Yanmar 1GM10 won't start

[Gatordoc85]

My 1GM10 diesel is proving very difficult to start this spring. I have tried to bleed the fuel lines and I get good clean fuel coming out of the filter and the manual fuel pump as well as the fitting at the high pressure pump. I can get fuel to come out of the line as it goes into the injector. However, I can not get any fuel to come out of the fitting that goes from the injector back to the fuel tank. The engine turns over well and it will catch and run for only about 15 seconds after releasing the starter button. Any ideas?

 

[jollyboy]

Are you sure you have fuel coming through to the injector? I had that problem after bleeding my 1GM10. It ran for about the same length of time and stopped. I solved it by bleeding the hex bolt just before the injector. Has run perfectly since.

 

[25931]

My 1GM10 diesel is proving very difficult to start this spring. I have tried to bleed the fuel lines and I get good clean fuel coming out of the filter and the manual fuel pump as well as the fitting at the high pressure pump. I can get fuel to come out of the line as it goes into the injector. However, I can not get any fuel to come out of the fitting that goes from the injector back to the fuel tank. The engine turns over well and it will catch and run for only about 15 seconds after releasing the starter button. Any ideas?

That was one of the several problems with our Yanmar that we cured instantly. We replaced it with a Beta.

 

[ghostlymoron]

A marine diesel such as a gm10 only requires fuel and compression to run plus air of course. If you've got fuel to the injector, maybe the injector needs checking? Also check the air filter.

 

[srp]

You may well not see anything in the fuel return line - neither of the 1gm10's I fitted from new seemed to produce anything when I checked.
It might be worth checking the exhaust - eg a blocked elbow, collapsed rubber exhaust hose or a blocked waterlock could prevent the engine from starting. Or even a blocked air inlet (very unlikely unless someone laid it up last autumn with an oily rag stuffed up the inlet).

 

[Topcat47]

A marine diesel such as a gm10 only requires fuel and compression to run plus air of course. If you've got fuel to the injector, maybe the injector needs checking? Also check the air filter.

* the "stop" lever on the engine hasn't jammed, has it? Don't rely on the push/pull knob, check that the lever that operates the rack on the HP fuel pump moves.

1. I always run mine up on the starter motor with the decompressor lever up, then close it off. This gives an injection of excess fuel and helps the cold engine both to start and continue running as there is no cold start on the 1GM10.

2. If the engine isn't hard to turn over on the handle, it probably has low compression. This may be due to anything from a stuck vale to a scored cylinder so eliminate the easy stuff first. Test the decompressor to see if turning over is any easier with it "up". then remove the rocker box cover (carefully if you want to keep the old gasket, Yanmar ones are dear and the old one's can be re-used with a smear of hylomar) and check if the valves both move as you turn the engine over. If they do check the valve clearances with a feeler gauge, if they're closed up this may be the problem. If all this is apparently OK but you still have low compression it's a head off job. You might be lucky and have a blown head gasket. While the head is off, check the bores for scores, then lap the valves in the seats if they're not burnt, take the injector for a service anyway.

3. If you have compression, there may be a blockage in either the inlet tract or the exhaust system. These are fairly easy to check. If they are clear then it's a fuel problem. It could be the pump, the governor or the injector. If you don't feel confident enough to tackle this get your friendly neighbourhood marine engineer to remove the pump and injector for a service, replace them and re-commission the engine.

Hope this helps.

Don't forget the 1GM10 is susceptible to problems arising from water entering the exhaust port from the mixer elbow. This is a worst case scenario, however, I know of two engines resuscitated by a good cast iron welder and machinist so all is not necessarily lost even if this is the problem.

 

[pete]

May not help but I had a 1GM10 for 12 years, it had very good compression but over that time I had a couple of problems on the first start of the season caused by what I presume was slight rust on the valve seats after a bit of cranking with the decompressor on (in short spells to prevent cooking the starter motor) and a drop of oil in the air inlet dripped over the inlet valve it started and was OK for the rest of the season. Same happened to a friend boat with the same engine. make sure that you turn off your seacock when cranking until it starts if you are afloat to prevent flooding it.

One season the engine became very bad to start but when it did start it ran perfectly until next cold start time, eventually we tracked it down to a link lever that connected the injection pump to the governor internally, it is spring loaded and after we removed the pump we noticed that the link lever had not springing back, once it was released it never caused a problem again. I guess it put in more fuel for starting. This lever can be reached through the oil filler hole with your finger (when the engine is stopped)