I am having some trouble with my Yanmar 1GM and could use some guidance. The engine seems to run fine for about 30 minutes. After which the rpms start to drop and the engine eventually shuts off. To get the engine to run again I purge the fuel lines of air by opening the bleed screws and operating the manual pumping lever on the lift pump until fuel spurts out the lines. After bleeding the engine, it starts right up and runs for another 30 minutes or so and then quits, et cetera… The boat is new to me so I do not know how the engine behaved before. I have also noticed that at high rpms the engine will quit sooner than it would at lower rpms. Since discovering this problem, I pumped out the fuel in the tank and replaced the fuel thinking it could be dirty fuel. I also replaced the fuel filter and the fuel/water separator filter. But the problem still persists. I having a feeling that there is an air leak somewhere in my fuel system. My guess is the fuel filter housing is not sealing. But I am not sure. I tightened that thing down a tight as I could by hand. My other hunch is that the lift pump needs to be replaced. Do those things get old? Has anyone had a similar problem? How does one trouble shoot an air leak? Am I barking up the wrong tree? Any comments/suggestions welcome. Thanks in advance.
- Status
Don't know how to fix it but
Anthony: I think you are correct in assuming that you have some type of air leak. I believe that these engines consume about 1/2 gal of fuel per hour. If your engine dies after 30 min. this mean that you have about 1/4 gal. in the system before the air bubble gets to the injector/high pressure pump. Of course it will run longer at lower engine RPM's you are consuming less fuel. It looks like you have done all the right stuff so far. Based on the time that it runs, my guess (only a guess) is that the leak is at the fuel/water seperator. You should check the housing to make sure that there are no cracks. You should also check the fittings and hose clamps and hose. There may be a VERY small crack in the hose that is allowing air into the system. You may also consider just changing all the fuel hose just to be sure. Good luck, this looks like a process of elimination to find the problem.
Anthony: I think you are correct in assuming that you have some type of air leak. I believe that these engines consume about 1/2 gal of fuel per hour. If your engine dies after 30 min. this mean that you have about 1/4 gal. in the system before the air bubble gets to the injector/high pressure pump. Of course it will run longer at lower engine RPM's you are consuming less fuel. It looks like you have done all the right stuff so far. Based on the time that it runs, my guess (only a guess) is that the leak is at the fuel/water seperator. You should check the housing to make sure that there are no cracks. You should also check the fittings and hose clamps and hose. There may be a VERY small crack in the hose that is allowing air into the system. You may also consider just changing all the fuel hose just to be sure. Good luck, this looks like a process of elimination to find the problem.
Engine Dying...
I also concur that possible air in the fuel system is a good place to start. If you can temporarily eliminate the problem by bleeding at the "secondary" filter housing's bleed screw, then your problem should lie ahead of that point. I found a correctly-sized "vice-grip" type wrench with large curved jaws that allows me to tighten the fuel filter's collar much better (It's nearly impossible by hand...) and I added some thread sealant as well, and there is still a bit of wetness in the exposed threads! Check that you didn't strip the bleed screw by overtightening, then check all your fuel hoses and swivel ("banjo") fittings for wetness, check the connection at, and the tightness of, the fuel delivery valve, and scrutinize the water separator filter and it's hose connections to the tank's fuel shutoff valve, and to the fuel pump. Light diesel oil seeps quite insidiously and you should be able to see, feel, or smell any leaks in your fuel system. Fuel pumps can be easily rebuilt if necessary, but it seems to be doing it's job if you can pump it manually to bleed your fuel filter. (Can't hurt to put in a new diaphragm if you wish to so as well). One must play detective, and use the process of elimination I'm afraid...
I also concur that possible air in the fuel system is a good place to start. If you can temporarily eliminate the problem by bleeding at the "secondary" filter housing's bleed screw, then your problem should lie ahead of that point. I found a correctly-sized "vice-grip" type wrench with large curved jaws that allows me to tighten the fuel filter's collar much better (It's nearly impossible by hand...) and I added some thread sealant as well, and there is still a bit of wetness in the exposed threads! Check that you didn't strip the bleed screw by overtightening, then check all your fuel hoses and swivel ("banjo") fittings for wetness, check the connection at, and the tightness of, the fuel delivery valve, and scrutinize the water separator filter and it's hose connections to the tank's fuel shutoff valve, and to the fuel pump. Light diesel oil seeps quite insidiously and you should be able to see, feel, or smell any leaks in your fuel system. Fuel pumps can be easily rebuilt if necessary, but it seems to be doing it's job if you can pump it manually to bleed your fuel filter. (Can't hurt to put in a new diaphragm if you wish to so as well). One must play detective, and use the process of elimination I'm afraid...
