The YSM 12 in my Hunter 30 has developed a bit of a starting problem. Once it catches it idles very slowly, barely running, for maybe 30 seconds, then picks up speed to a normal idle. It is unresponsive to throttle during this 30 second period, then performs normally after it gets going. Once it's fully started it performs normally, full power, no problem. It happens after sitting for several days, or even after a brief 2 hour shutdown while sailing. Oddly this began suddenly, and coincided with an oil change. That must be coincidence. Anyone ever seen a diesel start like this? Thanks...
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Bill O'Donovan
Gasping for air
It could be gasping for air, which suggests the mixing elbow is clogged and needs to be replaced. At some point, the engine simply won't turn over. The only way to check this is to remove the elbow to see if it's coked up with rust and exhaust soot. A modest $150 replacement job, but it's labor-intensive. See the Archives for much on this. Or it could be a fuel problem, which is entirely different.
It could be gasping for air, which suggests the mixing elbow is clogged and needs to be replaced. At some point, the engine simply won't turn over. The only way to check this is to remove the elbow to see if it's coked up with rust and exhaust soot. A modest $150 replacement job, but it's labor-intensive. See the Archives for much on this. Or it could be a fuel problem, which is entirely different.
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John
did you change your gas filter?
I'm no pro but maybe a loose conection that lets air into your fuel line and the when engine is up to speed it begins sukin enough fuel and acts normaly. I might put in a fresh filter and tighten my fuel lines.
I'm no pro but maybe a loose conection that lets air into your fuel line and the when engine is up to speed it begins sukin enough fuel and acts normaly. I might put in a fresh filter and tighten my fuel lines.
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John Thomas
No new fuel filter
I last changed the fuel filter about 6 months ago. And it was a bugger to bleed out the air. I'll check to see if all is tight still. Thanks. RE the exhaust elbow. I had the motor in the shop a couple years ago at a Yanmar specialist to have the gear rebuilt. They also checked everything out and did find a couple of minor things which they fixed. So I'm assuming the elbow is still clean and not worth all the bother to check. Besides this came on very suddenly. I like the leaky fuel line theory and will report back. Thanks
I last changed the fuel filter about 6 months ago. And it was a bugger to bleed out the air. I'll check to see if all is tight still. Thanks. RE the exhaust elbow. I had the motor in the shop a couple years ago at a Yanmar specialist to have the gear rebuilt. They also checked everything out and did find a couple of minor things which they fixed. So I'm assuming the elbow is still clean and not worth all the bother to check. Besides this came on very suddenly. I like the leaky fuel line theory and will report back. Thanks
I thought that was the nature of the beast.
John: My friends YSM does not start very easy either. He usually opens the throttle at least half way. Then as he is cranking he pump the throttle. He leaves the throttle open until the engine really starts reving, and then moves the throttle back to a position to warm the engine. His usually does good once it has been started for the day. My guess that yours may have to do with a leak down of the fuel. You may want to consider changing the fuel lines. You may have a small leak that is not seaping fuel but leaking a little air into the system. Have you had the engine professionally serviced? It may be worth a few buck to have a pro check it out. They usually require a valve adjustment every few hundred hours.
John: My friends YSM does not start very easy either. He usually opens the throttle at least half way. Then as he is cranking he pump the throttle. He leaves the throttle open until the engine really starts reving, and then moves the throttle back to a position to warm the engine. His usually does good once it has been started for the day. My guess that yours may have to do with a leak down of the fuel. You may want to consider changing the fuel lines. You may have a small leak that is not seaping fuel but leaking a little air into the system. Have you had the engine professionally serviced? It may be worth a few buck to have a pro check it out. They usually require a valve adjustment every few hundred hours.
