df9.9 runs for 5 seconds

[Michawilden]

Hi All,

DF9.9 electric 2015, carb version remote control
I got an outboard from a friend. It has sunk, they took it out of the water and gave it to me( after a week).
Got the water out and got it running properly. changed the oil a few times. It ran well for a couple of hours. I let it run multiple times for an hour to get all the water our but oil is still milky.

Now the last time it would not stay running. I start it, it runs well on two cilinders for 5 or 10 seconds and than the lowest cylinder cuts out. It shakes and it dies. When I start it up immediately, same thing happens. runs on two cylinders and lowest cylinder cuts out.

Lowest spark plug is moist ( fuel). It does spark however. When I pull the plug when it is running on the top cylinder, big arcs jump to the powerhead/ metal. But it does not change how the motor runs.

Did a compression test, both on 145 psi.

Since the oil stay milky, I suspect that the lower cilinder gets water inside and therefore quits. It takes the water like 5 seconds to reach the powerhead. But I ran it outside the bin with the lower unit in the air and the same thing happens.

I do not get an overheat/ low oil pressure light. I cleaned the carb a couple of times now. Changed out the ignition coil with another, no change. swapped the spark plugs and the problem stays in the lower cilinder. Now I ordered new sparkplugs to test those.


Else I am stumped. Anybode else might know what could be the cause of the lower cilinder dropping out?

 

[99yam40]

does it keep running if you throttle up some?
does pumping the primer bulb help to keep it running?
I know nothing about that motor, but some motors adjust timing and enrich fuel during start up.
timing is easy to check with a timing light, but I have no idea if or how that motor would add extra fuel at start up.
if the pilot(idel) jet on the lower cylinder is restricted, it would stop working once the enrichment stopped

 

[Michawilden]

Thanks for the reply. It is a 2 cilinder with 1 carburettor.
If I play with the trottle I can prevent it from dying but it takes a lot of effort.
I dont think this one adjusts the timing. There is however an electric choke. Not a butterfly valve but a small throtte body with a needle. I think, when cold, the body is above the jet so it feeds extra fuel. With the ignition on it lowers the needle + body into the jet which closes it after a minute?
But with only 1 carb that does not add up.
Pumping the primer bulb does not help. And the weird thing is that if it dies and I start it after a few seconds. It starts on 2 cylinders again

 

[99yam40]

well that is strange.
if only one carb, then I do not see how it could be a fuel problem unless an air leak happens or maybe a leaking fuel pump could be dumping too much fuel into just #2 somehow.
BUT since this is a 4 stroke, I do not think that would be possible.

I would hook up a timing light to monitor the spark on #2 to make sure it stays steady even when that cylinder goes out

 

[Michawilden]

I will check with a timing light. The motor has 2 sparkplugs igniting simultanously. Just one ignition coil for both cylinders.
I had a motor once that sparked correctly outside the cylinder but didn't spark inside. Hope thats the issue with this motor as well. Spark plugs will arive tomorrow.

 

[Michawilden]

It turned out to be a clogged idle jet.

 

[99yam40]

thanks for reporting back what the problem was.

But I still do not understand how that would have affected just one cylinder, with only one carb for both cylinders.

 

[Michawilden]

Maybe that the lower cylinder ran too lean and did not ignite? I don't know but I am happy I found the problem.