yanmar diesel problem

sqwert · Mar 26, 2011

I have a 3 clylinder tractor that I Bought not running, well I rebuilt the engine. It starts good and runs but seems like it is getting too much fuel, it idles ok with a little blue black smoke if you give it trottle it speeds up but lots of black smoke. sounds like a gas engine with the choke on. I loosened each injector line and it makes the same differece no restriction in the intake. I took the injectors out and run the lines to then and cranked it, the all show nice spray pattern. Any ideas?

msb · Mar 26, 2011

Not familiar with that engine. If by any chance, does the engine have a throttle plate? You could also have a restricted or plugged air filter.Remove the hose to the intake and see if that makes any difference.

sqwert · Mar 26, 2011

It does not have a throttle plate and I removed all the tubing to the intake manifold

Pair-a-dice farm · Mar 26, 2011

I'm not at all familiar with that tractor but is there any adjustment on the fuel pump timing? My fords can be fine tuned some by loosening the mounting bolts and turning the pump.

jm. · Mar 26, 2011

You have the engine out of time. either on the cam pump drive gear or the shims under the injector pump. Did you have the front cover off the engine or did you remove the injector pump?

mowr · Mar 26, 2011

If anything got sucked into the intake, it could cause this. I found a rag one time; could be somewhere in the manifold or even in an intake port of the head.

A blockage in the exhaust? Similar symptoms! Plenty of fuel without enough air.

Dave in Tx · Mar 26, 2011

On the pump facing the back of the engine, there is an acorn nut with a lock nut behind it. Under that acorn mut is a screw, loosen the lock nut and turn the screw in a couple turns. See if this helps. Fuel can be turned up and down with this screw. If turned in too far you won't get enough throttle. Probably one turn will tell you if it changes.

Dave in Tx · Mar 26, 2011

That screw can be turned with your fingers.

Anonymous-0 · Mar 26, 2011

Pardon Me ,i beg to differ and this is not my tractor , and we are all learning from everyones experience ,headaches and heartaches ,.. seems to me if motor were not properly timed it would not start very well ??. i think dave may have the right solution ,, and then again there could be a rag stuck in the air filter .

sqwert · Mar 27, 2011

I took the acorn nut off turned the screw in 2 turns had idle only turned it back out so it would speed up but still no inprovment. This engine starts so easy just hit the key and it is running. Is there somthing under the cover on the injection pump that I could check?

buickanddeere · Mar 28, 2011

Cam or injection timing problems.Valve clearance?
Cam and followers, were they re-faced? Who knows what dirt or salt water may have been through this engine? Cam wear that you can't see with your eye will cause problems.
Small diesels are exceedingly sensitive to deck height and valve sinking.
If the valves and seats were ground without facing the head to "raise" the valves. The loss of compression will cause various problems.
Too thick of an aftermarket or the wrong head gasket will drop compression too.

sqwert · Mar 28, 2011

I want to thank you all for the ideas. I advanced the timing and it got worse, then I retarded the timing as much as the adjustment would allow and it runs good now. I think I will need to retard the injector gear 1 cog. thanks again.

yanmar diesel problem

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