Yanmar problem solved...

[Warren Milberg]

Some time ago, there was a thread going here about "fuel polishing." A friend of mine who has a Pearson 28-II with the same engine as mine -- 1986 Yanmar 2GM20F -- decided to have this fuel polished by a mobile polisher. This was an expensive proposition (+/-$400), but he thought it would clean out his tank and improve the quality of his fuel. Up until that time, he had had no fuel related, or any, engine problems. After the fuel polishing, he experienced a number of engine failures, usually after the engine had been running for some time. He got a lot of experience with getting towed back to his slip. He also lost confidence in his boat. He keeps his boat at a marina that has an authorized Yanmar mechanic, who he engaged to find the problem after he and I tried a number of things that didn't fix it (i.e, replaced both filters a number of times, blew out the fuel vent, checked the mixing elbow, pulled and inspected injectors, removed the screen on the fuel uptake tube, etc.). The Yanmar mechanic (+/-$80 an hour) also tried a number of things to fix this vexing problem of the engine quitting just when you need it. To make this long and windy story less so, it turns the problem was that the fuel polishing loosened a lot crud that would slop around in the tank and eventually clog the fuel uptake tube. Once the engine was shut off and the boat settled for a while, the engine would always restart. He has since added a fuel tank access port and his tank has been scrubbed clean. No problems since...

Remmeber the physician's motto: "First Do No Harm."

 

[Don S/V ILLusion]

Good to know Warren

thanks for reiterating the story for us. I would never have thought enough crud could actually clog the uptake tube without a screen on it.

 

[Ross]

400 Dollars for polishing 10 gallons of fuel?

How much does a new tank cost? If the contract fuel polisher loosened the crud shouldn't the polishing have removed it and trapped it in his filters?

 

[RichH]

Not necessarily .....

Loosening of the crud is no guarantee that it will be captured in the filters. Much of this 'deposition' on the tank walls (bio-resins, dead cells, etc.) is by soft/deformable particles/gels which will/can quickly 'extrude' through common nominally rated 5-10µM 'filters', especially if there is a high differential pressure across the filters.

The scrubbing is the most effective for crud removal, then a tank rinse ....THEN you recirculation polish the fuel. Most commercial fuel polishers know or should know better.

 

[Rich Stidger]

Years ago a friend had a similar problem

He also had a Pearson (about 40 feet) and the engine would cut out whent he tank was below half full. After stopping for a shot while, the engine would restart OK but until the tank was full the problem would repeat.

The final solution was when the tank was opened and several "balls" of diesel bugs had conglomerated together. These were shaken into motion when the tank was not full and they would occasionally get sucked against the bottom of the pickup tube and would stop the fuel flow.

After the tank was scrubbed clean, the problem never recurred.

Who would have thunk?

 

[Don12364]

Whilst we have the attention of the pundits!

After my first dose of fuel bug I regarded the screen on the pickup tube as mans worst enemy and removed it thinking I could never clear this whilst under way.

After my second dose a couple of years later my entire fuel line and Racor filter became blocked solid. I ended up stripping the whole line out of the boat and taking it home and blowing it out on the air line. Again no hope of clearing it whilst away from base.

Now I ponder the wisdom of removing the little screen on the pickup tube.

Now I use "Fuel Set" religiously but if I ever get the bug again I intend to blow it back into the tank as a "get me home" by using my dinghy pump. It may be necessary to repeat this several times but I hope it will work. The pump is one of those piston pumps which do so well on an inflatable and can pump 5 psi.

Of course this would be much easier to do if the contamination only went in as far as the screen.

Was I right or wrong?

 

[s sauer]

Fuel Pick-up Tube

Having cut open the poly tank on our 28.5 and installed a 4" diameter 'Seafit' access panel I was able to completely clean the tank. There was no screen on the pick-up tube, which was approximately 3/8" in diameter and about 1/2" short of the bottom of the tank and cut at a 45 degree forward facing angle. There was some crud built up on the fuel gauge float assembly and a dirty film on the inside top and sides of the tank. The bottom wasn't bad at all after the old fuel dreggs were mopped out. I wiped it all clean with rags saturated in alcohol; replaced the fuel lines and changed the filters.
I believe this is the only way to know you have a clean tank and way less than $400; plus you can open it up and inspect, drain, or clean it any time you need to afterwards.