George brings up a good point.
I think that the bleed screws all have nylon washers too. Just replace these while you are at it. DO NOT USE TEFLON TAPE and any of the fittings. This is one of the best ways to screw up your system. A little piece of this tape in the system and you can really foul things up. Only use joint compound on the fittings.
I think that the bleed screws all have nylon washers too. Just replace these while you are at it. DO NOT USE TEFLON TAPE and any of the fittings. This is one of the best ways to screw up your system. A little piece of this tape in the system and you can really foul things up. Only use joint compound on the fittings.
Eliminate the filter
Just to be sure, get a two litre container of diesel, and a length of fuel hose, put the hose on the inlet of the fuel pump. and bleed and start the engine on the clean fuel. If it runs longer than the 30 minutes you know that the problem is before the pump, if it fails, your problem is from the pump to the injector. Best replace the brass washers on the banjo fittings and bleed screw too! Have you cleaned or replaced the exhaust elbow? Do you have a steady flow of water from the exhaust? Good Luck!
Just to be sure, get a two litre container of diesel, and a length of fuel hose, put the hose on the inlet of the fuel pump. and bleed and start the engine on the clean fuel. If it runs longer than the 30 minutes you know that the problem is before the pump, if it fails, your problem is from the pump to the injector. Best replace the brass washers on the banjo fittings and bleed screw too! Have you cleaned or replaced the exhaust elbow? Do you have a steady flow of water from the exhaust? Good Luck!
RTV Sealant around filter housing
Thanks a bunch for all your suggestions. Would it be okay for me put some RTV sealant around the fuel filter housing attachment ring?
Thanks a bunch for all your suggestions. Would it be okay for me put some RTV sealant around the fuel filter housing attachment ring?
Fuel lines under pressure
Just a reminder that air shouldn't be getting into a line that's under pressure.
Just a reminder that air shouldn't be getting into a line that's under pressure.
Engine failure
Had the same problem when I first picked up the boat after a winter storage. The symptoms were exactly the same: I did all what you have done and all what was suggested. Finally it was fungus or algae that was "growing" in the fuel tank: it just required an anti-algae additive in the fuel tank. Has run perfect since then. Hope this helps.
Had the same problem when I first picked up the boat after a winter storage. The symptoms were exactly the same: I did all what you have done and all what was suggested. Finally it was fungus or algae that was "growing" in the fuel tank: it just required an anti-algae additive in the fuel tank. Has run perfect since then. Hope this helps.
had the same problem
hi!!Let me tell you, that's bad. But first I would have to ask you some questions; do you use the motor often? how often? how long do you leave it running, 10, 30, 45 minutes, longer? Although our boats should be move by sail power, you should use/run the motor for at least 30 minutes at 20mph (or whatever you call it). You should do that at least once a weak. If you don't, be ready to pay between $600 to $800. Finally it was something inside the engine. The engine had to be dismantled. There is a part that in spanish would be call "codo" (elbow in english, looks like an L and it's made out of steel or so)that had to be change. Our engine was 2 and a half years old. GOOD LUCK!!!
hi!!Let me tell you, that's bad. But first I would have to ask you some questions; do you use the motor often? how often? how long do you leave it running, 10, 30, 45 minutes, longer? Although our boats should be move by sail power, you should use/run the motor for at least 30 minutes at 20mph (or whatever you call it). You should do that at least once a weak. If you don't, be ready to pay between $600 to $800. Finally it was something inside the engine. The engine had to be dismantled. There is a part that in spanish would be call "codo" (elbow in english, looks like an L and it's made out of steel or so)that had to be change. Our engine was 2 and a half years old. GOOD LUCK!!!
Engine Trouble
I don't know a lot about the Yanmar engine, but it is doubtful that you could start the engine with air in the fuel lines. I had a similar problem with the engine getting hot and cutting off when running anything over 2000rpms. After checking the fuel, fuel lines, filters, etc., I finally found the problem to be a crusty buildup in the exhaust elbow and the water line leading to it. It was almost completely closed which caused the engine to run hot and cut off. Check the engine tempreture. Hope this helps.
I don't know a lot about the Yanmar engine, but it is doubtful that you could start the engine with air in the fuel lines. I had a similar problem with the engine getting hot and cutting off when running anything over 2000rpms. After checking the fuel, fuel lines, filters, etc., I finally found the problem to be a crusty buildup in the exhaust elbow and the water line leading to it. It was almost completely closed which caused the engine to run hot and cut off. Check the engine tempreture. Hope this helps.
engine overheating?
