Yanmar Problem

Bud22569 · Dec 19, 2009

Ysm12

I don't know if you can buy them online from Japan or not. I have a YSM12 in my boat. I have a few new crush washers. I could send you some if you told me which fittings you wanted them for. However, it will be a week or longer before I could get down to my boat to get the washers. I have heard that there is a method to bring some life back to crush washers. Perhaps someone will chime in and explain that process to you.

I have had a similiar problem in venting the fuel system. There is a method that has always worked for me, after I felt that I had adequately vented all points and the engine still would not start. Disconnect the fuel feed line at the injector. Loosen the fuel feed line at the high pressure pump and then rotate the line so that the outlet is aiming up. Then retighten the line at the high pressure pump. Use a rag to keep from making a mess. Then crank the engine. You should get a small shot of fuel each time the engine turns over when the system is properly vented. It won't shoot high and the volume will be minimal. After you feel that the high pressure pump is pumping properly, reconnect the fuel line and try to start the engine. This has worked for me several times when I just did not seem to be able to get all of the air out of the system.

Someone may see a problem with this method. However, it has saved me much frustration in the past. When my boat sits over the winter, air seems to get into the fuel system. I am getting ready to change all of the crush washers in my fuel system because of this air problem.

Let me know if this works for you and let me know if you would like for me to send you some crush washers.

Bud22569 · Dec 19, 2009

Ysm12

I really do not mind sending you the washers. It will just take time. I am sure someone here will have fast access to at least give you the measurements so that you maybe able to buy them locally. Also there is the process of bringing life back to the old ones (someone may know what this process is and if it really works).

I would think that Yanmar parts would be easy to get in Japan since that is where they are made (I think). I do not have a Yanmar dealer or distributor in my state. Yanmar has some sort of regulation that requires me to buy parts from a specific distributor. For example, Torresen in Michigan is a Yanmar dealer and they maintain an online store for Yanmar parts. However, they refuse to sell Yanmar parts to you if you do not live in a state that is in their service area. They will send you an email after your online order telling you that they can not sell you the part.

I have a parts catalogue and a repair manual for the YSM12. Let me know anytime you need information from either of these books.

Don12364 · Dec 19, 2009

It Could be This

My last boat had a Yanmar 2QM12 of about 1978 vintage and this had a problem which could also afflict the YSM12.
The injectors have a spill line to take the leakage from the injector pintles away from the engine. This leakage is normal and it is also normal to feed this fuel back to the tank.
What Yanmar did on my engine was to plumb this spill fuel back into the fuel filter.
All is well on a new engine but eventually the injectors wear a little or don't shut off quickly enough. This results in minute bubbles of cylinder gas getting into the spill line and this, of course, gets circulated back round to the injectors eventually air locking them. I noticed this first when the engine wouldn't start.
Having diagnosed the problem (after enormous troubles) I confronted the local Yanmar dealer and he knew about the problem and supplied (FOC) a banjo fitting to replace the one on the original fuel filter. This fitting had an extra outlet which I connected to a new tapping I put in the top of the fuel tank.
After which, and apart from needing to open the throttle fully to start the engine, there were no further problems.

I reason the YSM engine, being about the same vintage, could also have the same injectors and fuel line plumbing. It is easy to check visually. If so you might only need to re-plumb the spill fuel directly back to the tank and also blank off the inlet to the filter banjo.
Hope you soon find the cause.

Snotter · Dec 19, 2009

Also, try putting an electric fuel pump in. In the states, they cost from 40 to 60$ and can be bought in any autoparts store. Put aligator clips on the ends of the wires and hook it up only when you want to bleed the system. Bleeding is much more easier this way. When the fuel pump isn't hooked up, it will not hinder the existing fuel pump.

Bud22569 · Dec 19, 2009

Donalex said:
My last boat had a Yanmar 2QM12 of about 1978 vintage and this had a problem which could also afflict the YSM12.
The injectors have a spill line to take the leakage from the injector pintles away from the engine. This leakage is normal and it is also normal to feed this fuel back to the tank.
What Yanmar did on my engine was to plumb this spill fuel back into the fuel filter.
All is well on a new engine but eventually the injectors wear a little or don't shut off quickly enough. This results in minute bubbles of cylinder gas getting into the spill line and this, of course, gets circulated back round to the injectors eventually air locking them. I noticed this first when the engine wouldn't start.
Having diagnosed the problem (after enormous troubles) I confronted the local Yanmar dealer and he knew about the problem and supplied (FOC) a banjo fitting to replace the one on the original fuel filter. This fitting had an extra outlet which I connected to a new tapping I put in the top of the fuel tank.
After which, and apart from needing to open the throttle fully to start the engine, there were no further problems.

I reason the YSM engine, being about the same vintage, could also have the same injectors and fuel line plumbing. It is easy to check visually. If so you might only need to re-plumb the spill fuel directly back to the tank and also blank off the inlet to the filter banjo.
Hope you soon find the cause.

Your description matches my YSM12. The injector return line goes back to the Yanmar filter only. Thanks for the information. I never thought about this as a potential for getting air (gas) into the fuel system.

Ed Schenck · Dec 19, 2009

Another possibly inexpensive test is to use an outboard fuel tank, the kind with the squeeze bulb. Cut off the end that connects to the outboard motor. Clamp the hose right on the input to the filter. Squeeze the bulb until it is hard. With this pressure I did not even have to bleed my old 2QM20. It would start every time. If this doesn't work you almost certainly have your injector pump out of time.

