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Old 24-03-2017, 06:41   #1
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Yanmar 2QM20 (H) Fuel Problem

1979 Endeavor 32

Forgive me in advance for being so long winded. But in this case, I think more information might be better. For the 'bottom line' kinda person, skip to the last paragraph.

First mistake:
I bought a boat that had been neglected. What I wasn't told was that it had a re-occurring fuel problem. So here is the skinny:

This boat sat for almost 4 years because every now and again the fuel system would just quit delivering fuel. The only way to get it to start again was to completely bleed the system. Because of this, the previous owner replaced the high-pressure fuel pump, serviced the injectors, added an electric fuel pump and a Racor fuel filter, but all to no avail.

This first problem was solved with the help of a Marine Engineer name William Davies whom I met in Savanna Georgia some 2 months after I began working on the problem.: After 12 hours of ripping into the fuel system (he loves a good puzzle) he found a small bit of paper was caught in the 90 degree fitting at the top of the pickup tube on the fuel tank. It acted like a whimsical little check valve with a will of it's own, shutting off fuel whenever it felt so inclined. Evidently it was a portion of a parts sticker (circa pre-1978) that was not completely pealed off before the tank was assembled. It probably dislodged when newer fuel additives dissolved it's adhesive.

The second problem was almost as elusive as the first. The (less than a year old) high-pressure fuel pump quit delivering fuel. The cylinders were evidently sticking and were ultimately freed up when straight Lucas fuel treatment was used by Scott Russ, a delivery captain and USCG Machinist Mate Retired I hired. One of the better decisions I made.

He filled the secondary fuel filter (the one mounted on the engine) to the top with straight Lucas fuel treatment. Then, he opened the decompression valve and spun the engine long enough to completely fill the high-pressure pump with the Lucas and let it sit. When we got back from lunch, he fired the engine off with lubricating starter fluid to force the Lucas through the injectors under pressure. Again he let it sit. Finally, he started it and kept it running with starter fluid until it would run on its own. It hummed like neon sign.

I am in the middle of trying to deliver this boat to my home port in Galveston Bay.Near Panama City Florida right now. Hope to make a weather window for NOLA before April 1.

A list of fuel system upgrades: Fuel system from tank to lift pump has been rebuilt and relocated. New fuel lines throughout. New fuel pump. New fittings with no 90 degree angles. This configuration placed the electric pump and Racor filter level with the bottom of the fuel tank to insure gravity feed to the fuel pump. Tank cleaned and fuel polished. All new fuel filter elements.

This was tested on a near non-stop run from Fernandina, Florida south, across the Okeechobee then north to Dunedin/Clearwater area via the ICW, It ran fine for 5 days of near 24 hour a day service; Average speed about 5.5 knots; Average distance traveled was about 125 miles per day; Average fuel consumption less than 6 gallons per day.

Then the fuel system failed again, this time due to bad fuel. When we started out, the 20 gal tank was filled with good fuel. We filled four 5 gallon plastic cans in Fernandina and added less than 6 gals a day for the first 2 days and then refilled the cans (except for 1) and the tank in Fort Myers.

When the engine failed in Dunedin, the fuel in the canister that had not been used since Fernandina was absolutely black with rubber particulates from the decomposing fuel supply lines that ran out to the fuel dock there. The rubber has made the cylinders in the high-pressure fuel pump sticky again so it was back to doing its old tricks.

As a preventative measure, I have installed a new pickup tube in the fuel tank and will be using the old tube in a different port as a return line for an ad hoc polishing system. It will run as long as the key is on. I bought a Carter 78 gallon/hour electric fuel pump and another Racor for that purpose.

So here is my question. Is there a better lubricant/treatment than the Lucas that might clean the rubber out from the high-pressure fuel pump and injectors? I am getting REALLY tired of bleeding this fuel system. The fact that it will run for hundreds of miles and then stop when you least expect it is also a bit problematic.
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Old 24-03-2017, 13:03   #2
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Re: Yanmar 2QM20 (H) Fuel Problem

Lucas fuel treatment is a good product. That said I'm a cheap skate so for the last 20 years I've been using 2 stroke outboard oil as an additive to lubricate my in line jerk pump.
Since the clean air act and EPA forced ultra low sulfur diesel fuel on us there have been cases of plungers sticking in the bores of the high pressure pumping elements. Some have advocated adding old motor oil to the fuel. BIG NO NO!!! Same with ATF. Don't do it. Both contain additives for wear prevention, anti sludge deposits, and a few other things that don't burn completely. The 2 stroke oil lubricates and burns clean.
As far as cleaning out rubber particles already in the system I can only recommend completely cleaning out the system. The clearances are so small in the pump plungers and barrels that any dirt will cause wear and damage.
If the rubber particles were in the jugs and then dumped in the tank the Filters should have stopped them.
Good luck and let us know how it works out so we all learn.
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Old 24-03-2017, 14:50   #3
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Re: Yanmar 2QM20 (H) Fuel Problem

Quote:
Originally Posted by Diesel Bill View Post
Lucas fuel treatment is a good product. That said I'm a cheap skate so for the last 20 years I've been using 2 stroke outboard oil as an additive to lubricate my in line jerk pump.
Since the clean air act and EPA forced ultra low sulfur diesel fuel on us there have been cases of plungers sticking in the bores of the high pressure pumping elements. Some have advocated adding old motor oil to the fuel. BIG NO NO!!! Same with ATF. Don't do it. Both contain additives for wear prevention, anti sludge deposits, and a few other things that don't burn completely. The 2 stroke oil lubricates and burns clean.
As far as cleaning out rubber particles already in the system I can only recommend completely cleaning out the system. The clearances are so small in the pump plungers and barrels that any dirt will cause wear and damage.
If the rubber particles were in the jugs and then dumped in the tank the Filters should have stopped them.
Good luck and let us know how it works out so we all learn.
Thanks Diesel Bill!

Good information. Certainly nothing with which I would disagree.

I had read somewhere about a class of lubricant that encapsulate particulate matter. Old rubber get sticky as it breaks down. It will start to make clumps. This type of lubricant prevents that from happening. That is a wonderful quality when dealing with tight tolerances.

I can't remember the name, or for that matter where I read it. It was a long shot, but I was hoping someone might suggest it.
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