Yanmar L90 problem

[kapis]

Hi all, maybe somebody can help me - the prblem with my yanmar engine is that if I crank the engine with starter - I get smoke coming out of the exaust and thas it, the engine will not run, yesterday I stripped down the engine to see if there is some problem with piston/rings/valves but there everything seems to be ok, also when I took the head off - there were plenty of fuel in pistons swirl chamber so maybe there is some problem with injector itself (not atomising the fuel) or maybe the problem is with injection timing. So I was wondering if someone can help me with guidelines of testing/setting things right?

Thanks in advance,
kapis

[smokyjoe]

You should be able to find the manual online for the Yanmar (check the "engine manuals" links in this group). Sounds like me that either it is too cold for the fuel to really ignite well (the smoke you are getting is mostly fuel vapor), or as you say the timing or vaporisation of the fuel is off. The check valve in the injector may be coked up and stuck (or the spring broken) which will cause the injector to just squirt and not have a good patterned mist- this will also cause the injection to occur way too early and by the time compression reaches it's peak at the top of the stroke the fuel is mostly just sitting in a puddle in the middle of the piston. The manual will give you the method of setting the fuel pump timing. You may be able to connect the injector to the fuel delivery pipe outside the engine and look at the spray pattern, but I'd do that outside, and wear good safety glasses! As you probably know the fuel is sprayed under such pressure that it can blow through your skin before you know it, and the highly atomised fuel in the air will ignite if there's a spark, etc. This is a thing I've done but cringe when I've had to do it. The injector should, when turning the engine over by hand, spray the fuel in a fine cone-shaped mist with no dripping- after the injector sprays, there should be no drips either. It should be a very quick "pffft" and stop. If you do get the engine started and the injector isn't spraying properly (lop-sided pattern, dripping, etc.) you may burn a hole in the piston or worse! Also, I'd check the compression pressure if you can borrow a compression gauge that'll fit the Yanmar. Usually the gauges come in a set with many adapters to fit a variety of engines. I bought a cheap Chinese one on eBay to use on my VW that just happened to have an adapter for a glow plug hole that fits the threads in the ignition paper hole on the old Hatz engine I'm using on my bike.

Good luck

[kapis]

Many thanks for the reply, I'l try to check the spray pattern as soon as I put the engine back together I will post then results

[Sphere]

Just be careful. No touching the tip with your fingers, and point it away.

[kapis]

hello all

just wanted to update you - today checked the the nozzle and it is not producing mist - it just squirts fuel, so I took it aparts and looks like somebody already has messed with the nozzle - there was some hand made washers to regulate pressure etc, etc.

so the question is - will this nozzle fit my engine : http://tinyurl.com/2wtzbja - looks like it is for chinese clones

or maybe I have to change the nozzle tip only?

[andrewaust]

That nozzle on ebay looks like the one you need, if in doubt ask the seller if you can return it if it's not. If someone has been stuffing around with the injector you already have I'd change it. Diesel specialists would charge more then a new injector to just inspect the old injector "unless you know someone" let alone do the repairs to bring it back to a serviceable state.

PS: If someone has been mucking around with the injector go over the rest of the engine including the pump just in case other places have been messed with.




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