Mercury 15 hp 2 Stroke cutting out - Page 2

jeffstevens763@g · 14 July 2022, 19:56

When it won’t start have you primed the bulb again I’m kinder looking at fuel starvation float needle sticking or dragging air in

neil.mccrirrick · 14 July 2022, 20:19

Yes primed it will start again but then dies

neil.mccrirrick · 14 July 2022, 21:41

I was convinced it was air at the start of this. That lead to the carb rebuild. I’ll pull it again check all gaskets and ultrasonic clean

Still frustrating that it will run from cold and behave albeit with help from the primer to get it revving until back to slow running

TmMorris · 15 July 2022, 06:57

As it's a single carb that feeds fuel into a single aperture then normally you'd expect a carb issue to effect both cylinders.

Same with an air leak before the Reed valves.

With compression being confirmed as balanced and with seemingly the issue being a loss of power to the lower cylinder when hot, I'd be looking more at things on the other side to the air and fuelling supply.

I'd be suspecting electrical gremlins. I might do one final comp test when it's hot just to rule out a weird heat related air leak but I wouldn't be expecting to find anything.

Fuel ok. Air ok. Compression ok. Spark ok when cold. Engine starts and runs well.

When hot it seems like the bottom cylinder loses power. So I'd start rolling out the electrical elements that supply separately to the cylinders. My first assumption at this point would be a cooked HT lead but you've checked those and the plugs and the coils.

In theory we're looking at something before the coils but which potentially still sends a split signal. In my mind the last component that could be doing that would be the CDI?

Someone mentioned CDI earlier and I see you've got one on the way. That seems like the correct next step as this does seem electrical, heat related and confined mainly to one cylinder and you've checked everything up to the CDI.

neil.mccrirrick · 11 August 2022, 10:18

Still not resolved snd we have family round for a while now. Not electrical I’m fairly sure cdi no change.

I have found a a small cut no wider than the edge of a 20p on the rubber gasket on the reed cage. Tried to fill that with gasket sealant yesterday so maybe that will fix it?

Anyone know where I can get a replacement gasket? Been googling and come up with nothing so far

TmMorris · 11 August 2022, 10:38

Make one? Does it need to be rubber or just normal gasket material?

neil.mccrirrick · 11 August 2022, 11:01

It sits in a channel and has to be rubber. Not an easy think to make at all

jeffstevens763@g · 11 August 2022, 21:24

Cambridge outboards or ssi marine Neil

neil.mccrirrick · 12 August 2022, 19:45

Thanks Jeff. I’ve about run out of ideas with this now. Everything I know says it should be working. I’ve threatened it with a hammer still not given in.

As much as I don’t want to it’s off to a merc dealer I think

jeffstevens763@g · 12 August 2022, 20:17

Could be dragging air in the gasket, reed block ok not sticking?

A1an · 12 August 2022, 20:30

When it’s idling in the tub Neil, try spray some brake/carb cleaner in around the carb and gaskets, if the engine changes note you know you have a leak somewhere.

I’ve just had a Honda 10hp in that was running me out of patience, turns out to be a worn butterfly shaft in the carb that’s throwing the fuelling out. Only find this out by spraying brake cleaner at it.

neil.mccrirrick · 13 August 2022, 15:56

Alan you may well be a genius. Just started it up and sprayed. Definite rev increase from the joint where the carb meets the reed cage and also from where the bar passes through the carb body to the butterfly valve

Never separated the butterfly valve out never known one go. I’ll take it off now and see if I can lose the circlip and have a whole new set or challenges lol

A1an · 13 August 2022, 15:59

Sounds like a leak after metering, that’ll give you all sorts of weird symptoms.

neil.mccrirrick · 13 August 2022, 17:29

Took the butterfly apart nothing obviously wrong and it was pretty clean. Back together now. Took thd reed valve off and tried some sealant in the gap in the rubber gasket. I’ll let it dry and rebuild tomorrow.

Found another on flea bay so if it doesn’t work I’ll buy that and start prayer [emoji106]

A1an · 13 August 2022, 18:34

Quote:

Originally Posted by neil.mccrirrick

Took the butterfly apart nothing obviously wrong and it was pretty clean. Back together now. Took thd reed valve off and tried some sealant in the gap in the rubber gasket. I’ll let it dry and rebuild tomorrow.

Found another on flea bay so if it doesn’t work I’ll buy that and start prayer [emoji106]

If it’s drawing air through the butterfly shaft it’s usually easier to just swap the whole carb for a another. I’ve seen people put blobs of grease on either end to stop the air being drawn in but that’s just a bodge.

neil.mccrirrick · 14 August 2022, 08:17

I can see it coming to that. Have been looking for a carb to swap out but nothing has come up. Loads of yam copies made in China FYI

A1an · 14 August 2022, 09:04

I’d be very wary of buying one of the chicken fried rice units for obvious reasons.

Tommy c · 16 August 2022, 21:41

Quote:

Originally Posted by A1an

I’d be very wary of buying one of the chicken fried rice units for obvious reasons.

I'll 2nd that. Bought one for a tohatsu 3.3 2t and ended up buying a genuine. Didn't seal properly and was just drawing loads of air in

neil.mccrirrick · 19 August 2022, 14:21

New to me reed valve has turned up. Hopefully get it fitted over the weekend and the pesky thing is fixed

A1an · 19 August 2022, 17:17

Quote:

Originally Posted by neil.mccrirrick

New to me reed valve has turned up. Hopefully get it fitted over the weekend and the pesky thing is fixed

What’s up with the reeds Neil?

You’ll have triggers broom shortly?