Engine starting problem

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dave_gibsea

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My 1GM10 is now 19 years old and last season it was smoking badly and not producing full power, however it was very reliable and always started first time. I decided to take a look and took the engine out of the boat last winter. The engine was (I felt) in good condition however the cylinder head was almost corroded through at the exhaust port and the mixing elbow had some pin-hole corrosion. The bore was good but a little glazed.



I had the bore honed (at Marine power) and fitted a new rings, I replaced the cylinder head and mixing elbow then carefully put the whole thing back together. I also has the injector checked and re-calibrated and changed all the filters. The engine turns over easily (with the decompression lever up) and has lots of compression with the lever in the normal position, in fact there is so much compression it is nearly impossible to turn it over TDC on the starting handle!



After fitting it took a long time to bleed the fuel through but eventually it started and I was very pleased as it ran beautifully. Since then I have used the boat three times and found the engine very difficult to start from cold. It turns over and over for ages and even using the decompressor for a few turns to get if spinning fast does not seem to help. It fires once or twice but doesn't pick up, after a lot of turning she does start (eventually).



Once the engine fires she runs very nicely, light grey smoke, no problems and she runs up to full revs under load. After starting once during the day she will fire "on the button" every time. Leave the engine overnight and the starting problem returns. One thing I have noticed is that it seems better when the weather is slightly warmer, worse when it's cold and damp.



I always start with the water inlet off. I always leave the engine at TDC-compression when leaving the boat.



I am stumped!! If the engine wasn't running so well once it's started I could suspect things like fuel but it runs so sweetly, revs and never misses a beat. The first time we ran it we motored for over two hours with no problems. I have also re-fuelled with fresh diesel but it made no difference.
 
This does sound like a fuel problem. A leak can be too small to let fuel out or cause problems in normal running, but still cause problems when the engine's been standing 'cos it's let a bit of air in.

Unfortunately I don't know of any easy way to find those kinds of leaks. Dusting all the joints with talc may show an otherwise invisible weapage of fuel. If you can figure out a way of putting the fuel system under positive pressure, that could help by encouraging diesel leakage that the talc will highlight.

Good luck!
 
I think they are all like that to some extent sir. Mine is 10 years old and is similarly, though not as bad as yours sounds, a little slow to start on colder days. I don't think turning it with the decompressor open helps; my theory is that it needs to turn over a few times to warm up the piston& head a little through compression. Sometimes when mine is being troublesome I find a good strategy is to turn it over on the starter for 10 seconds or so, pause, then turn over again and it nearly always starts.
 
"I always start with the water inlet off."

How quickly do you open it up, (what happens if you get distracted and forget?).

I'm not suggesting that this is the cause of your problem..... just seems strange, unless I've been missing something.

Richard
 
I open the tap within 30 seconds. Marine Power recommended this if the motor was slow to start to prevent the intake of cooling water should it back-fire and try to start backwards. Similarly I close it just before turning off.
 
I must admit that poor startingh cold and good starting hot, especially as there are no glow plugs make me think cranking speed. You say it is now very difficult to hand crank against full compression, if it is difficult for you it is also difficult for the starter. Has the starter been serviced, how new is the battery. Can you operate the starter with the decompression lever lifted then release it when the engine is turning well, this was the way se did it with hand crank engines.
 
Agree with Ken, my Yanmar can be a b*&&er to start when very cold and since many report this as an issue it must be an engine trait. Air filter element clean?
 
Battery was new last year and starter was checked out, the cranking speed is as good as it always was. The engine was a good starter before and I'm surprised to have this problem after the re-build. I have tried to satrt with the decomressor lever up to get it turning fast but is does not seem to help a lot.
 
When I had a 2GM, it used have cold start problems. Whilst this could be mitigated by giving it rather more revs on the governor, it wasn't until it started dying at inconvenient moments that I stripped the whole fuel line.
More by luck than judgement, I found that air was leaking into the fuel line around the barrel of the shut-off valve.

It meant the mechanical pump had to re-prime the fuel line every time the engine was started after a long stand.

The problem was cured by re-grinding the tap barrel.
 
Very slight miss timing has gioven me the same symptoms in a car, the old ford pinto engine was very prone to this after camshaft repcements, and the only solution on the car I had was a bigger battery.
 
Have you serviced the lift pump, Had the same problem on a brand new engine years ago and found that the non return valves had minute dirt on the rubber valves. This allowed the fuel to slowly drain back to the tank over a few hours,but once running was ok, after cleaning it was perfect. Hope this helps.
 
Where do you set the throttle before starting? I give mine about 3/4 throttle and she fires up fine. I know I have a fuel leak and am going to do some serious delving when I return home.
 
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