Any tricks for bleeding the high pressure side of Yanmar 2GM20?

[dralex]

I've found lots of posts for the low pressure side, but am OK with that. I know the fuel is all the way through to the high pressure pump, but i'm struggling to get the engine started. I've tried loossening the nuts on the outlet side of the HP pump and turning the engine over as suggested in the manual. There is fuel coming from the aft outlet, but not the forward one. I'm getting really frustrated as i've done it by the book so far. Do you have to bleed the other ene of the HP fuel lines, before they go into the injectors?

The only thing I've not managed to do is to tighten the HP pump outlet nuts while the engine is turning over as the starter switch is in the cockpit.

Any suggestions before I spend money. Thanks.

 

[spannerman]

Normally if you want to bleed the high pressure side on a diesel you do it at the injectors as then you have eliminated all of the air from the injector pipes. Yanmars are not as easy to bleed as other makes, you have to be absolutely sure you have no air in the low pressure side, as the slightest amount will stop the engine from starting, whereas Volvo and Mercruiser seem to be able to tolerate some and you can crank it through, not so with Yanmars.

 

[steve28]

It may aid you to do this with the throttle wide open, this way allows more fuel through.
When i did mine i used a large conductor between the soleniod wire(white) and the main positive battery feed, this enabled me to crank the engine over whilst in the bay.
Dont forget to turn the water off on the seacock if your afloat.


steve

 

[RMA]

Once you have bled the low pressure side, the Yanmar manual tells you to -
1 Loosen the fitting nut on the injector just enough to expel fuel
2 Move the throttle to the full throttle position
3 Operate the decompression lever
4 Operate starter until fuel flows from the injector pipe (maximum 30 seconds)
5 Tighten the injector nuts to 15Nm
This should do it.

 

[MarkJohnson12345]

I can only add that on my Bukh 20 recently after changing the fuel filter, final bleeding was done by loosening the nuts on the injectors are turning the engine over until fuel squirts out.

Did this on each cylinder (2). And then did it again as more air came through from the filter.

Injectors are easy to get at on the Bukh.

Hope that helps

 

[jimboaw]

Yup, crack open the injectors. My old 3cyl would start on one cylinder and than the other 2 would come on line without further ado.Have plenty of paper towels around!! /forums/images/graemlins/smile.gif

 

[dralex]

Thanks for the replies- I-ll try bleeding at the injectors.

Cheers

Alex

 

[pandos]

I bleed my perkins at the injectors with the vacum bottle for extracting the oil. No trouble no mess, also great after changing filters to get all air out of low pressure side.

Not sure if this will help.

 

[andrewbarker]

Agree with all the posts which say slacken 1 injector union & use WOT. What we used to do on difficult truck engines was also to squirt WD40 or any other combustible into the air inlet & turn the engine over to run the engine fast on this to pull the fuel through. not pretty, but will often start an engine which won't bleed 100% on starter motor alone.