mariner 50 hp 4 stroke 4 cylinder bogging down

[jimthorley]

hi guys see if any of you have any ideas on my problem, its been a long running one. i have had carbs cleaned last 2 seasons last one was sonic. outboard runs great then suddenly bogs down as soon as you switch engine off and restart full power is back. may run hours or minutes before doing it again. outboard mechanics i use think something may still be in carbs deep rooted and have advised renewing carbs. Very expensive.. would i be daft in thinking changing a coil pack may help?? i have ordered a used set from the states should be here soon.. have changed all fuel lines filters tank have a new set of spark plugs coming, its the restarting and getting full power back that makes me think electrical any advise would be welcome its one of these problems that even stumps the outboard mechanics as a weird one, but still its very annoying when it does it other wise a great engine its a 2000 year model believe its a real name is a 45 bodenese it runs with the Yamaha carb set up . compression all good its either carbs or electrical any one else had these woes
regards
jim

[ColinR]

I had something similar ages ago on a Merc 115. It was fine at speed but if I slowed down, typically coming into a nasty cross tide in a marina, it would cut out.

The issue was that there would be no pressure in the fuel system so I had to pump the primer bulb like fury to keep it going.

Like you I stripped and cleaned the carbs, replaced the fuel lines and even the tank.

I thought it was air getting into the system but the local merc service guy could not sort it.

Much as I'd love to tell you what the problem was I never solved it so I flogged the boat to someone who put a newer outboard on it. My final conclusion was that the fuel pump was failing once it got hot.

[shibbs]

I would say it wouldn't be the carbs if it runs ok after a restart, I would look down the electrical route.
I know how you feel trying to hunt down a problem though.
Good luck.
If as Colin says it was always after it had got warm or always cold etc etc then it would make more sense but as it is random, I'd go electric!
I may be completely wrong though..

[Ianfs]

Hi Jim

Welcome to the forum.

When the engine bogs, is the primer bulb still hard?

Have you checked the air intakes are clear on the engine cover?

[_Ed_]

Doesn't sound like fuel to me. If possible show me a pic of the engine or serial number?

[jimthorley]

Thanks guys. I am lean8ng towards electrical once the new coil pack arrives it should either fix it or rule that out as the cause. Does tend to be when engine warm.fuel pressure ok primer pump still hard. This outboard has a preheat system but the mechanic disconnected this as engine was harder too start with it connected. Ive never had bother starting outboard first turn of the key she springs to life runs great except for the boggingdown. Sounds rough as if a cylinder has dropped. Going to borrow dry suit and get in the water at shore and get a amp meter reading when its doing its problem..
Serial is 0g999137 cheers again

[jimthorley]

Doesn't sound like fuel to me. If possible show me a pic of the engine or serial number?

Hi ed serial number is 0g999137.
I get the odd misfire when she is running but not often. The mechanics told me they set carb screws at just over 2 turns when the recommended is 1 and a quarter turns could this make much of a difference?. Also wondering if it could be a issue with fuel pump? Thanks again
Jim