I'm on my knees here

[imported_stump jumper]

Need some help from the crew. I have a '91 200 HP Mariner Offshore. The motor was underwater, but pickled and was running great last week. Now I have developed a problem where themotor will not start unless in fast start. It runs fine in fast idle, but cuts off as soon as I bring to Neutral. I pulled 1 carbuerator off and it looked fine. I am getting spark at all 6 plugs. I am running off an external fuel tank to eliminate the possibility of contaminated fuel in the inboard tank. Any ideas where to look next?

 

[Windykid]

Re: I'm on my knees here

How long was it underwater?

 

[imported_stump jumper]

Re: I'm on my knees here

matter of hours. the motor was pickled and has ran great since that time

 

[Chris1956]

Re: I'm on my knees here

Sometimes the electronics will fail a long time after being underwater. My distributor trigger failed two years after being under saltwater for a week. Put a timing light on some of the cylinders at the fast idle. As you slow down, make sure the spark doesn't shut off (possibly bad slow winding on stator?). If Spark is still good, it is likely carb idle circuit.

 

[rickdb1boat]

Re: I'm on my knees here

I'd pull the carbs and give them a thourough going through. Idle circuit is probably plugged up...

 

[jmburock]

Re: I'm on my knees here

Did you take the thermostat housing off? Maybe it is clogged with sand from the underwater diving. Mine was clogged with sand and it didn't even go under- just from running in shallow water. I suspect your ignition components will begin corroding rapidly as well unless you took them apart/ alcoholized them to remove water, etc.