Bad fuel leak, this thing's a ghost!!!

R

rockytopcummins

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Jul 27, 2008
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This one has got me stumped and I need some help. No injector lines are leaking, everything on top of the pump is dry, no holes in the fuel line or return. Yet sometimes when I get out of the truck there seems to be fuel pouring from the hog's head on the front axle that will then slow to a very slow drip. It only leaks bad when the truck has been driven and there's not even a drip on a cold start. This leads me to believe that whatever is leaking only presents itself when the FP increases while I'm driving. I've tried holding the throttle at about 2k but this will not replicate the symptoms described. I don't know where else the fuel could be coming from. I've been all up under with flashlights and what not but like I said, it's like once the engine comes back to an idle the d@mn leak vanishes. I really hope somebody can help with this.
 
On my 24v one injector line going into the head was leaking slow. hard to find the fuel was running along the intake plate and off the end of the head I just loosened the nut on the line and retighten fixed the problem maybe something to look at if you didnt already
 
Return line on the back of the head?

Have you pressurized the fuel tank with air and checked for leaks that way?
 
I hadn't thought of pressurizing the fuel tank, that's not a bad idea. I checked the return line. Like I said before, all injector lines are dry at the head and at the pump. Head is dry. I just don't understand where it could be coming from because the fuel is running from somewhere onto the front axle and then the ground. By the time I can stop the truck, get out and get under it with a light, the leak has stopped except for residual drips. It's about to drive me nuts!!!!
 
rockytopcummins said:
I hadn't thought of pressurizing the fuel tank, that's not a bad idea. I checked the return line. Like I said before, all injector lines are dry at the head and at the pump. Head is dry. I just don't understand where it could be coming from because the fuel is running from somewhere onto the front axle and then the ground. By the time I can stop the truck, get out and get under it with a light, the leak has stopped except for residual drips. It's about to drive me nuts!!!!
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Are you utilizing your stock fuel filter housing? Your fuel filter housing is above the diff if you still have it.
 
Is there anything on the very front of the pump between the timing case and the pump itself that could leak? That's my last guess. After that.....I just don't know!!!
 
how did you do your return line off the pump? is it part of the steel line with a rubber hose clamped on it?

does your AD shut off when you shut the truck off? might have a leak there if it still pushes fuel after the engine is off or its just bleeding off pressure after you shut the truck off.

if its hitting the axle my guess would be either the return fitting off the injection pump or if you clamped a rubber hose on the steel it might be leaking.
 
When I did mine, I ran AN fittings from the pump return all the way back with braided AN -6. I used an AN fitting from the head to the pump return and tied it all in with another AN fitting "T". Using the AN fittings was more expensive, but made it real easy to eliminate fuel leaks.
 
Chevycummins said:
how did you do your return line off the pump? is it part of the steel line with a rubber hose clamped on it?

does your AD shut off when you shut the truck off? might have a leak there if it still pushes fuel after the engine is off or its just bleeding off pressure after you shut the truck off.

if its hitting the axle my guess would be either the return fitting off the injection pump or if you clamped a rubber hose on the steel it might be leaking.
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I'll have to check that return line again, because what you described is how mine's set up. The AD does shut off when the key is off.
 
To add to the mystery, the fuel leak has magically stopped before I could even figure it out. This thing's weird as hell!
 
Mighty be a crack in a line and with you moving things around to check might of positioned it just right to stop leaking now
 
I think you have a crack in a line and it could be spraying to the front of the engine. I would be checking the llines coming off of your lift pump for cracks.
 
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