Marina 6HP Fourstroke Cutting Out

[LONG_KEELER]

Is the plug wet or very dry after a number of unsuccessful pulls ?

Sticky carb petrol float ?

 

[RivalRedwing]

A new plug every 4 years is not going to break the bank as a service item...

 

[VicS]

Good question. Back in 2017 the plug looked pretty normal. This time I haven't yet checked. And yes the oil has just been changed, although I don't think it was over filled. Both will be checked this weekend.

Do you know if the engine oil level is supposed to be checked with the dipstick fully screwed in, or just resting on the threads like Honda motorcycles? The manual does not say. If it turns out to have been over filled, I can suck a bit out of the sump to resolve the underlying issue, and I assume that running the engine for a few minutes will clear out anything left in the combustion chamber. Or is there some other step I should take?

Snipped from the manual

 

[gandy]

Thanks, that must be a different manual as mine says ...

Remove the oil fill cap and refill with 450 ml (15 fl. oz.) of oil. Reinstall the oil fill cap.
Idle engine for five minutes and check for leaks. Stop engine and check oil level on dipstick. Add oil if necessary.

I guess the second to last sentence could be taken to imply that the check is done with the dipstick fully screwed in. But it's interesting that there are different manuals. Mine is dated May 2000, and the quote is from the Maintenance chapter.

Anyway, unfortunately in a way I found the oil level to be perfectly correct right at the upper mark. I suppose there's a vague possibility it was over filled and the full power run made it swallow the excess so to speak. But I don't think it likely as I'd expect there to be a bit of tolerance before overfilling has that effect. With a new spark plug fitted it ran without faltering at all during some gentle testing while I took a run out to the mooring and back. Not yet a full test because I wasn't able to run at full power due to a number of paddle boarders nearby. I'll try to test at full power next time, as well as not overturning paddle boarders I'd prefer to do this where it would be an easy row back if the motor conks out.

 

[VicS]

Thanks, that must be a different manual as mine says ...
I guess the second to last sentence could be taken to imply that the check is done with the dipstick fully screwed in. But it's interesting that there are different manuals. Mine is dated May 2000, and the quote is from the Maintenance chapter.

I have looked at several manuals from 2004 to 2018 and they all say the same
but
I am reading the instructions for checking the oil level in the section on fuel and oil.

 

[coveman]

So, no wiser I don't think. Heading out to the boat I was 100% sure I was going to find the tank vent screwed shut. It seemed that would explain exactly what I found, running for a few minutes before cutting out, then restarting OK but only running 15 or 20 seconds before cutting out again. However the vent was fully open. The only test I could think of doing onshore was to connect up the fuel tank, pop the fuel line off the carburettor and try the priming bulb - that gave a plentiful squirt of fuel suggesting fuel line and filter and pump are all clear of blockage. I know the pump works because it ran at home without priming, so the pump had to do all the sucking up. So other than an internal problem with the carb, I can't see where an issue could lie in the fuel system.

On the water today, no problems at all. It's only a short run to and from the boat but bear in mind that last weekend I had to restart at least 5 times on the way over.

So the only thing I've positively done is fit a new spark plug. Could that have been the cause? I'm tempted to stick the old one back in and see.

Even though the vent is unscrewed it may be worth trying with the cap off to rule out a venting problem- I once had a vent that was still blocked when unscrewed.

 

[gandy]

I have looked at several manuals from 2004 to 2018 and they all say the same
but
I am reading the instructions for checking the oil level in the section on fuel and oil.

That particular mystery solved at least, I downloaded an operator manual and it has the wording you quoted. What I have is the service manual.

 

[VicS]

Mystery solved, I downloaded an operator manual and it has the wording you quoted. What I have is the service manual.