank is the auxiliary. The main fuel pump supplies fuel to the fuel injection unit. The low pressure (about 32 kPa or 7 psi) fuel balance pump is used only to transfer fuel from the auxiliary tank to the main tank in order to balance the fuel levels in both tanks. As the main tank level drops to about 25 % below the level in the auxiliary tank, the fuel sender and balance module energizes the fuel pump relay. This pumps the fuel from the auxiliary tank to the main tank. When the level in the main tank reaches a level slightly higher than the level in the auxiliary tank, or the auxiliary tank is empty, the module de-energizes the balance pump relay and fuel pump. Any malfunction in either of the fuel gage circuits will disable the system and the fuel will not be transferred from the main fuel tank to the auxiliary fuel tank."

Hope that helps. Joe.

[RunMonkeyRun]

Thanks Joed, now atleast I know exactly how it works it is just amatter of how to trouble shoot if it is actually the module or aux. sending unit.

Thanks again

Rob