Bob, did your overtemp light come on (assuming you are unfortunate enough to have one) before the engine quit? All I have is a dummy light so I don't really know if the engine is overheating but I do know that the dummy light is not coming on. Another note the first time I had this problem the overtemp light did come on. I checked the water pump impeller and found that is was damaged and needed to be replace. After replacing the impeller I figured I licked the overtemp problem. But maybe not... hmmmm. Thanks for the input. To answer some of the other questions, I use the engine for about 30 mintues about twice a week. And reguarding the fungus, after replacing the fuel in the tank I put in some anti-fugul biocide figuring that would cover that base.
Bob, did your overtemp light come on (assuming you are unfortunate enough to have one) before the engine quit? All I have is a dummy light so I don't really know if the engine is overheating but I do know that the dummy light is not coming on. Another note the first time I had this problem the overtemp light did come on. I checked the water pump impeller and found that is was damaged and needed to be replace. After replacing the impeller I figured I licked the overtemp problem. But maybe not... hmmmm. Thanks for the input. To answer some of the other questions, I use the engine for about 30 mintues about twice a week. And reguarding the fungus, after replacing the fuel in the tank I put in some anti-fugul biocide figuring that would cover that base.
Overheating
I assumed that fungus was not a problem because you had a new fuel supply. Any good fuel-proof removable gasket sealant will do. Keep it low on the filter collar threads. The point about the condition of the exhaust elbow is also very valid - they have a definite lifespan after which they should be replaced. Yanmar recommends running your engine once every ten days, twice a week is a bit much. Note that diesels should be run under load, and not idled at low RPMs in neutral.
I assumed that fungus was not a problem because you had a new fuel supply. Any good fuel-proof removable gasket sealant will do. Keep it low on the filter collar threads. The point about the condition of the exhaust elbow is also very valid - they have a definite lifespan after which they should be replaced. Yanmar recommends running your engine once every ten days, twice a week is a bit much. Note that diesels should be run under load, and not idled at low RPMs in neutral.
check the elbow, it's in the engine.
I really don't think is anything that deals with the filter, or dirty diesel. Do you run the engine at least 30 minutes every time you use the boat at 20 mph (once a week)? If you don't, you should ask an expert to check the engine, especifically "the elbow". It may be clotted. I had the same problem and the engine was 3 years old.
I really don't think is anything that deals with the filter, or dirty diesel. Do you run the engine at least 30 minutes every time you use the boat at 20 mph (once a week)? If you don't, you should ask an expert to check the engine, especifically "the elbow". It may be clotted. I had the same problem and the engine was 3 years old.
It's fixed!! Loose banjo bolt
Thank you’all so much for your help. This weekend I inspected the fuel line from the tank to the pump and noticed a few cracks that I didn’t like. I cut the line and refit them onto the nozzles. Then when I tried to bleed the air out, the lift pump wouldn’t pump anything. So I thought maybe the lift pump needed to be replaced. So I was preparing to remove the output fuel line from the lift pump when I noticed that the input line banjo bolt was hand loose!!! I tightened it up and now I have no problems!! I motored around yesterday for an hour without problem. I guess the lesson to be learned here is to first check the obvious! Thanks again for all your help.
Thank you’all so much for your help. This weekend I inspected the fuel line from the tank to the pump and noticed a few cracks that I didn’t like. I cut the line and refit them onto the nozzles. Then when I tried to bleed the air out, the lift pump wouldn’t pump anything. So I thought maybe the lift pump needed to be replaced. So I was preparing to remove the output fuel line from the lift pump when I noticed that the input line banjo bolt was hand loose!!! I tightened it up and now I have no problems!! I motored around yesterday for an hour without problem. I guess the lesson to be learned here is to first check the obvious! Thanks again for all your help.
About the banjo bolt
Anthony, somethong to watch for: On either side of the banjo fitting is a copper washer. When they are seated (nut tightened up) they conform to the shape of the seat. Each time the nut is loosened and the banjo fitting moved the washers should be replaced because they are "one use" washers. The result may be a slow dripping of fuel (smell, mess, etc.). You can buy them for 40 cents apiece from Yanmar.
Anthony, somethong to watch for: On either side of the banjo fitting is a copper washer. When they are seated (nut tightened up) they conform to the shape of the seat. Each time the nut is loosened and the banjo fitting moved the washers should be replaced because they are "one use" washers. The result may be a slow dripping of fuel (smell, mess, etc.). You can buy them for 40 cents apiece from Yanmar.
- Status