fuel pump leak??

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nickd
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fuel pump leak??

Post by nickd » Fri Nov 04, 2011 5:01 am

My fuel pump is leaking and it appears to be dripping from the crimped seam that joins the top to the bottom of the fuel pump. I have changed and/or tightened the hose connections and it still leaks. Any one else experience this? I have a new one on the way.
1986 M998 & M1102 trailer
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dunsbr
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Re: fuel pump leak??

Post by dunsbr » Fri Nov 04, 2011 7:04 am

Hi Nick,

The normal mode of failure for this style of pump is a split diaphragm inside the pump.
This then allows fuel into the top side of the pump where it can leak out the breather and other gaps.
If this is your problem, be aware that it also allows diesel to leak into the engine oil diluting its lubricating properties.
So check your oil level and its viscosity regularly.

I hope this helps

Cheers
Brad Dunstan
RHD '87 M1026
(with 4L80E Trans, 242 T/case, 12K hubs, CTIS, A2 wiring, Air Con, A2 ebrake, 9k Winch,
Serpentine Belt Accessory Drive & Eaton e-lockers)

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Re: fuel pump leak??

Post by gestut » Thu Nov 05, 2020 2:21 pm

I am seeing the same think. It took me a while to figure out that the leak was not from the hose . As the engine got hot it starts leaking from the seam as mentioned above. What I dont understand is how does the fuel get in the engine if it's leaking. I know there is a vent line on the pump but not sure where its connected. Can you help me understand how the fuel will get in engine and mix with oil. I am now concerned 😟

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Re: fuel pump leak??

Post by Action » Thu Nov 05, 2020 4:32 pm

I found the seam leak earlier this year. I put an auto parts store replacement on. Then a month ago, I found out it wasn't pushing fuel. I rut on a real AC Delco part and it works great.

Jason

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Re: fuel pump leak??

Post by gestut » Thu Nov 05, 2020 4:40 pm

I got a oem on the way. Is it ok to drive like that with the leak?

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Re: fuel pump leak??

Post by lkgindy » Thu Nov 05, 2020 6:42 pm

gestut wrote:
Thu Nov 05, 2020 2:21 pm
I am seeing the same think. It took me a while to figure out that the leak was not from the hose . As the engine got hot it starts leaking from the seam as mentioned above. What I dont understand is how does the fuel get in the engine if it's leaking. I know there is a vent line on the pump but not sure where its connected. Can you help me understand how the fuel will get in engine and mix with oil. I am now concerned 😟
There is a diaphragm inside the pump that will split/rupture with age and allow the fuel to leak into the oil pan.

Larry
1987 M-998 Project
1995 Hummer HT

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Re: fuel pump leak??

Post by gestut » Thu Nov 05, 2020 7:07 pm

Thanks larry. I am just curious how. Will the oil travel thru the vent line and then in to to the oil pan?

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Re: fuel pump leak??

Post by lkgindy » Fri Nov 06, 2020 4:29 am

It will leak directly into the block and then down into the oil pan where the pump bolts to the engine block. The fuel pump actuating arm opening has a direct passage directly into the block/pan. When the diaphragm fails, the fuel then flows past the arm and into the pan.

Larry
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1995 Hummer HT

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Re: fuel pump leak??

Post by gestut » Fri Nov 06, 2020 6:43 am

Oh got it now. Thanks

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Hell On Wheels
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Re: fuel pump leak??

Post by Hell On Wheels » Sat Nov 21, 2020 9:09 am

In fact I just had this same problem from a pump I changed 5 months ago so basically it only lasted 5 months leaking at the seam.
Robert

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1986 - M998
2007 - M1102
2009 - H3T

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Re: fuel pump leak??

Post by gestut » Sat Nov 21, 2020 7:12 pm

Where did you buy the pump from?

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Hell On Wheels
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Re: fuel pump leak??

Post by Hell On Wheels » Sat Nov 21, 2020 9:20 pm

In an earlier discussion they mentioned at the local parts stores have them. I have built my stash of parts i have been collecting for a while but the local parts stores can supply them as well as eBay here is the information: M998 FUEL PUMP W/ GASKET HUMVEE HMMWV 12342893 2910-01-168-7905
Robert

1966 - M151A1
1986 - M998
2007 - M1102
2009 - H3T

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Re: fuel pump leak??

Post by gestut » Sat Nov 21, 2020 9:34 pm

Yeah what i was getting is all the local part store most of those pumps are made in china hence the 5 months ?

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Re: fuel pump leak??

Post by Action » Sun Nov 22, 2020 2:01 am

My leaky seam pump came on my engine from a demil truck.
My parts store pump had a lever that now moves 1/2” before engaging.
My current AC Delco is working great.

Jason

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Re: fuel pump leak??

Post by gestut » Sun Nov 22, 2020 8:48 am

I see. I just installed a mil surplus pump. Lets see how long that last. Do you have the ac delco part #? Thanks


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