Yanmar 1GM10 delivery valve

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nickcrowhurst

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The 1GM10 in my Eventide has been laid up for three years, so I have restored the entire fuel supply system with the tank out and cleaned, new flexible lines , filter housing and both filters. Today I put 4 litres of fresh diesel in the tank and bled the fuel lines and filters using gravity and the manual pump. When I reached the top of the fuel injection pump I could get a good supply of fuel from the cross point set screw bleeder below the delivery valve, but no fuel would come out of the top of the delivery valve spring holder, UNLESS I unscrewed the spring holder one turn. I had disconnected the steel line to the injector. I tried turning the engine over by hand and by starter motor, without success.
I dismantled the delivery valve and plunger barrel. It was not stuck, and there was no dirt. The engine fuel stop lever on the injector pump was hard against the end stop.
I'm guessing that the fuel pump pressure is insufficient to open the valve against the delivery valve spring, but that's just an ignorant guess. I would have thought that the spring would have weakened over time, making bleeding easier. Perhaps more fuel in the tank would help? .In previous years the engine has bled very easily.
Any experiences of this issue? This is above my pay grade. Thanks in advance.
Nick.
 

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Fuel should only come out of delivery valve when engine is turning over, never when bleeding fuel system with engine not running. If you have bleed the injection pump then fuel should be spitting out of delivery valve when turning over on starter. It may take a few moments on starter as only a tiny amount of fuel will be pumped on each stroke. If you have disconnected the metal pipe to injector and are expecting fuel here, remember that will take longer as fuel has to travel up pipe. If you are sure all fuel system is bleed to the injector pump and you have spent couple of minutes on starter, pausing every 10 seconds or so (use decompression lever to take load of starter) and still no fuel from delivery valve you could have a jammed element or tappet inside injection pump caused by it having spent three years not being used.
 
Many thanks for your reply. Tomorrow I'll use the starter for longer periods. I disconnected the rigid pipe from the delivery valve spring holder, not from the injector.
Nick
 
Ditto the above.
Just bled a 1GM10 this afternoon. I had put a bulb pump in the delivery line before the engine driven pump and pressed that with the bleed screw on the injection pump input line banjo fitting loosened, until clear fuel came out.. Battery was a bit low, so spun her with the decompresser lifted for a few seconds and off she went.
I doubt that the delivery valve is the problem, as we are talking about 170 bar.
 
And, if loosening the delivery tube off the top of the pump. Make sure that you use a spanner to hold the valve against the force needed to release the nut. Though you seem to have had the valve out already.
I have found with these engines that bleeding as far as the pump is enough, without loosening the injection pipe.
 
As Black Mercury said, and as described in the Operation Manual, the outlet from the injection pump, with the top metal pipe removed, should spit out fuel with a strong high-pitched hiss. Yesterday I turned the starter motor over several times for 30 seconds, and no fuel emerged from the top of the injection pump. However, if the delivery valve spring holder is removed, or is slackened by a turn, the pump produces plenty of fuel through the valve. The engine was turning over very fast, with the decompression lever activated.
I've dismantled the delivery valve, and there was no dirt or jamming of the valve in the plunger barrel. For the past 30 years I've bled this engine right through to the banjo at the injector, but now I can't get any fuel through the delivery valve.
If there is a fault with the injector pump, would not the same fault stop fuel emerging from the top of the pump when the delivery valve is removed?
I'm well beyond my pay grade here.
Nick
 
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I've just found this post from 2011, and it describes my pump symptoms. Could I have a problem with a stuck fuel control rack? How should I check and fix this? Do I have to remove the injection pump? Thanks. Nick.

Bilgediver
24-04-11, 20:00
"I checked the fuel stop lever inside the timing gear box. The fuel flow doesn't look to be enough as I ran it with the fuel line to the injector disconnected from the injection pump. There was only a little trickle of fuel at very low pressure."

Was it a constant trickle or was it small spurts?????
If a constant small trickle this could indicate the pump rack is stuck in zero delivery and you are seeing fuel pressure from the priming pump finding its way through the pump. If in spurts than the pump is not stuck and maybe as the other fella said you just need to connect up the injector. There is only high pressure when the pump has to deliver through the injector holes which are very very Wee....If a big hole then no pressure.
I had a look at one of these engines. The pump is a bog standard Bosch. You can see the rack by looking through the oil filler hole. You might need a mirror.
You also would see the rack if you removed the stop lever flange.
A stuck rack would produce the symptoms you describe.
 
