Hi, I am working on a 2005 GMC Duramax cab & chassis and was wondering if there is a way tell if the fuel tanks are balancing correctly? fuel level sensor is at 63%, front tank is at 1.88 volts and the rear tank is at 1.63 volts and I would think the pump would be running to balance it out but it is not. If I lift the front sending unit a couple of inches out of the front tank then the pump kicks in and transfers fuel. to me it seems like it's waiting to long to balance out the tanks. could the level sensors be out of calibration? What are your thoughts? Any help would be greatly appreciated. Thanks Dave
Fuel tank balance
- Thread starter dcowboydave
- Start date
Moved to fuel
Two notes regarding this. One, the fuel gauge is weighted or averaged. Two, the transfer pump doesn't run to keep the takes equal, the engine only draws from the front tank. So, it wouldn't make sense to keep both tanks at the same level.
If I remember correctly, it's something like when the front tank gets less then 50% the transfer pump will pump fuel from the rear tank until it's above X amount. Then turns off. Your test with lifting the sensor seems to indicate that it's working correctly
Two notes regarding this. One, the fuel gauge is weighted or averaged. Two, the transfer pump doesn't run to keep the takes equal, the engine only draws from the front tank. So, it wouldn't make sense to keep both tanks at the same level.
If I remember correctly, it's something like when the front tank gets less then 50% the transfer pump will pump fuel from the rear tank until it's above X amount. Then turns off. Your test with lifting the sensor seems to indicate that it's working correctly
Basing this off my Kodiak. First, you always want more fuel in the front tank than the rear. Always fill it up first. My fuel gauge always hovered around 3/4 full when fuel was being transferred. So I believe that’s when it starts the process. 3/4 is also the fullest only filling the front tank would show. I also think not all trucks work the same. Always seems a lot of people say the transfer doesn’t start till 1/2-1/4 full.
Bingo, it won't keep them at the same level. It only pulls from the rear tank when below it's threshold and stops below 100% full as well.