Engine still not running / need advice

[mauidan15]

So I'm calling a mechanic and going to have to wait a couple of weeks till he can come see me. Wondering if anyone has any ideas to get me going in the right direction until he gets here.

A couple of weeks ago I was out and the engine started to rev down, ramped back up for a while and then down again and just shut off. A little bit of white smoke came out and that's about it. Since then I've removed and cleaned out the fuel tank. Polished the fuel and have bleed the fuel system out, changed the fuel filter a couple of times. I've pretty well determined it's not a fuel issue. When I go to start the boat it turns over strong but never catches a spark like it's actually going to start. Guessing its possibly a compression problem? The engine is a 3GM Yanmar. Any suggestions apprieciated.

[theartfuldodger]

I must think that you also bleed the injectors lines to see if the pump is pushing fuel. To determine if you have compression remove one injector, disable the fuel system and have some one turn the engine over. If it was me I would put my finger over the injector hole and see if there is compression. The other possible problem might be timing, hope this might help a little

[Sailormann]

So I'm calling a mechanic and going to have to wait a couple of weeks till he can come see me. Wondering if anyone has any ideas to get me going in the right direction until he gets here.

My advice is leave it alone because if you haven't been able to fix it by now, further tinkering will probably just make it worse


...ask me how I know this...

[theartfuldodger]

well I'm a marine mechanic and was just passing along some help, of which most sailors should be able to perform if not you might want to consider a small engine introductory coarse

[Faster]

If the engine has, up til now, started easily then a sudden loss of compression is kind of unlikely. If it's been difficult and slow to start, esp when cold, then it may be that you've been "on the edge" of adequate compression for some time, and it's finally gotten to the point of not running.

Your symptoms do sound like a fuel problem initially, and aside from a major compression problem, fuel delivery will continue to be the most likely candidate. Fortunately injection pump failures are quite rare too, so it may not be a costly fix in the end.

[homarus]

Here is my two cents worth. You may have a air problem. A cracked fuel line or a loose fitting. This will occur between your fuel pump and your injectors. If you had a compression problem, it would be getting worse over a long period of time. If this is a problem that has just happen then air could be the problem. Check all fittings past the fuel pump gaskets on fuel filters. Remember you should have two fuel filters primary and secondary. Good luck.

[homarus]

Sorry about that Iam losing my mind. The air problem will occur between your fuel tank and your fuel pump. Or the suction side. Still check all fittings and hoses.

[paulk]

Just a guess, but if the engine was running, then slowed, then stopped, the first thing I would guess would be a problem with the injectors. Crud plugging them up so that there wouldn't be a mist of fuel to ignite, just a dribble of heavy oil that won't do anything. If the engine was running, compression existed. The other component of cumbustion- oxygen- is not really an issue - I have heard (though it may be a "marina myth")of diesel engines running underwater, with combustion oxygen coming from the air bubbles that got mixed into the fuel itself as it sloshed around in the tank. You don't mention doing anything about the injectors, or where you are. In our situation, wintering over the engine might enable all sorts of crud to accumulate in the lines leading to the injectors, even after going through the filters. I've also heard (another marina myth?) that checking injectors with your fingers is a good way to get a nasty infection as oil from working injectors gets shot into your tissues. (just a caution) Sometimes visual observation is enough. Good luck!

[camaraderie]

I'm with artful...did you bleed the whole system? High pressure pump and each injector?

[rogermrm]

Remove an injector and reverse it so it will atomise into the engine bay, a quick press of the start button by a second person - sight (Also hold a sheet of paper over the nozzle to check the spray pattern) if there is a fine atomised spray - if not then check for blockages - clean all pipework and bleed the system, prove fuel flow up to the injector.
Do not put your hand on the atomising nozzle as the pressurized fuel can penetrate your skin and make you very sick.