Fuel Contamination

[steveh2112]

hi all,

i can't get my engine (Yanmar 4JH3-HTE) to start

so i went to my boat today with the new fuel filters, bled the system all the way to the injectors and i noticed the fuel coming out of the injectors looks weird.

so i checked the fuel in the tank and there is a serious problem in there (see pic). the bottle on the left is what i took out of the water separator (1st stage) filter. the second stage fuel filter looks pretty much the same. the bottle on the right is fuel directly sucked from the tank. as you can see there is a MAJOR sediment problem and it's weirdly cloudy and off color. why it's so much worse in the filter than in the tank i can't explain, i guess it's just the place in the tank where the fuel intake sucks from is worse than where i took my sample from.

anyhow, clearly the tank needs emptying, the entire fuel system flushing and refilling. i can do that but my friend thinks it's dangerous to crank the engine over until the fuel pump is rebuilt, otherwise the crap that's in there now could make things worse.

what do you all think and how could the fuel get so bad? the boats in Thailand so hot and humid all the time.

thx steve

[boden36]

Any fuel in the pump would have passed through the filter. I would clean the tank, pump clean fuel through the system and then if you are still worried, crank the engine over with the injector lines loose until clean fuel comes out there.
If you have a deck fuel fill make sure it seals well.

Regards,
Richard.

[steveh2112]

Originally Posted by boden36

Any fuel in the pump would have passed through the filter. I would clean the tank, pump clean fuel through the system and then if you are still worried, crank the engine over with the injector lines loose until clean fuel comes out there.
If you have a deck fuel fill make sure it seals well.

Regards,
Richard.

i forgot to add a photo of the fuel coming out of the filter which i also sampled before i took the filter off, but basically it looked the same as the bottle on the left, massive amounts of sediment which i'm sure did make it into the pump.

[Kenomac]

Three words: Fuel Polishing System

http://www.cruisersforum.com/forums/...on-132030.html

Install a system, and your problems will disappear. Now is the best time to do it after you clean out your tanks.

BTW: We have the same Yanmar 4JH3-HTE turbo diesel.

[TeddyDiver]

Originally Posted by steveh2112

what do you all think and how could the fuel get so bad? the boats in Thailand so hot and humid all the time.

thx steve

Either your fuel has been in the tank a long time or more propably had a bad fill from a contaminated pump station, or both. Some water in diesel fuel and it starts to grow murky bacterias. To avoid that take a sample of the fuel in a clear jug before filling your tank, prefiltering all fuel while pumping and get a fuel polishing system. Two last ones can work through the same setup..

BR Teddy

[UNCIVILIZED]

Originally Posted by TeddyDiver

Either your fuel has been in the tank a long time or more propably had a bad fill from a contaminated pump station, or both. Some water in diesel fuel and it starts to grow murky bacterias. To avoid that take a sample of the fuel in a clear jug before filling your tank, prefiltering all fuel while pumping and get a fuel polishing system. Two last ones can work through the same setup..

BR Teddy

+1 on the above. And in additon, some of the moisture in the air in a tank will get into the fuel. Especially as the inside of the tank will sweat a bit, like most things do with temperature changes. Ergo, more moisture added to the fuel. And diesel is organic, so it's always growing stuff.
Also, the tank isn't fully immune to corrosion unless it's made out of polymer, or composite. So it's likely contributing to contaminating the fuel when things are left to sit, as well. Even if it's only a small amount.