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Author Topic: Fuel Pump Leaking  (Read 73 times)

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Offline GunnersWillys

Fuel Pump Leaking
« on: November 24, 2019, 01:45:27 PM »
Wow, I've been looking for the source of a fuel smell.  This morning it revealed itself. 

On the pump, 180 degrees out from the engine, just below the flange, there are two holes in the side of pump.  One of those is aggressively leaking, or appears to be anyway. While on the engine and being turned over it really cut loose.  Happening within a half inch of that location, and it's not the gasket.  Kind of hard to see and I was concerned about fire, so I stopped.

What are these?  Is there a way to fix it?  I poked around a bit on the site and don't see anything.  I haven't disassembled yet, but hope to later today.



Offline Rus Curtis

Re: Fuel Pump Leaking
« Reply #1 on: November 24, 2019, 02:07:31 PM »
I wonder if they're like "weeping holes" you'd find on a water pump?

Never been inside one before but would assume the diaphragm is probably to blame.

'54 CJ-3B "Green Gruntt"
Bantam T3-C

Offline Squishymonster

Re: Fuel Pump Leaking
« Reply #2 on: November 24, 2019, 02:50:46 PM »
I'm not familiar with these pumps at all, so this is just a thought. I had recently been studying general pump design though.

Normally the top section of the pump handles the inlet and outlet of fuel. The fuel shouldn't pass lower than the rubber diaphragm or gasket that is above the two holes. However the diaphragm has ruptured and fuel is moving below it, and coming out the holes. I think the holes are to let atmospheric pressure in and high pressure air out during diaphragm movement. That's my guess without ever having looked inside that particular pump - I bet you need to open it up and order a new diaphragm. I am guessing by the shape this is a diaphragm pump, not an impeller - I know my 48 has one of the glass diaphragm pumps.

Offline GunnersWillys

Re: Fuel Pump Leaking
« Reply #3 on: November 24, 2019, 03:33:13 PM »
I had it off and the screws around the flange were loose, so I tightened and re-installed (that took two hours, stupid bolts).  Now it won't pump any fuel at all.  That supports everyone's theory.  I'll pull it back off and disassemble down to the diaphragm and let you know what I find.

Offline athawk11

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Re: Fuel Pump Leaking
« Reply #4 on: November 24, 2019, 03:34:43 PM »
Leaking from these holes is a sure sign of diaphragm failure.  There is no easy fix.  This pump (AC-9562) required a rebuild when it began leaking from this hole. 

They are kind of fun to rebuild.

2-1949 CJ3As
1-1946 CJ2A

Offline GunnersWillys

Re: Fuel Pump Leaking
« Reply #5 on: November 24, 2019, 04:37:28 PM »
Walcks has a replacement for $ 90.  I'll order one in the morning.  Lot simpler for that price than trying to rebuild. 

Offline Bob W

Re: Fuel Pump Leaking
« Reply #6 on: November 24, 2019, 08:06:11 PM »
Be sure to check for fuel in the engine oil.
Bob W

Offline GunnersWillys

Re: Fuel Pump Leaking
« Reply #7 on: November 24, 2019, 08:37:11 PM »
Thanks!  I hadnít thought of fuel in the engine oil.   Will most definitely check!