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lordpoltimore 02-21-2010 11:04 AM

yanmar 2qm 20 will not start
i just put a new fuel filter in the engine and new fuel , the engine ran for 5 minutes and stopped , the filter i replaced was the fuel water seperator and i had not swich on the fuel tap so i bleed the system to the injector and now the engine will not start, i have made sure 5 times that there is no air in the system but still it will not start , the only shut off is when you thottle the engine to a stop no fuel cut off everything is mechanical this is a basic engine any help would be great

sailingdog 02-21-2010 12:04 PM

Did the engine work properly before you changed the fuel filter?

If so, considering that the only things a diesel engine need to run are fuel, air and cooling water... and that you've mucked with the fuel filter... it is most likely that you've got air in the fuel lines...

klem 02-21-2010 01:06 PM

I agree with sailingdog that the most likely problem is fuel. Either you have air in the system or your new fuel is bad. Why did you put new fuel in in the first place?

Regarding bleeding the system, you have to get all of the air out, not just most of it.

sailingdog 02-21-2010 01:36 PM

It could be bad fuel, but I think that if you bought from a reputable vendor, that is less likely than the lines not being bled properly or an air leak in the lines. If you replaced the fuel filter/water separator, did you double check the o-ring on the filter??

wwilson 02-21-2010 01:56 PM

Loosen the No. 1 injector and crank the engine. If you see fuel being expelled, your fuel pump is working. If not, let it crank a few times to be sure the air gets forced out. If the engine tries to start, tighten the injector (while it is cranking - and spraying some diesel) and it probably will start. When you crank the engine for a while, it is often a good idea to close the raw water intake. This may seem counterintuitive, but the engine will certainly not overheat during cranking (or for quite a few minutes after it starts). The closed raw water intake will keep the engine from filling the exhaust elbow then flooding the engine with seawater. Do reach in and open the seawater inlet once it restarts - mind the "spinning" parts on the front of the engine.

rikhall 02-21-2010 02:29 PM


Originally Posted by wwilson (Post 572270)
Loosen the No. 1 injector and crank the engine. If you see fuel being expelled, your fuel pump is working.

I am not a mechanic and Wilson might be, but me, I would leave the "loosening of the injector" to the last thing I check.

I have the exact same engine and until I got the fuel line bled up to the filter on the engine, mine would not run either. In the ten plus years I have had Yanmars, I have never had to bleed further than the "on the engine" fuel filter.

Diesels are easy - all they need is fuel, air and cooling. I have never sailed outside of Canada and the USA and here, I have never encountered bad fuel.

Best of luck with this.


wwilson 02-21-2010 03:00 PM

Hi Rik,

No, i'm not a diesel mechanic either. I did have a very good diesel mechanic teach me how to bleed the engine though.

There is no reason to be anxious about loosening the injector (at the cylinder) no harm will be done in any case. I did not mean detach - only loosen a turn or two. The engine's cranking power and the fuel pump's effectiveness are just a whole lot more effective than the little "finger pumps" normally used. And, if the air is in the portion of the fuel line between the finger pump (near the secondary filter) and the injector, the pump has a very hard time expelling it.


lordpoltimore 02-21-2010 04:57 PM

thankyou all the engine ran fine up to the point were i starved it of fuel , i have bleed it at the lift pump and then at the injector i let it bleed or a minute with the engine on its decompression mode there was fuel pouring out as i open the injector is already under pressure , the diesel was from hess gas station the engine , the oring on the filter was replaced

Stu Jackson 02-23-2010 10:26 AM

A friend of mine had this problem. He never went so far as to pop an injector, and I wouldn't either. Turns out he had bought a dented new fuel filter. Grabbed is backup and put it on, bled the engine and all was fine. So in addition to checking the O ring, check the body, too.

lordpoltimore 02-27-2010 12:08 PM

found the problem , on this engine the injector pump is built inside the engine all you see is 2 pipes comimg out though a housing on this housing behind the pipes is a bleed screw there was still air there once i bleed there engine started.

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