I carried two gallons of diesel in that tank in a locker for years as backup.

Jonrod222 · Dec 19, 2009

If the washers are copper, you can take a small torch and heat them up, it softens them so you can use them again. I have done this on solid copper head gaskets on older cars that parts were no longer available.

sailaway78 · Dec 19, 2009

Bleeding injectors

You must also bleed the lines between the high pressure pump and the injector. If there is any air there, it will compress and will not open the injector and the engine WILL NOT fire. This is a pretty easy issue to deal with. Simply loosen the fuel line at the injector, open the compression release, open the throttle wide open and spin the engine over with the starter for a few seconds.

Steve C. · Dec 19, 2009

remo7e, you can take a some sand paper 100 grit put it on a flat surface and sand the copper washer until the surface is shinny and flat, that should work. I have done this many times. The washer is a little hard to hold but it works. Do not heat them. Volvo Vw and most german cars used them in the 80's, so you should be able to find them.

Hermit Scott · Dec 19, 2009

remo7e said:
I'm at the end of my rope trying to figure out why my YSM12 won't fire. I think it is either air in the lines (yes, I've bled them to death), timing is off, or a bad injector pump.

I'm living in Japan, so I can't just run down to a local parts store and get things easily (and certainly not cheaply).

I'd like to replace the crush washers. Can anyone tell me what size I need and if this is something I can order online?

Those copper washers are pennies to us in the US. How much more could it be for you? What prices are they if you order them by mail? I have the parts catalog and the manual to the YSM12 and I am farmiliar with the engine. You need to have new washers to elimnate the possiblitiy that that is where your air leaks are coming from.
Shipping is going to be much more than the cost of those parts unless you are having them sent to you from Japan. But shipping is not that much for parts that weigh less than an ounce.
If you keep running your engine you will inevitably need some parts to fix or maintain it. You really need to have a source for those parts. What would you do if you blew a headgasket? Some things are so specific that you must have the part from yanmar, but something as ubiquitous as a copper washer giving you trouble, shouldn't be the case.

DougM · Dec 19, 2009

Look at your fuel lines... If they are old the rubber may have some fine cracks that are not apparent with just a quick visual inspection. These fine cracks are just enough to let air into the system, yet don't show any signs of fuel leakage. A friend of mine discovered this on his boat ater replacing just about everything else in the fuel delivery system.

RAD88 · Dec 19, 2009

One quick trick that helped me in the past is - remove the vent line from the tank and blow air through it. If the vent line is clogged with salt it will create a vacuum in the tank and hinder starting. Sounds too simple to be true but it worked on m boat. Worth a try.

Cayennita · Dec 20, 2009

I have a 3GMD, but my problem was that NO fuel was getting to the injectors. The mechanic said I needed a new fuel pump so between parts and labor I spent $1300. The actual problem was that the slide under the pump that cuts off the fuel when killing the engine was stuck. Even though the cable was pushed in, the slide was open. Had the mechanic opened the side plate and inspected the mechanism, I would have spent only one hour worth of salary. Make sure and check this if there is no fuel getting to the injector(s).

Paul F · Dec 20, 2009

Agree with everything that has been said. I also had a very hard to start Yanmar 2QM15 after the fuel pump went and replaced with an electric fuel pump. This is what I would recommend. As was said, 1.) make a vent line from the top of the injector returning to the fuel tank not the secondary fuel filter. Keep the line above the engine. 2.) make up a remote starter switch to use at the engine. Run a wire from the main battery switch to the engine starter with an on/off switch in the middle. 3.) Bleed the air out at the secondary fuel filter. 4.) Bleed the air out after the injector pump. (need to turn the engine over use remote starter) 5.) open the fuel line at the injector and observe "pulsing jets" of fuel coming out. (need to turn the engine over use remote starter) 6.) Place the fuel line into the injector - run the starter and tighten the fuel line injector connection. During all of this the throttle is full open. Diesel engines need fuel, air and exhaust to work. If you have all three the engine should run.

SamLust · Dec 21, 2009

Your "crush washers" are "COMMON PARTS". They are 6 mm, 8 mm,and 10 mm. I f you can not find a yanmar dealer in Japan (where Yanmars are made) you certainly can find a Honda, Yamaha, Kawasaki, or Suzuki motorcycle shop. Washers like these arer used all over these Japanese bikes. Master cyl. banjo bolt, engine oil feed banjo bolt and so-on. Any decent parts guy will be happy to help you out. Yoy don't even need to speak Japanese. Take the part with you, he'll match it. On all but the injector I use nylon washers. They last for ever. Injectors still want copper. I once taught a Japanese technician how to rebuild and fine tine a piece of printing equipment without a word of English or Japanese.

Barnacle Bill · Dec 21, 2009

That's interesting. When I haven't been able to get Yanmar parts in the states, I have always been able to get them in Japan where they are manufactured. Hmmm.

Cayennita · Dec 31, 2009

Any diesel injector pump repair facility including for trucks will have the rings. Truck engines and boat engines all use the same rings. Maybe they will be cheaper there. I had my Perkins 4-236 injector pump rebuilt and tested at a facility in the Dominican Republic that had nothing to do with boats.