This past weekend we had the boat out for one of our rare occassions this summer and as you would figure the wind died to nothing after we were out a ways. Ended up motoring back to the dock, which is not a bad idea as we need to run the motor more. I cranked it up to 3200 rpm's and it ran fine at around 6.8 knots for about 30 minutes. It then start to drop rpms down to 2500 and then run up again. There was no smoke coming out so I figured it was a little junk in the fuel that would works its way out. It didn't and continued to run irregularly. I finally dropped the rpms down to 2800 and it ran fine the rest of the way in. I had the engine tuned up last year in Oct which included changing all the filters. I burned thru a tank of fuel after that during the Harvest Moon Regatta and filled the tank at that time(Oct 06). There is still 3/4 of a tank of fuel as we have not used the engine that much since then. It appears to me to be a fuel problem but I could be wrong. Any ideas?
Yanmar running irregular
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Yep
Might be your Texas climate. Assuming that you have a water-separator fuel filter, check it for water and go from there. You do have a clear bowl (see through), right?
Might be your Texas climate. Assuming that you have a water-separator fuel filter, check it for water and go from there. You do have a clear bowl (see through), right?
Starving for something
It is getting either starved for fuel or air, not much else that would cause that kind of running. A plugged fuel tank vent is all I can think of that would cause the slow surging you are describing.
It is getting either starved for fuel or air, not much else that would cause that kind of running. A plugged fuel tank vent is all I can think of that would cause the slow surging you are describing.
Fuel Filter
Try changing the primary fuel filter. Also are you using a biocide treatment in your fuel tank when you fill up? Gary Wyngarden S/V Wanderlust h37.5
Try changing the primary fuel filter. Also are you using a biocide treatment in your fuel tank when you fill up? Gary Wyngarden S/V Wanderlust h37.5
Thanks
Thanks guys for the advice. Gary, yes I do use a biocide treatment in my tank when I fill it. And yes Fred I do have a clear bowl water-separator fuel filter. I will change the primary fuel filter and check the water separator filter as well. Didn't think about the vent for the tank. I'll check thas well. We do have a problem with dirt dobbers building nests in the vent lines. Should have thought about that as I use to have a 7 hp Honda outboard and a dirt dobber built a nest in the air vent which caused the same problem. Thanks again, I knew I could count on you guys to pin point the problem. Getting ready to do the Harvest Moon Regatta in a month and don't want any engin problem. Gary, Fred, my son lives in the Seattle area now and he said you had some pretty nice weather this summer. I hope we have a nice fall as the summer was terrible with all the rain we had. Tom S/V At Last
Thanks guys for the advice. Gary, yes I do use a biocide treatment in my tank when I fill it. And yes Fred I do have a clear bowl water-separator fuel filter. I will change the primary fuel filter and check the water separator filter as well. Didn't think about the vent for the tank. I'll check thas well. We do have a problem with dirt dobbers building nests in the vent lines. Should have thought about that as I use to have a 7 hp Honda outboard and a dirt dobber built a nest in the air vent which caused the same problem. Thanks again, I knew I could count on you guys to pin point the problem. Getting ready to do the Harvest Moon Regatta in a month and don't want any engin problem. Gary, Fred, my son lives in the Seattle area now and he said you had some pretty nice weather this summer. I hope we have a nice fall as the summer was terrible with all the rain we had. Tom S/V At Last
Pick up tube
I had a Hunter 30 (now I have a 37.5). On my 30 I had the same problem you report. Ot the end of the pick up tube (the fuel intake tube which goes into the tank and close to the bottom) has a screen. Sometimes bits of junk get picked up, amalgamate together and form a little wad of guck. Take the tube out and pry the screen with a screwdriver then throw it away. The filters will take care of junk, Mike
I had a Hunter 30 (now I have a 37.5). On my 30 I had the same problem you report. Ot the end of the pick up tube (the fuel intake tube which goes into the tank and close to the bottom) has a screen. Sometimes bits of junk get picked up, amalgamate together and form a little wad of guck. Take the tube out and pry the screen with a screwdriver then throw it away. The filters will take care of junk, Mike
Same thing happened...
yesterday on the boat I race on. Primary filter change and a bleed-down and problem solved.
yesterday on the boat I race on. Primary filter change and a bleed-down and problem solved.
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