Yanmar 2GM20 issues

[lateron]

Hi guys, recently my very reliable 15year old Yanmar 2GM20 on my SO32 has developed a tendency for the engine speed to falter and slow down before [so far!] picking up again. Filters have been changed and were clean. Now suspecting faulty hoses or lift pump.I've bought an endoscope to look inside the tank. But haven't had chance yet.
Seems like fuel starvation? Any similar happenings out there?
Regards Ron

[sitara]

Hi Ron,

Partial blockage in the fuel intake? There have been other threads mentioning this. Maybe blow some compressed air down the fuel line from the filter to the pickup? Filters should have prevented anything from the tank to the fuel pump.

[NZL50505]

Agree fuel starvation sounds likely but if you don’t get a result from the usual ‘upstream’ checks then I’d suggest checking injectors. I had an old 3GM that starting losing power )initially at higher revs then eventually any speed) and it turned out the injector tips were toast and needed rebuilding.

[lateron]

Thanks guys. Currently going to run the engine from a gravity tank bypassing the fuel lines and lift pump so if it still does it then it may well be something like injectors. If it doesn't do it then maybe the tank/hoses/lift pump.

Cheers Ron

[MartyB]

For me, it was a combo of bad fuel pump on side of motor. $50 max.
Along with an item in the fuel tank that was clogging the fuel inlet to fuel pump. I also cleaned out via compressed air, the fuel lines, new copper washer in the line to make sure no air leaks where in these places.
For me, major issue was the item blocking the fuel line intake.

Marty

[lateron]

Hi again....well after bypassing the main tank and hoses to the lift pump the engine ran fine so it seemed the problem lay in the fuel hoses or tank pick up. Replaced those and tightened up all the joints and now seems ok. Hope it doesn't return !!
Ron