Yanmar 2gm20 injector pressure.

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Paul06

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Hi,
As the title. After searching the web for a while, I still can't find any info on the correct release pressure for my injectors. I've got one popping at 140bar and one at 160bar. I'm hoping one of them is right and only one is wrong, not both wrong.
Does anybody know the correct pressure to set them to.
Thanks
Paul
 
Paul06 said:
Hi,
As the title. After searching the web for a while, I still can't find any info on the correct release pressure for my injectors. I've got one popping at 140bar and one at 160bar. I'm hoping one of them is right and only one is wrong, not both wrong.
Does anybody know the correct pressure to set them to.
Thanks
Paul
Click to expand...

I didn't even know that Yanmar injectors were adjustable.

I live and learn!

Richard
 
Just to answer my own question and to assist anybody else who may wish to know. I found the answer in a manual that I have. 170 kg/cm2. Or 166 bar. Both are now set to 160 bar, ready for refitting.
Thanks.
 
I've been looking for the same answer that you were so thanks for the info with the pop pressure but out out of curiosity how did you change the pressure as I've had mine checked & one is 143 bar & the other is 156 bar?

Is there shims you can change?
 
I've been looking for the same answer that you were so thanks for the info with the pop pressure but out out of curiosity how did you change the pressure as I've had mine checked & one is 143 bar & the other is 156 bar?

Is there shims you can change?
 
Just had mine tested, one is 143 bar the other is 156 bar
How did you manage to increase yours?

Did you shim the springs or just clean?
 
Thanks for the reply, there's not much information out their on these injectors that's why I thought I'd bulk it out a bit by repeating myself ;)
I'll let you know how it works out

Out of interest how was it running before & what's it like now?
 
Here is a video of the problem I was trying to fix.

https://youtu.be/wlHO7WqAWEs

As the engine (2gm20) rpm reached 3000 it developed a mis-fire. You can see me trying to identify the problem cylinder by loosening the fuel pipe to each injector in turn. Trouble is the white smoke stopped no matter which pipe I opened.
 
I take it you solved the misfire with the injector?
Mine starts on one cylinder enitially from cold but after a few seconds with increased revs the other kicks in

Also as an experiment when the engine was warm i lifted the decompression levers one at a time to see how it runs on each cylinder independent of the other & it only just ran on the rear cylinder but the front one was much better, so im hoping the injector will cuer it, i watched your compretion test, was it easy to make up the adapter i take it you used one of your injectors?
 
Yes, the misfire was caused by incorrect timing.
I think in one of my YouTube vids, I had adjusted the exhaust tappets so the valves stayed closed for longer. (Larger gap) The misfire started 250rpm later.
One of the first things I checked was the timing, on my engine the timing marks were on the front of the flywheel, Only visible after removing the starter. Two timing marks for each cylinder. The fuel pump injected fuel exactly on one of the lines, same for the other cylinder. So I looked at everything else.
Only to come back to a timing problem. I felt the fuel didn't have time to completely burn at higher rpm. Adjusting the exhaust tappers gave the fuel longer to burn, and the misfire started at a higher rpm.
Turned out the injection timing was set on the TDC line and not the before TDC line.
I removed a shim from under the injector pump and this cured the fault.
The face injector used during the compression test was just a piece of aluminium bar with a hole drilled through, then threaded at the end for the gauge.
 
Good fault finding and analysis. I wonder who had set up fuel pump timing at TDC rather than POI?

For reference both using your hartridge machine and the compression tester you can fit a 'snubber' twixt gauge and medium being measured and it smooths the pulse of the measurements making it easier to get a true reading.

Gauge snubber like this
 
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I think the problem was caused because the flywheel wasn't stamped with the "T" for TDC, also the manual I have describes the process only from the back of the flywheel, using a phrase like "to the left of the TDC timing mark T",
but with no T and working on the other side of the flywheel things get confusing, which is why I didn't spot it first time I checked it.
I bought the engine secondhand, it was too big for the boat it was in and was replaced with a new 1gm10. I imagine it was never used in anger, so the fault was never seen.
Regarding the snubber, I did borrow a compression tester kit, a hose was fitted to the gauge and the other end had a quick release coupling, similar to airline connectors.
Long story short, I only screwed the gauge onto the fake injector, the needle moved so fast you couldnt even see if, I even tried filming it and then playing it back. No joy.
I had the digital gauge handy so I used that, it stores the highest pressure seen, but even with that, the frequency was too slow so it took a while for the gauge to be looking and the TDC to coincide. You can see it happen on the video. The highest pressure jumping up untill it peaked.
Thanks for the link, I think I will get one in case I ever need to check the compression again.
 
No, I didn't have one. I did try using one of the injector pipes but it wasn't the right shape.
In the end I removed the pipes from the pump and dried the fuel from the pump output nipple and set it so that the fuel was almost level with the top, when the POI was aligned.
The whole process wasnt described very well in the manual, and i couldn't find any videos of anybody else doing the same.
With the shims that were fitted, I needed to remove one. There was a choice of 3.
One thick one and two thin ones, one slightly thicker than the other. I tried with one removed, then the other.
Not an exact science, but it has cured the fault I had.
 
Well a spill pipe just makes it a bit easier but you seem to have the measure of it.

This documents it pretty well - Linky - see page 9 of 21 Para 11.

In my experience it is worth the effort and being pedantic on getting fuel pump timing spot on.
 
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I would of liked to use a spill pipe, because the way I did it was so vague. From when delivery starts, untill when it finishes is possibly 3 or 4 degrees rotation of the flywheel. Without the spill pipe to provide a definite drip, it was all a guess, an educated guess, but all the same, a guess.
I'm pretty pleased with the results, but had I asked for advise on this great forum first, I could of got better results in a shorter time frame!
I'm not sure the link is right. It takes me to a search page rather than a manual.
 
Paul06 said:
snipped
I'm not sure the link is right. It takes me to a search page rather than a manual.
Click to expand...

How polite - I had completely bolloxed it up! I have corrected the link and tested it.

Knocking up a spill pipe is easy peasy - if you have access to the unions for freemans. Talk to the local diesel mechanics they will have a come in handy box with dozens of them sculling around.
 
Paul06 said:
Just to answer my own question and to assist anybody else who may wish to know. I found the answer in a manual that I have. 170 kg/cm2. Or 166 bar. Both are now set to 160 bar, ready for refitting.
Thanks.
Click to expand...
I have a service manual for the GM series I can't see that in the manual. I don't know if I have the same manual can you tell me what page. Thanks
Edit, found this useful site thought I'd post for future reference
https://www.manualslib.com/manual/791391/Yanmar-1gm10.html?page=103#manual
 
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