I have a 2005 HD with a 6.6 LLY. I had an auxilary fuel tank installed with plumbing that allows me to swap to either tank. I also had inline fuel pumps installed on both tanks that boosts the fuel pressure to the injector pump. Everything has worked great for several years now. However within the last year I have been having major fuel leak problems. When the problem occurs, the leak is severe, but the engine runs fine.

The first time it happened the Chevy folks said it was a hose clamp on the return line coming from the injector pump back to the fuel tank. The same thing happened again about 6 months later. The Chevy folks replaced the injector pump, replaced both fuel line hoses and installed heavy duty hose clamps. Now it has happened again and what's weird is that the leak stops when I turn the in-line fuel pumps off. The fuel pumps only generate about 8 psi. The Chevy service folks are now baffled. The truck runs fine without the inline fuel pumps but I can believe that such a small pressure increase causes such severe fuel leaks.

Does anyone have any other suggestions short of taking my inline fuel pumps off???

Does anyone have any other suggestions short of taking my inline fuel pumps off???


Yup... but first... when you say "leaks"... do you mean you actually see diesel hit the ground? If so... where? That will help us narrow down the problem.

The leak is coming from somewhere on top of the engine (but the leak is not visable) and drips from the back of the engine. It filled the floor of my garage this morning. All visible fuel lines are OK. Any help is appreciated!

Where is the Y connecting the two tanks? Where are the lift pumps located? You have to be more specific with the drip location. Ie : dripping off bell housing? Because it only leaks when pumps are on you can rule out anything down stream of the injection pump. I would start at the supply and return line connections located near the glowplug module (driver side).