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Jon Petersen
I think it is air
I think Steve is right...You may have a small leak that is not seaping fuel but leaking a little air into the system. I had the same problem, but then I installed an electic fuel pump.. Turned it on with the key.. waitted 30 sec with full throttle, then start the engine.. starts right up... s/v Nonlinear
I think Steve is right...You may have a small leak that is not seaping fuel but leaking a little air into the system. I had the same problem, but then I installed an electic fuel pump.. Turned it on with the key.. waitted 30 sec with full throttle, then start the engine.. starts right up... s/v Nonlinear
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CTimmons
Exhaust Elbow
I have a 1979 Hunter 33 w/ a Yanmar 2qm15. Have had a bit of a saga this season, which started with a botched fuel filter service. When the dock monkey (employee of ex-charter club) blead the system, he loosened the pressure valve where the fuel lines exit the injector pump. Turned out I was running on one cyl. Once this was fixed, I started having similar symptoms as you report. Ultimately she stopped running at low rpms. Just yesterday I had the local Yanmar distributor out. They identified three possible causes. 1, clogged exhaust elbow; 2, wrong fuel filter in Racor (had too fine a filter for the engine); and 3, low compression (Yanmar specs 360 and I had 300 in one cyl and 320 in the other. After threatening the need for either a valve job or rebuild to cure the low compression, they replaced the elbow and fuel filters. She is now running fine under load at idle. Take the prior recommendation and check your exhaust. Do it yourself though, because a full day's labor at marine mechanics rates and parts, it set me back almost a grand.
I have a 1979 Hunter 33 w/ a Yanmar 2qm15. Have had a bit of a saga this season, which started with a botched fuel filter service. When the dock monkey (employee of ex-charter club) blead the system, he loosened the pressure valve where the fuel lines exit the injector pump. Turned out I was running on one cyl. Once this was fixed, I started having similar symptoms as you report. Ultimately she stopped running at low rpms. Just yesterday I had the local Yanmar distributor out. They identified three possible causes. 1, clogged exhaust elbow; 2, wrong fuel filter in Racor (had too fine a filter for the engine); and 3, low compression (Yanmar specs 360 and I had 300 in one cyl and 320 in the other. After threatening the need for either a valve job or rebuild to cure the low compression, they replaced the elbow and fuel filters. She is now running fine under load at idle. Take the prior recommendation and check your exhaust. Do it yourself though, because a full day's labor at marine mechanics rates and parts, it set me back almost a grand.
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Mike
I vote for air...
seeping in to system. I had a similar problem with same results. Found a slightly loose bleeder screw. 1/4 turn fixed the problem.
seeping in to system. I had a similar problem with same results. Found a slightly loose bleeder screw. 1/4 turn fixed the problem.
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Jim
Governor?
The lock nut and then the screw loosened on my governor. This came on suddenly, starting was quite difficult and the engine wouldn't idle. When the governor was properly repositioned and the screw and nut secured all was fine. You might check this out.
The lock nut and then the screw loosened on my governor. This came on suddenly, starting was quite difficult and the engine wouldn't idle. When the governor was properly repositioned and the screw and nut secured all was fine. You might check this out.
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Ian Sanderson
79 YSM12 hard starting
This spring the engine took longer and longer to start, though, once it was running, seemed fine. One Sunday morning about a month ago it decided not to start while we were 35 miles from home. After considerable head-scratching, I decided to remove the fuel injection pump and the injector from the engine and have them checked. When the re-builders sent it back fully re-furbished, they sent a note expressing amazement that the engine had been able to run at all with the pump in such a condition. The pump, it turns out, was worn so badly that it just couldn't provide enough fuel to make it go anymore. The injector, which I had replaced a year or so ago, was fine. After I re-installed the pump and injector and got the air out of the fuel lines, it started and ran better and more smoothly than I can remember. (I realize it's a stretch to use the word "smoothly" in the same sentence as "YSM 12", but the improvement was remarkable just the same.
This spring the engine took longer and longer to start, though, once it was running, seemed fine. One Sunday morning about a month ago it decided not to start while we were 35 miles from home. After considerable head-scratching, I decided to remove the fuel injection pump and the injector from the engine and have them checked. When the re-builders sent it back fully re-furbished, they sent a note expressing amazement that the engine had been able to run at all with the pump in such a condition. The pump, it turns out, was worn so badly that it just couldn't provide enough fuel to make it go anymore. The injector, which I had replaced a year or so ago, was fine. After I re-installed the pump and injector and got the air out of the fuel lines, it started and ran better and more smoothly than I can remember. (I realize it's a stretch to use the word "smoothly" in the same sentence as "YSM 12", but the improvement was remarkable just the same.
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