I have a 1978 Hunter 30 with a Yanmar YSB 12 engine. I just bought the boat and had the engine gone through, with all wearable parts (belts, hoses, etc.) replaced. On our sea trials the engine quit after a couple of hours, then started after twiddling with the fuel pump, then quit again. The fuel pump was pretty weak (barely ticking when the ignition was on,) so I replaced it after this trip. The new pump is much stronger and sounds fine, but our first trip out after the new pump was installed -- same thing, stalled after about 15 minutes. The float bowl in the Racor filter (with new element) is clear, and all hoses were replaced and are double-clamped so they all appear to be air tight. Any other ideas? I don't want to just replace parts, I'd rather trouble-shoot, but the engine manual wasn't much help. Thanks in advance! Casey
I can't keep my engine running...
- Thread starter Casey F
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Fuel line
Check your fuel line. Remove the fuel line at the Racor and blow back into the tank. There should not be any restriction, none at all you should blow bubbles in the fuel easily. I just had a similar problem with my engine and it turned out to be a clogged fitting on the fuel tank.
Check your fuel line. Remove the fuel line at the Racor and blow back into the tank. There should not be any restriction, none at all you should blow bubbles in the fuel easily. I just had a similar problem with my engine and it turned out to be a clogged fitting on the fuel tank.
Try a Yanmar Board
Casey - Check out a Yanmar / Diesel specific board....these guys are very good with this stuff and you can buy any needed parts from them too: Torresen http://forums.torresen.com/sailing/index.php?sid=7084fc6707f17fbdbba990e1f4166506 And of course try the reccos here and see if that helps. Rob
Casey - Check out a Yanmar / Diesel specific board....these guys are very good with this stuff and you can buy any needed parts from them too: Torresen http://forums.torresen.com/sailing/index.php?sid=7084fc6707f17fbdbba990e1f4166506 And of course try the reccos here and see if that helps. Rob
I like the vent idea.
Casey: I like checking the vent idea. Those engine use very little fuel so it is not unreasonable to think that some bugs have plugged up the vent line. I would also suggest that if you don't find anything else you call Bill Ingle @ Bill's Marine 510/708-9391. He is a good guy.
Casey: I like checking the vent idea. Those engine use very little fuel so it is not unreasonable to think that some bugs have plugged up the vent line. I would also suggest that if you don't find anything else you call Bill Ingle @ Bill's Marine 510/708-9391. He is a good guy.
Air leak in fuel line??
I fought a similar problem for almost a full season on the same engine. Turned out to be the NAPA-brand seconday filter element I was using was just a hair longer than the Yanmar, and there was a small air leak. I added a fuel primer bulb between the primary and secondary filters to facilitate bleeding the system, and I could squeeze that a few times to keep the engine going in a pinch. I'd check the bleed screws and the filters to make sure there is no air seeping in. That little motor will run about 15-20 minutes on just what is in the secondary and the fuel lines, so it takes a while for the problem to crop up. Usually it will run long enough to convince you it will be fine, until you cast off and get into a tight channel, with a cross-wind, and lots of traffic....... Good luck.
I fought a similar problem for almost a full season on the same engine. Turned out to be the NAPA-brand seconday filter element I was using was just a hair longer than the Yanmar, and there was a small air leak. I added a fuel primer bulb between the primary and secondary filters to facilitate bleeding the system, and I could squeeze that a few times to keep the engine going in a pinch. I'd check the bleed screws and the filters to make sure there is no air seeping in. That little motor will run about 15-20 minutes on just what is in the secondary and the fuel lines, so it takes a while for the problem to crop up. Usually it will run long enough to convince you it will be fine, until you cast off and get into a tight channel, with a cross-wind, and lots of traffic....... Good luck.
Fuel tank vent
My first vote would go to the tank vent. Thats also the easiest to check. Two hours should be long enough to build up a small vacum in the tank. I would think that a fuel line sucking air would show up much quicker. I have two large Wix fuel filters, and if I allow air into the system before the first filter, the engine will run ten or fifteen minutes, with no load before it quits. Next would be to check the screen on the pickup in the tank. It is obviously getting some fuel delivery early. A pickup screen that is stopped up will quite often loosen up some when the engine is shut off. Then when it is again running and sucking fuel the stoppage will continue to tighten up to the point it will allow no fuel at all to get by.