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Ok, you need to look through the oil filler cap you might be able to see the cam operating the injection pump. You are looking for the tappet with a roller on the base that runs on the cam. Turn the engine over by hand, you should see the tappet moving up and down. If the tappet is stuck up then the element has seized in the pump. You should also, if you can get to it, be able to move the rack a small amount. I suspect you probably can't as the pump will have seized. What you can do if you are able without removing the pump is to put the cam pointing away from the tappet and gently lever on the base of tappet with a screwdriver to try and persuade it to fall on its spring pressure. Do not try and force the rack to move, you could damage the quadrant or cause them to slip. If this fails, take off your delivery valve again completely, set to one side. Looking down into where the delivery valve was you should be looking at the top of the pumping element, refer to your diagram. With the cam still facing away from the tappet looking through the oil filler cap, you now need to very gently tap the top of the element. So get something that will fit down onto the top of the element ( small punch etc) and gently tap with something light. Do not use a hammer! The element is super hard so you won't damage it, but it will be very brittle, so go easy. Fingers crossed the element will fall down the barrel and the tappet will spring onto the cam. Put delivery valve back on and turn engine over a few times to make sure it doesn't jam again. Once engine is up and running you should be ok for another 3 years! If you can't do this on engine you will have to remove pump. It takes very little to jam an element, in fact when the element is new you are forbidden from touching the surface with bare skin, as the oils from your skin can cause the elements to jam, the tolerances are that tight. If the tappet is moving up and down with the engine turning over the rack might just be a bit sticky, and may just need manually working back and forth, if you can get to it through the filler hole. Just go carefully and methodically and you will get there!
 
Black Mercury, that's a great reply, thank you. Although I have the full service manual it doesn't cover the points you make. I'll get at it tomorrow.
Many thanks. Nick.
 
No, those points won't be in any service manual! The pump is not supposed to seize! Look down oil filler cap with strong torch and refer to your exploded diagram of pump, things will be much clearer then.
 
1gm10 injector pump.png
I followed Black Mercury's excellent guidance. The fuel control rack moves very easily with a finger touch. The cam was revolving with the starter but the tappet was hidden under the bottom of the pump. I removed the delivery valve and operated it by hand to check that the valve dropped into the seat as required. I tapped the plunger holder with a punch, and operated the starter. The plunger moved up and down about 3 mm with wide open throttle, and fuel flowed out of 3 or 4 small holes in the top of the plunger. (This differs from the Manual, which shows a square cut out on one edge.) However, the fuel emerged as if driven by the engine pump, and was not hissing and spurting. I replaced the delivery valve and, using the starter, was able to get fuel flowing through the banjo union at the injector.
I haven't attempted to start the engine, as it has almost zero compression. I'm soaking the piston rings and valves with a mixture of diesel, auto transmission fluid, and Marvel Mystery Oil (from the USA, and it looks like Redex). I set the valve clearances at 8 thou.
With this mixture injected through the air intake I immediately got good compression, so I suppose valve seats and guides are suspect. Yesterday I put the mixture into the cylinder after removing the injector, and will leave it a couple of days. After 3 years of disuse, there is contamination with the diesel bug (I treated the tank on lay-up, but not the lines. Mistake.) I feel I should have the injector serviced, as I'm not sure if it's working properly, and probably the injector pump at the same company, while deciding whether or not to have the head off.
 
After a lay up of that length, I'd automatically have both the (HP) Fuel Pump and injector serviced. Any good specialist firm should do both and check their operation before returning them to you.

I'd also replace the oil lines that run underneath the sump as a precaution.
 
After leaving that mixture down the cylinder make sure you rotate engine over with decompression lever lifted, you don't want a bent conrod at this stage. When you have fuel spitting from injector union while turning engine over, tighten union, continue to wind engine over on the decompressor, you should hear injector squeak, or feel injector fire if you put fingers on injector. If you can the injector isn't seized. Then rig up some water and go for a start. It's going to smoke for a while with remains of your mixture in cylinder and exhaust but don't worry about that. If it starts run it for half hour or so, come back when it's cold and see how it starts. If it starts easily and runs ok and idles ok, I would leave head and pump alone. You can get injector tested at some time. Remember to change oil, some of your mixture will have gone down into sump. Hopefully engine will run ok.
 
nickcrowhurst said:
Great advice, thank you. I'll update this thread when (or if) I make progress.
Nick.
Click to expand...
I've been laid up for months with pneumonia. Today I ventured outdoors for the first time, and I hope to visit my Eventide soon. Before falling ill (with a virus caught from an old gent in Paris whom I helped carry his luggage through the streets and Eurostar Customs for an hour) I had the high pressure fuel pump overhauled, including complete new inner parts, injector overhauled, cylinder head machined and new exhaust valve and seat. Then she started first time. The trickiest part was disconnecting the lever which operates the fuel control rack so as to remove and replace the high pressure fuel injection pump. As suggested, I did this through the oil filler hole, gently bending the lever sufficiently to disconnect it. The shop manual says to demolish the front of the engine. That wasn't going to happen.
I'm very grateful for all the advice, particularly from Black Mercury. I regret having been too ill to respond earlier. Without your advice I'm suspect I would have ended up by scrapping the engine.
Nick
 
Good news, glad to hear engine and yourself are recovered. As my old boss used to tell me 'its man made so it can be fixed by man'. Humans aren't, so not as easily fixed! Your health should come first. You now should have an engine with many years left in it.
 
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