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Hi All;
I recently replaced the fuel filter and attempted to prime the system. One cylinder primed no problem, however, the rear line coming out of the injector pump won't prime. No fuel comes out with the manual lever, or when turned over with the compression levers opened. Is this a problem in the injector pump? I've looked everywhere for what could be causing this and it seems to be a unique problem. The fuel shut off appears to be fully disengaged, and the motor ran fine before changing the filter.
 

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I'm sure someone will know and help :)
 

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That would be an odd problem for a pump. Have you checked that the line isn't clogged or kinked?

By the way, same engine, same problem, different member name, from a thread on the same topic. Did you open a second one?

 

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Hi All;
I recently replaced the fuel filter and attempted to prime the system. One cylinder primed no problem, however, the rear line coming out of the injector pump won't prime. No fuel comes out with the manual lever, or when turned over with the compression levers opened. Is this a problem in the injector pump? I've looked everywhere for what could be causing this and it seems to be a unique problem. The fuel shut off appears to be fully disengaged, and the motor ran fine before changing the filter.
Ugh! I have the same problem, trouble bleeding the lines. If you look at my thread on " I think I broke my Yanmar" ,you'll see I went down a rabbit hole that lead to an even bigger problem. You should read it to make sure you don't start making the same mistakes I have. Be very careful if you take out the injector screws, I crack it in half and as of now wait on the new screws to come it. Before getting into the mess I'm in now, my problem was the primary fuel filter, it was leaking and had to be replaced. Check your lines for leaks. Minniewaska has been a great help in my plight and I feel I'm getting closer to solving my problem. Good luck La Blurr.
 

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Discussion Starter #5
Thanks for the replys;
Funny, same boat, same motor, same problem. I forgot to ad 1 detail. After changing the filter, and bleeding it out to the filter. I started the motor and it ran for a few minutes before turning off. I think air in the line might have caused some sort of air lock in the injector pump.
Since it was already necessary to bleed the lines after changing the fuel filter then running it until it shut off, I went ahead and changed the injector nozzles. That all went smoothly. Since then, and several attempts to bleed the lines using the motor with compression off, compression on, manual lever, ect. I put an electric pump between the filter and the lifting pump. Both the electric pump, and the lever push fuel out the front line at the injector at a good rate. I have managed to get a small amount of fuel out the rear line, and the motor has fired, but not stayed running. I did find a video on youtube where a guy with the 2 cylinder gm model, appears to have the same problem. He just kept cranking and the darn thing eventually started. I'm not sure I am willing to risk burning out my starter using that method just yet. I also found another video where the guy gets his 3 cylinder Yanmar to prime by squirting diesel into the intake. From my reading this is not a good idea if your motor has glow plugs/ preignition, but might be ok for the 2qm15 that has none.
My buddy with a boat on same dock is coming over in a bit and we are going to give it another whirl.
I will update results.
In the meantime I will go read your thread.
Thanks
 

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Ok, I read throught the thread. I knew about the hydro lock issue, I set my exhaust system up so this is not a problem. I have two new starting batteries, and 3 deep cycle batteries, all kept topped off with 100 watt solar panel, so thats not an issue either. I'm going to try to bleed that rear cylinder again by turning the motor over with the compression lever pulled, and try cranking it again.
 

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Ok, I read throught the thread. I knew about the hydro lock issue, I set my exhaust system up so this is not a problem. I have two new starting batteries, and 3 deep cycle batteries, all kept topped off with 100 watt solar panel, so thats not an issue either. I'm going to try to bleed that rear cylinder again by turning the motor over with the compression lever pulled, and try cranking it again.
Ok, I read throught the thread. I knew about the hydro lock issue, I set my exhaust system up so this is not a problem. I have two new starting batteries, and 3 deep cycle batteries, all kept topped off with 100 watt solar panel, so thats not an issue either. I'm going to try to bleed that rear cylinder again by turning the motor over with the compression lever pulled, and try cranking it again.
Ok, I read throught the thread. I knew about the hydro lock issue, I set my exhaust system up so this is not a problem. I have two new starting batteries, and 3 deep cycle batteries, all kept topped off with 100 watt solar panel, so thats not an issue either. I'm going to try to bleed that rear cylinder again by turning the motor over with the compression lever pulled, and try cranking it again.
My finger are crossed, please let us know how you resolve it. I'm literally in the same boat.
 

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If you didn’t get debris into the system, and you have no air leaks in the fuel connections, the fuel system will prime if you pressurize it and crack open the return line fitting from the injectors at the fuel filter (the small one on the engine) until all the air is out. Manually pumping with the fuel lift pump is a PITA and I was seldom successful using it so I installed a primer bulb in the fuel supply line near the tank. Works a treat.
 

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Discussion Starter #9
I have to head home today so I'm going to give a quick update.
As I mentioned, one cylinder primes no problem, I've bled the line at the fuel filter several times. There was no debris in the old filter when I took it out, or in the bowel. I changed the filter because in my infinite wisdom decided it was probably time to put the spare in. LOL.
No fuel comes out the rear line at the fitting coming out of the high pressure pump. I'm guessing there is an airlock in the pump from running it dry after changing the filter, and their is not bleed screw on the injector pump like in newer models. Looking around I found a rebuilt injector pump for a reasonable price, so I went ahead and ordered it, as a spare if I figure out the old one, but changing it out seems to come with it's own set of problems. It has to be put in perfectly or I will have to retime the darn thing.
I have posted my question on the Hoye tractor forum. They deal with yanmars, and sell the pumps. Their web site says these pumps don't go bad unless there is bad fuel, and I already know that is not the case.
 

