engine not starting

[farquart]

After finding suspicious looking white gunge in the prefilter of our Yanmar 3gm we changed the filter, refilled the tank with soltron treated fuel and primed the engine. We then tried several times to start it with no success. The boat has been out of the water since October and therefore we cannot eliminate the fact that it could just be cold but i am wondering if there is another reason for it not starting. We used the starting handle to prime the engine although have never been able to starting it in this way. Is it possible that the fuel bug is inside the engine and causing this problem. If so, any suggestions of what we do about it.

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[maxi]

Sounds as though you have not fully bled the injection system and that there is still air somewhere - it is unlikely that any 'bug' debris will have got beyond the primary filter.

It is important that, whilst trying to start the engine, you ensure that the seawater cooling is shut off. Otherwise repeated cranking can easily backfill the cylinders with seawater - do hope that this is not your problem.


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[dickh]

Definately it sounds as though you have not bled sufficiently. When bleeding, make sure you get fuel bleeding from the engine mounted filter first, then move onto the fuel pump and finally each injector. It will depend on your engine, I'm not familiar with the Yanmar. You will probably have bleed nipples/points on the filter and injector pump housing, then just crack open each injector in turn, closing when you see fuel without any bubbles. Then it should start easily.

<hr width=100% size=1>dickh
I'd rather be sailing... /forums/images/icons/smile.gif

 

[farquart]

The boat is not in the water at present so there is no sea water getting in, there is just antifreeze sat in the engine so it is probably the insufficient bleeding option. (hopefully). Will go back and try again. Thanks

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[AndrewB]

Diesel bug ...

.... is black and jelly-like, not white. If fuel is getting through then you should see it coming out the exhaust, if you crank for long enough. As well as blocked fuel, the other things that prevent starting are blocked air supply or inadequate compression during cranking - the last often due to flat batteries.

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[Johnjo]

Hi, not familiar with your engine, but it is usually possible to hear the injectors ping if they are getting fuel as you turn the engine over by hand with the decompressors lifted.
open the throttle fully and give it a good spin, should hear them, sounds a bit like a squeaky ping !

won't help you start, but will tell you if its getting fuel !...

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[chriscallender]

Agree that it is most probably air but another thought is does the engine have any preheat for starting cold & is it working? I have a Bukh, that has no preheating and usually takes a bit more cranking than it would in the summer, try pointing a fan heater at the air intake for a while and warming the air in the engine compartment and see if that helps.

Chrus

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[snowleopard]

the yanmar has no pre-heat. i generally find it needs about 3/4 throttle to start from cold.

when bleeding it is necessary to bleed the filter then the injector pump. it usually isn't necessary to bleed the injector pipes.

a few other checks you can make: check there is compression on all 3 cyls by turning the handle (possible stuck valve).

another way to check fuel is coming out of the injector by removing it from the block and seeing if it sprays when you crank over (an awkward job as you can't bend the fuel pipe). do not let the spray get on yourself as it has enough pressure to penetrate the skin. before refitting the injector, anneal the copper washer by heating it on a gas ring and dropping into cold water.

if you have compression and fuel, the engine will start.

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[scarlett]

If you haven't got electric power, a quick fix for low compression is a hand held blow lamp near the air intake. But take care.

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[Sam_Salter]

I've got a 2GM.
Assuming the system has been bled properly...
The Yanmar service manual has a write up on cold starting:
Put the throttle lever right over to full.
Press the start button, when it fires, release the start button immediatly & reduce throttle to half speed.
(Full throttle retards the injection timing for easier cold starting)
Sam Salter
C&C 26 Skye II
Ghost Lake Alberta

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[TheBoatman]

I have several 3 gm30 engines in our club boats and they can be a bit of a pig to bleed first time however once bled they start very easily.
You need to make sure that the manual lift pump lever is working correctly as it has a tendancy to stop on the top of the cam making it a bit ineffectual. I find the best way to bleed the system is to make sure the batteries are well up then loosen all the bleed screws and crank the engine on the starter motor, doing up the bleed screws in order from the filter towards the injectors. What ever you do don't stop winding the engine as soon as it starts to fire, wait until the engine accelerates away from you. All this is done with the throttle wide open? And it may well be 30 secs before the engine fires.
Best of luck
Peter

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[JSB]

One of the books I have on diesel troubleshooting suggests WD40 in the air intake whilst cranking (though not at the same time as the blow lamp!) the engine does not become dependent on this apparently.
John




























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