motor won't run in water

[tacg]

i've got a johnson 50hp (not sure of the year the serial #is E3468528) that runs like a top out of the water but in the water it won't crank. I can lift it out of the water and it will crank right up .While it is running i can drop i in the water and it will run untill i idle it down then it will die and not crank back up untill it is out of the water.

 

[scipper77]

Re: motor won't run in water

are you running it out of the water with no water supplied to the water pump??

 

[tacg]

Re: motor won't run in water

when i had it at home i had the muffs on it and it did good then we put it in the lake and it wouldn't crank i tilted the motor up long enough to see if it would crank and it did i lowered it back in the water and it ran as long as i was giving it about full throttle when i backed off it died

 

[iwombat]

Re: motor won't run in water

It's more than likely not firing on one cylinder. While runnin on the muffs (and wearing gloves) remove a spark plug wire from a plug. You should notice a difference in RPMs. If you do, put it back and move on to the next plug. Once you find it you'll need to determine if it's a fuel or spark problem. Let's find the culprit first though.

 

[tashasdaddy]

Re: motor won't run in water

you also could have the idle set too low. when running on muffs, there is not any back pressure on the exhaust, when you put it into the water there is immediate back pressure, and the motor has to turn faster, to force the exhaust out of the exhaust housing. you should idle around 8-900 rpms on muffs, and then when in the water it will idle around 650-750, this needs to be fine tuned with the motor running, in the water, and in gear, it will idle a little faster in neutral, but the motor has to be able to idle in gear without dying.

 

[CharlieB]

Re: motor won't run in water

Lean idle mixture caused by dirty carb will not idle in the water.

How long since the carbs have been throughly cleaned along with a complete link and synch?

Usually this will cure most idle and off-idle problems.

 

[tacg]

Re: motor won't run in water

will this keep it from cranking in the water? I don't know how long it has been i just got the boat. and don't have a manuel for it yet

 

[tashasdaddy]

Re: motor won't run in water

yes. have you check the compression and spark on both cylinders?

 

[Tim Frank]

Re: motor won't run in water

will this keep it from cranking in the water? I don't know how long it has been i just got the boat. and don't have a manuel for it yet

Are you saying that the starter will not turn over the motor if it is in the water?
~ or that it will not RUN in the water?

 

[tacg]

Re: motor won't run in water

it will turn over no problem in the water but won't crank and run it's firing and getting gas. I can tilt the motor up and let the water drain out and it will fire up as soon as i hit the switch. Lower it back down in the water and it will run about wide open untill i let off the throttle then it dies

 

[tashasdaddy]

Re: motor won't run in water

i gave you the answer. you also have probably damaged your impeller, running it with out water.

 

[Tim Frank]

Re: motor won't run in water

it will turn over no problem in the water but won't crank and run it's firing and getting gas. I can tilt the motor up and let the water drain out and it will fire up as soon as i hit the switch. Lower it back down in the water and it will run about wide open untill i let off the throttle then it dies

OK, got it, thanks.
Difference in word use up here in canada I guess...
To me, cranking is the starter turning the engine over....and you hope, just before it catches and runs.

 

[jonesg]

Re: motor won't run in water

It will help to acquire a few items before using the engine,
trying to force it to run as-is will damage something.
Tash is right, you very likely fried the water pump impellor already.

Factory service manual (www.kencooks.com) NOT seloc manual.
Compression guage from autozone $27
Spark plug gap tester $9

Do a lot of reading here , its real easy to fry the ignition if you make a simple mistake such as hooking up the battery wrong (or loose).

I would go through that engine from top to bottom before using it,

Compression test it, spark test and rebuild carbs with rebuild kits, change gear oil with new gaskets on the drain screws.
its all simple to do.