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I changed the filter because in my infinite wisdom decided it was probably time to put the spare in. LOL.
Good plan. The filter manufacturers specific the amount of time the filter media can remain exposed to fuel. One year, by calendar, is what I've typically seen, with a variety of hours in use. There may be an argument the OEM's are just trying to sell filters, but it stands to reason these filters would decay eventually, while sitting in a solvent.

Their web site says these pumps don't go bad unless there is bad fuel, and I already know that is not the case.
I agree. Injector pump failures are most likely to just become timing issues and the engine still runs. OR, they fail completely. I had an internal shaft break on one and it was done. Pumping out of one line and not the other is very odd. Airlock isn't setting right with me either.

Have you removed the fuel lines from the pump itself and cranked to see whether each pumps fuel?
 

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Don't know about the 2QM, but my 3GM has a bleed connection on the injection pump. It's not mentioned in the bleed procedure in the Yanmar manual. One spring I couldn't get my engine running after changing filters until someone mentioned it.
 

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Here is the response from the yanmar forum. Running it dry more than likely caused the cam to get stuck. I've tried tapping on it, but not while it was being cranked.

It is very common for injection pumps in tractors that have water in the fuel to stick when setting or when ran out of fuel.

Why?
The injection pump has a tiny plunger on each cylinder that is spring loaded. When the cam pushes them up they squirt fuel. When the cam turn more they fall down. When there is water in the fuel or you run out of fuel completely- the cylinders can stick or 'flash' rust slightly & the ultra tight tolerances in the pump get too tight. When the plunger goes up it gets stuck and the spring is not strong enough to push it back down. The cam just spins & either does not make any contact with the plungers or just barely moves them & pumps very little fuel.

A gentle tap of a hammer on the side of the pump mounting flange while cranking the engine will frequently "un stick" the plungers & the pump will start to pump fuel again. More serious cases require the pump to be removed & rebuilt.
 

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Reads like they are saying the plunger gets stuck, not the cam. Let us know if the tap-a-tap fixes her up. Injector pumps a delicate device to be whacking too hard.

Reminds me of helping my Dad change the ball joint on our family car, when I was a kid. He had this fork-like tool that was to separate the joint from the rocker arm. We tried everything, for hours and hours, to get them apart, including heat and every form of spray witchcraft.

Finally, he calls a friend who owns a garage. His friend says to take a small sledgehammer and bash the side of the rocker arm. My Dad asks whether that could break anything, to which is friend says, if you can break it, I'll buy you a new one. Bash away.

We return to the car in the garage, one swift hammer blow and she dropped right out.
 

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Regarding Yanmar engines, I once was finishing up a rough-motion bar crossing part of the delivery on a 36 footer with a 3 cylinder Yanmar, and we were rolling enough that some air in the tank got into the line and stopped the engine. We had enough wind at the time - motor sailing - that we could wait until the water smoothed out some and then the owner started bleeding the engine with the built-in bleed screw/bolt.
Well, that bolt is hollow, and with a tiny bit too much tightening force it... broke... :(
Wind held and we sailed into the marina and pulled into an open slip without hitting anything. (!) :)
In a small town it took an extra day to find a same-thread bolt and modify it to fit so we could bleed out the Yanmar and run it again.
Than damned little metric bolt turned out to be cast aluminum, and brittle when torqued on too much.

The two cylinder might be different, but still something to keep in mind.
 

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Discussion Starter #15
Regarding Yanmar engines, I once was finishing up a rough-motion bar crossing part of the delivery on a 36 footer with a 3 cylinder Yanmar, and we were rolling enough that some air in the tank got into the line and stopped the engine. We had enough wind at the time - motor sailing - that we could wait until the water smoothed out some and then the owner started bleeding the engine with the built-in bleed screw/bolt.
Well, that bolt is hollow, and with a tiny bit too much tightening force it... broke... :(
Wind held and we sailed into the marina and pulled into an open slip without hitting anything. (!) :)
In a small town it took an extra day to find a same-thread bolt and modify it to fit so we could bleed out the Yanmar and run it again.
Than damned little metric bolt turned out to be cast aluminum, and brittle when torqued on too much.

The two cylinder might be different, but still something to keep in mind.
HA, When bleeding I found out that the aluminum bleed screw was already stripped out, or was stuck in there and when I unscrewed it stripped. That's probably why air got in the system to cause this entire episode after changing the filter.I found a suitable replacement in my sack of nuts and bolts that worked for bleeding and sealed after. I plan on drilling another one out with the drill press now that I'm back at my shop. We'll see how it works out.


In the computer world they call it the 4, 8, 12 cure. Those are the heights you progressively drop your computer from to get it working. I have had to "tap" on the starter before to get the bendix to disengage. I'm sure everyone has had to do that at one time or another on something.

I live in Vegas and My Boat is in LA, so I won't be able to get back down there until next weekend at the earliest. The new pump is supposed to be here on the 4th. I really hope I don't have to go that route. If I do I'm going to bring in professional help. There's a few good mechanics down there that will help me out if I ask. It's a big advantage having a boat in the same marina for 10 plus years, as I'm sure a lot of you know.

Here's a link to the Yanmar / Hoye tractor tech forum;
 
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