Have a 3GM30F Yanmar 24hp in my sailboat. Ran well for about 2 hours at 2200RPM, then experienced loss of power and varying RPM, high of 2200 - low of 1000. The engine was doing this on its own, sometimes seeming like it would stall. This lasted for about an hour until I got back to the boat slip. Is this a sign of bad diesel fuel?
Loss of Power
- Thread starter kmarsicola
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Yup.. Clogged filter (from bad fuel) or a clogged fuel pick-up inside the tank. Some pick-ups have a little screen inside the tip . This screen can plug and do what you are describing. Most folks pull the pick-up tube out and pull the screen and re-install the tube. The primary filter will catch anything that the screen would have.
After several fuel filter changes, polishing fuel, finally found the culprit. The pick up tube in the fuel tank has a screen on it that was mostly clogged with hard crusty carbon crud. My motoring symptoms were exactly like yours until the power was needed and it couldn't pass enough fuel for the demand. Here is a pic of the little bugger.
Kamper
Hunter 45 Legend
O'side, CA
Kamper
Hunter 45 Legend
O'side, CA
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Thank you gentlemen. I will start there and replace the fuel filter too. Just bought the boat in Marina Del Rey, was moving it down to Long Beach when I had the engine trouble. I think the boat was sitting for awhile. I will probably get the tank polished too. I was hoping it wasn't something like injectors or worse.
Also give a look
You might also check the fuel tank vent line. One time I had a dirt dauber nest in vent line, which can and did cause very similar problem. Sounds like most definately a fuel starvation problem.
You might also check the fuel tank vent line. One time I had a dirt dauber nest in vent line, which can and did cause very similar problem. Sounds like most definately a fuel starvation problem.
When the power loss starts open the fuel fill cap and see if the power picks up. If it does then look for a clogged vent, if it doesn't then you have quickly eliminated the vent.
Fred
Fred
I experienced exactly the symptons you are describing on our delivery trip last year. They were intermittent, sometimes really bad, sometimes the engien ran great for hours on end.
We went through all the steps decribed in previous answers, changed all filters, wchecked the pickup tube etc. For us, the culprit was the electric fuel lift pump which was in its deat throes. Replaced it with a generic marine / diesel pump from Napa and have had happy motoring ever since.
Cheers
Matt
We went through all the steps decribed in previous answers, changed all filters, wchecked the pickup tube etc. For us, the culprit was the electric fuel lift pump which was in its deat throes. Replaced it with a generic marine / diesel pump from Napa and have had happy motoring ever since.
Cheers
Matt
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