1GM10 Starting Woe...

I always crank my 1GMIO with the decompressor activated to ensure a rich fuel mixture when cold. This is "kinder" on the battery, anyway. Dropping the lever after about four to six revolutions results in a start. When it doesn't, I give the throttle a tweak open and repeat. It's smokey for a few moments, but once the governor has full control over the fuelling, it runs well. The engine had it's first top end overhaul last year after 10 years in service.
 
I've had several different issues with my 1 GM, but now before starting it I pump the fuel pump lever about 10 - 15 times before pressing the starter. Works every time, even if I forget to put the throttle half-way forward. I used to use the de-compressor lever whilst starting, but don't have to do so now.
 
Topcat47 said:
I always crank my 1GMIO with the decompressor activated to ensure a rich fuel mixture when cold. This is "kinder" on the battery, anyway. Dropping the lever after about four to six revolutions results in a start. When it doesn't, I give the throttle a tweak open and repeat. It's smokey for a few moments, but once the governor has full control over the fuelling, it runs well. The engine had it's first top end overhaul last year after 10 years in service.
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I used to do that with mine in the Impala.
However, a decent battery, fully charged made a huge difference.
A small solar panel to keep the battery fully floated might be worth it.
The OP's though, sounds like rings or other wear.

Even so, the faster you can crank it, the more it will tolerate wear and still start.
 
vyv_cox said:
Does sound rather like a compression problem. To get some more information, try squirting an oil can into the air inlet, not the air cleaner, while the engine cranks over. This will coat the bore and piston rings, improving the sealing of them. If it starts immediately it suggests the rings are poor. If it doesn't then it's something else. Check tappet clearances in case one is closed, holding a valve open.
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rotrax said:
I dont wish to piss on your fireworks, but if one valve was stuck closed it would be due to another fault.

The valve gear would be broken-anywhere from the cam operating the offending valve up to the rocker arm.

I favour-as others have suggested- set the engine JUST past compression, full throttle and hit the starter.

I could hand start the 1GM10 in the Hunter 27 OOD I had a share in.

Giving a diesel full throttle puts a little more fuel in the cylinder-or cylinders-and has the effect of increasing the compression a tad.

Worth a punt....................
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ghostlymoron said:
I don't think you have pissed on my chips. You've said the same as me only phrased differently.
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I'm certain Vyv can explain himself perfectly well but his theory related to a closed valve clearance, not a closed valve.
 
langstonelayabout said:
Having some probs with my 1GM10 engine starting.

It starts about the sixth (extended) crank. Before the engine finally catches and starts I'm pumping loads of blue smoke out of the exhaust but once it runs, it runs properly and starts properly all weekend.

Anyone any thoughts? I'm taking it out for a look-see this winter and would appreciate your thoughts of the potential cause. When it runs it runs well, if a little warm. The fuel (road-legal white diesel) is about a year old.

Many thanks in advance
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I'd think about the non return valves in the lift pump allowing the fuel to seep back
also agree with others re air leak. I cant see it being low compression as you say it runs fine once started for the whole week end, meaning it has time to go back to its usual starting temperature
I have a yanmar 2qm15 with the same symptons and have checked / anealed all the copper washers used the right size c spanner to tighten the fuel filter
compression is good no white or blue smoke and good overal running hence my thinking re the lift pump none return valves
I didn't want to take the lift pump off untill the boat was back at its winter moorings, now it is I shall take the lift pump off and check to see if I have an ac delco or other make ( I have a few makes in stock plus theres over 200 of em) pump that matches or even if the none return valves are the same size. I recon they coppied the standard ac delco type pump but cant be sure untill its sat here to check
 
mtb said:
I'd think about the non return valves in the lift pump allowing the fuel to seep back
also agree with others re air leak. I cant see it being low compression as you say it runs fine once started for the whole week end, meaning it has time to go back to its usual starting temperature
I have a yanmar 2qm15 with the same symptons and have checked / anealed all the copper washers used the right size c spanner to tighten the fuel filter
compression is good no white or blue smoke and good overal running hence my thinking re the lift pump none return valves
I didn't want to take the lift pump off untill the boat was back at its winter moorings, now it is I shall take the lift pump off and check to see if I have an ac delco or other make ( I have a few makes in stock plus theres over 200 of em) pump that matches or even if the none return valves are the same size. I recon they coppied the standard ac delco type pump but cant be sure untill its sat here to check
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Yanmar injector pumps are supposed to self prime.
But you could take the lift pump out of the question by feeding it with either a squeeze bulb primer, or a supply from a can raised a couple of feet.

Good thing to look at though. Lift pump and air leaks are likely culprits IMHO.
 
I have two of these engines in my Catalac 8M. When long crank times occur, I first bleed fuels system and if that doesn't fix it, then adjust the 2 valves. Valve adjustment on the 1GM10 takes about 10 minutes. One question, how long has the fuel been in the boat?
 
I used a 12V hair dryer up the air intake on my 1gm. Eventually continuing start problems explained by French Marine mechie - seems they'd had message from Yanmar abt tolerance drift on injection pump for some of production. They fiddled with the shims and it helped - meant that diesel was now squirted in at correct point in cycle. Just summat else to consider/confuse you
 
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