My Beloved Yanmar YSE12 - advice please - fuel issue?

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mikenfi

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Hi there,

It has been sometime since I last posted. I am looking for some advice with my Yanmar YSE12. This is the second occasion I have had it out of the boat in 5 or so years. The last time I was a new boat owner and I rebuilt it to include a new head. piston, piston rings, exhaust elbow, bearings, all gaskets and pretty much everything except the injector, although I did buy one, then found a spare fully packaged stowed away and the old one was still working fine So I kept this.

In the last month or so I went through the full service 100 -500 hours. Lifted the engine out lapped the valves cleaned everything changed the oil, and put the it all back together, dropped it in the boat, attached everything up. I have bled the fuel through checked that it pumps. It does attached to the injector, Bled the fuel again. Went through all my normal start up procedures and she turns but no ignition.

So I think its the fuel. I remove the injector and plug it up for a test to inspect the the fuel spray as per the instructions. I turn the engine and no spray. I then detach the fuel injector and turn the engine and fuel does spert out of the pipe. So Is the injector not working?

I get the other injector which is new, I pop this in, bleed and go through start procedures. I attempt to start it turns and all sounds as if it should go but it wont combust.

Thought I would try it with a bit of easy start and she nearly went but alas still no... From what I can understand if the easy start will combust and the diesel is spraying out of the injector as it should then the engine should keep running right? Am I correct in assuming it a fuel issue,not getting enough or?
 
If it does not go with easystart, I suspect the compression. But not getting the injector to spray is problematical. Maybe you need to try again with bleeding through the injector. Spurting out of the pipe does not mean all the air is out of the system? Otherwise, it sounds like you have done things OK. Since you had the whole donk out, go back on on all the fuel connections and re-bleed it .
 
It sounds as if you do not have enough fuel pressure to open the injector but enough to allow fuel to exit the feed when the injector is removed.

I would guess that the most likely reason for this is, indeed, air somewhere in the fuel line.

Richard
 
Thank you both so much for getting back to me I am pulling my hair out once again!

Now you have both mentioned it I am thinking perhaps there is air in the return pipe on the back of the injector. I guess that is where the fuel is going. I dont have the correct pressure so for the injector to spray as you say. I will insure I have primed this and bled out all the air out of the system when I take up the tools again tomorrow.

How do i ensure I get the pressure up in the return pipe? I guess bleed it in to the pump so its gushing, then turn the engine by hand with the fuel cap off the tank to force the pipe full until the injector engages?

I am struggling with it being the compression as its has a new head gasket. the head is 5 years old looked like new a very small amount of corrosion on the valves which came away nice and easy. I had the 2 stage lapping compound, cleaned everything with acetone.

I am confident that I did this correctly and I am also confident I did not correctly bleed the return fuel pipe and there was certainly air in the system.

Fingers Crossed! I will update tomorrow.
 
If it is the return pipe from the injector, that has no pressure. It just gets the leak off fuel back to the tank. You prob is very likely to be some air, or an air leak in the fuel supply from the lift pump to the injector pump to the injector. Try all the previous with the injector connected, but out of the head, so you can see the spray pattern. Just keep your skin away from the spray..
Since the engine ran before you did your service, one expects it is relatively simple, just not spotted?
 
Sweet that cleared that up regarding the return pipe. After reading the the instructions again just now. I will go though the process to the T tomorow. I have not done so today because I was complaicent andI thought I knew it all after doing it once before. I did not bleed all the air correclty! Wasted a day! but I learnt that my arogance is still in control!

Thanks again for you help!
 
Hi Mike . Another YSE 12 lover, here.
You said "I get the other injector which is new, I pop this in, bleed and go through start procedures. I attempt to start it turns and all sounds as if it should go but it wont combust. "
Does that mean that you had a clean spry pattern with the other injector?

I am a bit thrown that she won't start with "Eaststart", but will make a suggestion anyway.
I would readjust the governor /fuel supply linkage.
This solved a starting problem for me and it only takes 5 minutes, so worth a try.
The instructions for this process in the manual are confusing so I have redone it.
Here it is
gary
 

Attachments

I will adjust the govenor as well. Off to the boatthouse to get some copper washers this morning and I will going through it today will keep you updated.

I'm very hopefully it's only fuel. Seems that way I remember the sound it made before I replaced the head which was bad compression it is not sounding like that... it sounds like no fuel to combust,l.. am very sure I didn't bleed it correctly... Crossing my figures,
 
garymalmgren said:
Hi Mike . Another YSE 12 lover, here.
You said "I get the other injector which is new, I pop this in, bleed and go through start procedures. I attempt to start it turns and all sounds as if it should go but it wont combust. "
Does that mean that you had a clean spry pattern with the other injector?

I am a bit thrown that she won't start with "Eaststart", but will make a suggestion anyway.
I would readjust the governor /fuel supply linkage.
This solved a starting problem for me and it only takes 5 minutes, so worth a try.
The instructions for this process in the manual are confusing so I have redone it.
Here it is
gary
Click to expand...

Thanks for the improvement, Gary!!! :-)
 
garymalmgren said:
Hi Mike . Another YSE 12 lover, here.
You said "I get the other injector which is new, I pop this in, bleed and go through start procedures. I attempt to start it turns and all sounds as if it should go but it wont combust. "
Does that mean that you had a clean spry pattern with the other injector?

I am a bit thrown that she won't start with "Eaststart", but will make a suggestion anyway.
I would readjust the governor /fuel supply linkage.
This solved a starting problem for me and it only takes 5 minutes, so worth a try.
The instructions for this process in the manual are confusing so I have redone it.
Here it is
gary
Click to expand...

Hello again Gary! Would it be OK for you if I share your improved adjustment procedure in a Swedish sailing forum, with reference to you (your name and this forum)? Best regards, Jorgen
 
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