Recently purchased a 2001 Hunter 320 with a 18 Hp Yanmar. Motor wasn't well maintained but always had Oil. Motor starts OK when cold but won't idle down even when throttle is backed off. When motor is warmed up it stalls at low rpm and won't restart. Compression is Ok and injector spay is good. What else should I check? Thanks The Breezer
- Status
Take off the mixing elbow
and inspect that for buildup. If the problem is not that, you at least want to know what kind of condition it is in to eliminate it as the problem. Clean it up while it is out. If it is not that, then Fuel would be my next place. About 90 percent of problems posted here are because of fuel issues - from the tank to the filter, clogged filter, leaking line(air) etc.... it usually comes down to fuel with diesels. Good luck.
and inspect that for buildup. If the problem is not that, you at least want to know what kind of condition it is in to eliminate it as the problem. Clean it up while it is out. If it is not that, then Fuel would be my next place. About 90 percent of problems posted here are because of fuel issues - from the tank to the filter, clogged filter, leaking line(air) etc.... it usually comes down to fuel with diesels. Good luck.
Hire a certified Yanmar mechanic.
B: Hire a certified Yanmar mechanic and have him take you thru the engine. Be sure that everything is up to spec. This will be the best $200-300 that you will spend. I good guy will show you all the things to look for and see if there are issues that the average Joe will miss.
B: Hire a certified Yanmar mechanic and have him take you thru the engine. Be sure that everything is up to spec. This will be the best $200-300 that you will spend. I good guy will show you all the things to look for and see if there are issues that the average Joe will miss.
Fuel
I second the previous suggestion that its a fuel problem. I recommend checking the primary fuel/water separator filter, and changing the secondary (cheap enough). Then bleed the fuel system. Make sure that if your installation includes an electric lift pump, that it is indeed energized; incidentally, I hot-wire my lift pump to make bleeding the fuel system easier. It could also be a problem with the high pressure fuel pump/fuel distributor, the pump that raises the pressure immediately before the injectors. Finally, it could be that the fuel cut-off is not completely in the ON position when the eingine is running - check it! I had this problem once.
I second the previous suggestion that its a fuel problem. I recommend checking the primary fuel/water separator filter, and changing the secondary (cheap enough). Then bleed the fuel system. Make sure that if your installation includes an electric lift pump, that it is indeed energized; incidentally, I hot-wire my lift pump to make bleeding the fuel system easier. It could also be a problem with the high pressure fuel pump/fuel distributor, the pump that raises the pressure immediately before the injectors. Finally, it could be that the fuel cut-off is not completely in the ON position when the eingine is running - check it! I had this problem once.
check your fuel lines
Just had a friend have a similar experience with a somewhat older boat. Engine stall turned out to be the result of a deteriorated fuel line. The rubber fuel hose looked good as installed. When he pulled it off to set it aside to reinstall the fuel pump, he noticed fuel drippage where he laid it after plugging the ends. As he picked up the hose to clean up, he flexed it, and it had exterior age cracking which was invisible when originally checked in its installed position. Hose replaced, engine runs fine. It might not be your problrm, but wortha look.
Just had a friend have a similar experience with a somewhat older boat. Engine stall turned out to be the result of a deteriorated fuel line. The rubber fuel hose looked good as installed. When he pulled it off to set it aside to reinstall the fuel pump, he noticed fuel drippage where he laid it after plugging the ends. As he picked up the hose to clean up, he flexed it, and it had exterior age cracking which was invisible when originally checked in its installed position. Hose replaced, engine runs fine. It might not be your problrm, but wortha look.
2GM20F Total fuel system maintenance.
The Yanmar 2GM20F has its throttle linkage and fuel pump on the starboard side. The throttle stop near the front of the engine is an adjuatable mechanical linkage with a screw in screw out adjustment and a lock nut on one side. You can look at and replace any OEM rubber fuel line as the new CG approved line is resistant to alcohol and diesel and is a noticeably larger (about 1/2") Outside Diamenter with the same 1/4" ID. The flexible fuel line runs from the tank to the Fram (oe Raycor) fuel filter, check fuel line ends at the hose clamps for cracks and replace; then on to the manual lift fuel pump at about mid point of the engine on the starboard side. Wipe down with a clean paper towel to find leaks. From there a hard copper fuel line with banjo fittings leaves the fuel pump and goes to the small Yanmar 2 micron canister filter (two bleed screws on top) on the front stbd side, the top ring screws off to drop the aluminum canister and remove the paper filter from the inside, replace the 'O' ring when you replace the filter; then a banjo fiting and flexible fuel line from that filter with SS mesh outer wrap goes to the high pressure pump with a bleed screw at the banjo fitting at the pump end. Don't mess with the high pressure pump! From the high pressure pump two copper lines run to the injectors and a flexible fuel return line runs from the injectors back to the tank. That's the whole fuel system; so changing out the flexible fuel lines and the filters then bleeding the system isn't that difficult. There is no electric fuel pump as OEM equipment and the mechanical pump driven off the engine cam seems to last forever (replace it if the diaphram is leaking). Replace any washers under any bleed screws you open and replace any copper washers on any banjo fitings you open or any which are leaking. You may solve the problem by eliminating any air or fuel leaks in the fuel system. Do not use any sealants on any Diesel fuel fittings ever! That's where the soft copper washers are used. While you are at this you, might pump out the fuel tank to make sure there is no sediment build up. I cut in and installed a Seafit access port to clean the poly tank and eliminate that issue. Post any specific questions for follow-up.
The Yanmar 2GM20F has its throttle linkage and fuel pump on the starboard side. The throttle stop near the front of the engine is an adjuatable mechanical linkage with a screw in screw out adjustment and a lock nut on one side. You can look at and replace any OEM rubber fuel line as the new CG approved line is resistant to alcohol and diesel and is a noticeably larger (about 1/2") Outside Diamenter with the same 1/4" ID. The flexible fuel line runs from the tank to the Fram (oe Raycor) fuel filter, check fuel line ends at the hose clamps for cracks and replace; then on to the manual lift fuel pump at about mid point of the engine on the starboard side. Wipe down with a clean paper towel to find leaks. From there a hard copper fuel line with banjo fittings leaves the fuel pump and goes to the small Yanmar 2 micron canister filter (two bleed screws on top) on the front stbd side, the top ring screws off to drop the aluminum canister and remove the paper filter from the inside, replace the 'O' ring when you replace the filter; then a banjo fiting and flexible fuel line from that filter with SS mesh outer wrap goes to the high pressure pump with a bleed screw at the banjo fitting at the pump end. Don't mess with the high pressure pump! From the high pressure pump two copper lines run to the injectors and a flexible fuel return line runs from the injectors back to the tank. That's the whole fuel system; so changing out the flexible fuel lines and the filters then bleeding the system isn't that difficult. There is no electric fuel pump as OEM equipment and the mechanical pump driven off the engine cam seems to last forever (replace it if the diaphram is leaking). Replace any washers under any bleed screws you open and replace any copper washers on any banjo fitings you open or any which are leaking. You may solve the problem by eliminating any air or fuel leaks in the fuel system. Do not use any sealants on any Diesel fuel fittings ever! That's where the soft copper washers are used. While you are at this you, might pump out the fuel tank to make sure there is no sediment build up. I cut in and installed a Seafit access port to clean the poly tank and eliminate that issue. Post any specific questions for follow-up.
- Status