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Author Topic: Injector Pump Fuel Leak  (Read 953 times)

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Bill Vensel

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Injector Pump Fuel Leak
« on: December 24, 2016, 02:20:47 PM »

This is my first post, and first of all, a big THANK YOU to you all for the great education you've provided.  I've been reading and searching the forum and tech notes,  and have found ideas, solutions and approaches to a variety of mechanical and electrical problems. So thank you to you all.

I resolved an issue that I did not see discussed, so thought I'd share here. Namaste has an M25XP.  I noticed fuel seeping out of the top of my injector pump. The high pressure fuel lines to the injectors connect to a part identified in the tech manual as the "delivery valve holder." It is a bolt like item that screws into the pump housing. It is hollow with a spring inside, the "delivery valve spring." No matter how hard I tightened it, fuel still made its way through the threads. On disassembly I found an o-ring at the top of the threads on each holder. It appeared that these rings had failed, and thus the leaks. I couldn't find any info on the rings, no part number or even size, but I found that a 9/16" ring fit perfectly. I replaced the rings on all three holders, reassembled, and no more leak. 

The tech manual did not show the rings, and I found them kind of by accident. Now it seems like a simple and obvious solution, but this amateur mechanic was stumped for a while. So I offer this for other amateur mechanics who might have a similar problem.
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britinusa

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Re: Injector Pump Fuel Leak
« Reply #1 on: December 25, 2016, 06:08:35 AM »

Do you have any more info on the o-ring? Might be a good item to keep in the Engine Spares Box.

Paul
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Paul & Peggy
1987 C34 Tall Rig Fin Keel - Hull # 463

See you out on the water

Engine:M25XP

Bill Vensel

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Re: Injector Pump Fuel Leak
« Reply #2 on: December 25, 2016, 09:32:09 AM »

I wasn't sure of the size before disassembly, and so I bought a package of a variety of sizes at West Marine, then matched up to the old ones. Turns out the 9/16" was the best match. So now I have a bunch of o-rings, some larger and some smaller in my locker. The pack was about $8.00, but I figured it not a bad idea to have some on hand.

Bill
C34 #980, Namaste
Charlotte Harbor, FL
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Ron Hill

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Re: Injector Pump Fuel Leak
« Reply #3 on: December 25, 2016, 12:40:19 PM »

Bill : Go to a place where they repairs diesel injectors and injection pumps. 

I'm sure that the "O" ring is metric!!

A thought

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Bill Vensel

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Re: Injector Pump Fuel Leak
« Reply #4 on: December 25, 2016, 03:48:52 PM »

Thanks, Ron. I'm sure you are right. I was using my metric wrenches for the job. A conversion chart shows the equivalent to be about 14 or 15 mm.
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Re: Injector Pump Fuel Leak
« Reply #5 on: August 04, 2022, 12:49:42 PM »

Any idea what the torque is on those delivery valve holders? I also need to change out those o-rings and am afraid of over tightening!
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Ron Hill

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Re: Injector Pump Fuel Leak
« Reply #6 on: August 04, 2022, 01:56:46 PM »

Switch : I gave away my shop manual on the M25Xp when I changed engines. 

I'd use a spark plug torque of 15-18 Foot Pounds.  That's snug - you can tighten more if you see fit!!

A thought
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Ron, Apache #788

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Re: Injector Pump Fuel Leak
« Reply #7 on: August 09, 2022, 01:25:40 PM »

Thanks Ron! :)
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Ron Hill

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Re: Injector Pump Fuel Leak
« Reply #8 on: August 09, 2022, 02:41:08 PM »

Guys : I was in Auto Zone and found that they have both ASE and Metric assorted "O" rings is small boxes.  Other auto supply store might also have them!!

A thought
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