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Discussion Starter #1
Hi all.
My Suburban has recently been leaving a large spot under the rear part of the engine where it joins the transmission. Checked all fluid levels. All good. Not sure...believe it is fuel. It will evaporate after a few days leaving just a small oily spot. Can also smell fuel under the hood. I cannot however find any leaks. Thinking maybe under the filter housing? Anyone have any idea? Experience the same thing.
Thanks

Rod
 

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There is a drain hole from the valley so any fuel leaning around the intake will end up there. The fuel filter housing is a common place for leaks. You could have old hoses leaking. You could have the O rings for the heater and water sensor leaking. You could have the sensors themselves leaking. The injection pump also has some places that could leak fuel but those are not nearly as common on these as leaks in and around the filter assembly.



A vendor like Leroy diesel sells the O rings in a kit so that is an easy way to do it. The water sensor isn't that unusual but the heater one is bigger than what comes in most assortments.


If you are going in most of us replace all the hoses as well as the o rings and while we are there we also relocate it just to make it easier to work with in the future. Most people raise it up on threaded rod. My solution which I thought was easier and gives more space was to just bolt it under one of the upper plenum bolts. That raises it high enough that its easy to route the hoses and change filters and doesn't require any new hardware other than the hoses that you already plan on replacing.
 

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There are also 3 hoses going in and out of the fuel filter housing aka FFM in addition to the o-rings.

Those are know to leaks.
2 of them are snaking under the intake so definitely difficult to see if it is leaking.
 

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Discussion Starter #5
Hi all. After a couple busy weeks I finally got a chance to take a good look for my fuel leak. Not at the firm like I thought. It is actually from the small return hose at the front. Leaking at both ends. 😬
If it turns out to be more I will let y’all know.

Rod
 

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Just replace the hose there...

I personally like to bypass that return rail that runs under the intake... if that's the one your talking about. I hate that thing. If it's on the 96-02/03s? It's on the 1st gens. Hated that stupid return rail. Lol
 
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