Can a mechanical fuel pump leak, not at a hose?

thecarman

Well-Known Member
Joined
Mar 17, 2005
Location
Apex, NC
I noticed fuel leaking out of my 6.2 diesel today. I thought it was the inlet hose to the mechanical (block mounted) lift pump, even though the hose itself was not wet. I tried to tighten the clamps but one stripped out. After replacing both clamps, it is still leaking, and definitely not from the hose.

This is a block mounted fuel pump just like what you'd see mounted to any carbureted V8.

The body of the pump is wet and drips of fuel continually form on it. Can the pump itself leak, not from a hose connection? I can't see where it would be coming out of the pump, but at the same time, I can't see any other place the fuel could be coming from. I can't see anything that could be leaking this fuel onto the pump. It is not coming from the hoses, it is actually on the round part of the pump *above* the hoses.

I just want to make sure before I pull the pump that it's really the pump leaking, and not something else.

I've heard of the fuel pump leaking fuel into the oil, but never the pump leaking outside itself.
 
Yes I have saw them leak where they are put together ( not on a 6.2 but the same idea )
 
Yes they have a diaphram inside that can break and leak. I just replaced the one on my yota because of this.
 
yep, i've seen it happen at the factory made seal where they're put together like lugnut said.
 
Yep, they can go either way, I'd preffer external leaks myself.

When you get the new pump, you will notice a smae "weep" hole in the cast portion of the pump, this is why it is there.
 
Thanks all!

I wonder if this has to do with the new ULSD fuel? I heard that the lift pump was the number one thing on 6.2s guaranteed to need replacement after running biodiesel for a while, so I I bet it's a problem with ULSD also.

I have only ever run one 3/4 tank of B20 biodiesel, so I don't think that would have done it.

Or it just could have been the lift pump's time to go. :) 127k miles.
 
Come on Richard, AGE had absolutely nothing to do with it !!
 
You are right - 1990 Burb means only 17 years old. It should last way longer than that. ;)
 
I just replaced the lift pump on my 6.2 and it was leaking at the "seam" on the top side of the pump.

Unless you have really small hands I would recommend that you consider undoing the motor mount on the passenger side and jacking the motor up an few inches (which I did not do). My hand was cramping up squeezing under the manifold to put those bolts in.
 
There's no way it can leak. It must be something else.











Don't mind me, I just wanted to go against the grain :flipoff2:
 
ajbirken said:
I just replaced the lift pump on my 6.2 and it was leaking at the "seam" on the top side of the pump.
Unless you have really small hands I would recommend that you consider undoing the motor mount on the passenger side and jacking the motor up an few inches (which I did not do). My hand was cramping up squeezing under the manifold to put those bolts in.
Click to expand...

Good idea - thanks! I already had enough trouble just replacing the hose clamps last night - not much space in that area. I'll have my engine hoist ready if needed. Might go ahead and replace the motor mounts while I'm in there, if I'm going to have the hoist hooked to it already. We'll see how ambitious I get. :) You know I really need to be worried about the stock motor mounts holding against that 6.2 torque. :lol:
 
ajbirken said:
I just replaced the lift pump on my 6.2 and it was leaking at the "seam" on the top side of the pump.
Click to expand...

Oh yeah - where did you get your replacement pump? Since it is kind of a pain to change, I want to make sure I get a good one.
 
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