My first vote would go to the tank vent. Thats also the easiest to check. Two hours should be long enough to build up a small vacum in the tank. I would think that a fuel line sucking air would show up much quicker. I have two large Wix fuel filters, and if I allow air into the system before the first filter, the engine will run ten or fifteen minutes, with no load before it quits. Next would be to check the screen on the pickup in the tank. It is obviously getting some fuel delivery early. A pickup screen that is stopped up will quite often loosen up some when the engine is shut off. Then when it is again running and sucking fuel the stoppage will continue to tighten up to the point it will allow no fuel at all to get by.
engine problem
A diesel enging only needs 2 elements in order to operate...1. fuel, 2. air. It seems that you have addressed the fuel issue. Many sailors forget about the intake air screen or filter. If it's a filter change the element. If its a screen, soak it in kerosene to clean. Bob
A diesel enging only needs 2 elements in order to operate...1. fuel, 2. air. It seems that you have addressed the fuel issue. Many sailors forget about the intake air screen or filter. If it's a filter change the element. If its a screen, soak it in kerosene to clean. Bob
Symptoms and diagnosis
I'm assuming there are no other symptoms than just the engine quiting. Not smoke or funny sounds or shaking. A restriction in the air intake or exhause will cause black smoke so I'm thinking that that is not the problem. The symptoms are pointing to lack of fuel. Since it runs fine the injectors and pumps are most likely OK. since you have clean filters the only other thing is a vacume in the tank (vent) or a cloged pickup. A quick check for the vent is to take off the fuel cap (put a rag in it to keep dirt and bird poop out) and see if that fixes the problem. If so it is certianly the vent. Also if you can reproduce the problem and then quickly take the cap off note if air rushes in. Blowing in the pickup tube is the only way short of tearing into the tank to check the pickup tube.
I'm assuming there are no other symptoms than just the engine quiting. Not smoke or funny sounds or shaking. A restriction in the air intake or exhause will cause black smoke so I'm thinking that that is not the problem. The symptoms are pointing to lack of fuel. Since it runs fine the injectors and pumps are most likely OK. since you have clean filters the only other thing is a vacume in the tank (vent) or a cloged pickup. A quick check for the vent is to take off the fuel cap (put a rag in it to keep dirt and bird poop out) and see if that fixes the problem. If so it is certianly the vent. Also if you can reproduce the problem and then quickly take the cap off note if air rushes in. Blowing in the pickup tube is the only way short of tearing into the tank to check the pickup tube.
ysm12
I have a 78 Hunter 30 w a YSM12. My first trip out, after a few mins, it stalled. Turned out to be the mixing elbow was coked up. Also on the YSM12, don't know about the SB8 but theres a design flaw thats mentioned by Torrensen's Diesel Marine. Be sure your oil level is just a little below the full mark on the dip stick. If its to the full mark or above you or I will on mine start to burn lube oil and things get a little hairy from then on.. won't run right.
I have a 78 Hunter 30 w a YSM12. My first trip out, after a few mins, it stalled. Turned out to be the mixing elbow was coked up. Also on the YSM12, don't know about the SB8 but theres a design flaw thats mentioned by Torrensen's Diesel Marine. Be sure your oil level is just a little below the full mark on the dip stick. If its to the full mark or above you or I will on mine start to burn lube oil and things get a little hairy from then on.. won't run right.
Mixing elbow
I would eliminate the mixing elbow from my troubleshooting list. This is something that is slowly restricting the fuel flow. A coked up exhaust manifold will show it's symptoms long before two hours. So will I think, an air leak in the fuel system. Also if you have an air leak in the fuel system that is bad enough to cause the engine to shut down, I can assure you it will not restart without bleeding the system. Use common sense before you start tearing things apart. Anything that is a major fuel problem, will show itself early on. Think some kind of slow restriction, that will take some time for it to show up. You burn less than half gallon an hour, so think of it in those terms. Also keep in mind that after shutting it off for a while, it will start back up and run for a while. Eliminate the things that would obviously cause the engine to stall more quickly. Many of us on this board, including myself, have a tendency to start at the wrong end, and look to the more complicated things first. On these small diesels 90% of the time, it will be something very simple, and right in front of our eyes, we just don't think simple.
