3500 fuel problems

alsride · November 20, 2003

I have a 1996 3500 with a 6.5 turbo diesel. It is a flatbed with a dual fuel tank setup. Each tank has a pump. The rear tank pumps into the front tank and the front tank pumps up to the motor. I am pretty sure it is a factory setup, both tanks drain equally. I can drive the truck all day sometimes with out a problem, but most of the time I will be driving and the thing will stall out. I know it's a fuel supply problem. I turn the key on and I can hear the fuel pump come and about a second later it shuts off once it builds up pressure. The truck will immediately start up and run until it stalls out. It already has a new fuel pump and it's not sucking air. I already replaced fuel filter and still has problem. I figure it is either a problem with the fuel pump relay(highly doubt with this case) or a tempermental pressure regulator. I did not find a return fuel line so I supposed that the computer monitors fuel system pressure and turns on pump when it needs pressure. I figure if the pressure sensor isn't working right it doesn't turn the pump on, until I turn the key on again and it turns on pump because of default. If anyone has any knowledge or info on this problem it would be greatly appreciated. Thanks.

RonJ · November 20, 2003

ALSRIDE, I had the same problem with my '96 3500HD(2 tanks) 6.5TD The 1st dealer didn't find the problem. everything tested ok. It ran ok for a while , stalled, I took it to another dealer. There they replaced the "fuel lift pump" Its located on the chassis under the drivers seat The mechanic said that although you could hear the pump running It didn't maintain the correct pressure. Problem solved for about 20,000 miles. Then I was left straned again. I installed another pump, worked great for 2 weeks, stalled again. I didn't do anything and the truck has been running good for a couple of months now.

This truck has always been a PIA. loosing power, smoking when towing, displaying service engine soon light , not saving codes for the dealer. finally discovered it needed a 1) boost sensor-16009886, 2) vacuum pump12562793, 3) waste gate selnoid-1997227 finally ran good. It still rocks and smokes at the first start up of the day.

My '98 k3500(one tank) 6.5TD. stalled on me twice. I replaced the same pump ran great then stalled twice on its new owner, but not again on him in 20,000 miles.