I would eliminate the mixing elbow from my troubleshooting list. This is something that is slowly restricting the fuel flow. A coked up exhaust manifold will show it's symptoms long before two hours. So will I think, an air leak in the fuel system. Also if you have an air leak in the fuel system that is bad enough to cause the engine to shut down, I can assure you it will not restart without bleeding the system. Use common sense before you start tearing things apart. Anything that is a major fuel problem, will show itself early on. Think some kind of slow restriction, that will take some time for it to show up. You burn less than half gallon an hour, so think of it in those terms. Also keep in mind that after shutting it off for a while, it will start back up and run for a while. Eliminate the things that would obviously cause the engine to stall more quickly. Many of us on this board, including myself, have a tendency to start at the wrong end, and look to the more complicated things first. On these small diesels 90% of the time, it will be something very simple, and right in front of our eyes, we just don't think simple.
Nice 'n Easy. All Due Respects...*sry
... but the mixing elbow will show it's malady over a period of time, mine did. But when it came down to a failure, it happened suddenly. The engine slowly and over the years that I had it, emitted grey smoke until it finally caught up to the clogging point. The new owner who previously posted here doesn't know of the existing problem. But it is bound to happen unless the elbow is new and he can tell that. Also, consider the age of the engine. Only then would I remove it from the "trouble list".
... but the mixing elbow will show it's malady over a period of time, mine did. But when it came down to a failure, it happened suddenly. The engine slowly and over the years that I had it, emitted grey smoke until it finally caught up to the clogging point. The new owner who previously posted here doesn't know of the existing problem. But it is bound to happen unless the elbow is new and he can tell that. Also, consider the age of the engine. Only then would I remove it from the "trouble list".
Casey? Racor?
The filter bowl that you speak of is a water spearation bowl. Don't confuse it with the filtration system. Since racors filter fuel from the inside-out, any reside will be found on the inside of the filter element. The bowl will simply show if there was water filtered out of the fuel and provides a way to drain the water. The bowl fuel will always be clear. I found this out last year when I changed mine. So, you probably did right by replacing the fuel pump, anyway!
The filter bowl that you speak of is a water spearation bowl. Don't confuse it with the filtration system. Since racors filter fuel from the inside-out, any reside will be found on the inside of the filter element. The bowl will simply show if there was water filtered out of the fuel and provides a way to drain the water. The bowl fuel will always be clear. I found this out last year when I changed mine. So, you probably did right by replacing the fuel pump, anyway!
Mixing elbow
Paul, From what I read and what you said, I would still agrue against it being the mixing elbow. His post stated the motor was running fine till it quit. You stated yours manifested itself over a long period of time. You also stated you had smoking for a period of time. What he is looking for is something that slowly shuts off the fuel supply. At least from what I read, there was no sign of any problem which would indicate a exhaust. They also have a tendency to run hot if the manifold is clogged. I am not saying that can't be the problem only that it should be for now, eliminated as a possible problem. It is possible the filter could be clogged up, but two hours on a new filter would take a really nasty tank, as he probably had used less than a gallon of fuel. Might be water, as he stated the bowl is clear, and if he bought marine diesel, it has a dye in it. But I kind of doubt that if there was enough water in it to kill the engine, that it would restart. Same goes for air. I can guarantee you that if you get enough air into the system to kill the engine, there is no way it will restart without bleeding the pump.
Paul, From what I read and what you said, I would still agrue against it being the mixing elbow. His post stated the motor was running fine till it quit. You stated yours manifested itself over a long period of time. You also stated you had smoking for a period of time. What he is looking for is something that slowly shuts off the fuel supply. At least from what I read, there was no sign of any problem which would indicate a exhaust. They also have a tendency to run hot if the manifold is clogged. I am not saying that can't be the problem only that it should be for now, eliminated as a possible problem. It is possible the filter could be clogged up, but two hours on a new filter would take a really nasty tank, as he probably had used less than a gallon of fuel. Might be water, as he stated the bowl is clear, and if he bought marine diesel, it has a dye in it. But I kind of doubt that if there was enough water in it to kill the engine, that it would restart. Same goes for air. I can guarantee you that if you get enough air into the system to kill the engine, there is no way it will restart without bleeding the pump.
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