3.5hp johnson starts out of water but not in

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glen rosa

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My Johnson 3.5hp 2-stroke was running fine until someone borrowed it. Now when I try to start it in the water it just floods (with fuel) and refuses to start. If I start it out of the water it starts immediately and runs as normal! I've cleaned the carb and replaced the spark plug and tried clean fuel at 50:1 mix. I am now at my wits end and were it not for SEPA, the outboard would be at the bottom of the river! Can anyone please advise me of what to do next. It would be much appreciated. Thanks.
 
tashasdaddy

tashasdaddy

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Re: 3.5hp johnson starts out of water but not in

what year? when you say out of the water, are you starting it in a barrel full of water, of completely dry?
 
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glen rosa

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Re: 3.5hp johnson starts out of water but not in

It is a Johnson 2.5kw (3.5hp)I think the year is 2000. The model no. is j3rtssr.00
I started it dry and it caught immediately. I only ran it for a few secs to save the impeller then tried again. It starts fine dry. Attached to the dinghy... nothing but fuel flooding. I've adjusted the angle into the water to no avail.
 
tashasdaddy

tashasdaddy

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Re: 3.5hp johnson starts out of water but not in

looking at the diagrams, the only thing i can think of is your are not setting the throttle high enough for it to start. it is starting dry, because the is not any back pressure on the exhaust. the idle has to be set higher in the water to over come the back pressure. either that or a dirty carb. or low compression. check your compression, remove the plugs, insert a screw in compression guage, pull the rope till the compression quits going up, count the # of pulls, post the results, and the pull count. back here.
 
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glen rosa

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Re: 3.5hp johnson starts out of water but not in

I don't have my pressure gauge with me at the moment. But I have made some progress by turning the outboard upside down for a minute then starting it the right way round out of the water then putting my fingers over the pee holes and running it for a few moments. It now starts in the water like before. I wonder if transporting it in the boot of a car might have caused some water to go where it shouldn't. I'm gonna give it a good run tonight and see how it goes. I might be back, otherwise thanks for your assistance.
 
tashasdaddy

tashasdaddy

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Re: 3.5hp johnson starts out of water but not in

as long as you stand the motor straight up and let it drain, there is not water in the motor. it is self draining. are you shutting the fuel tank valve. if it has a self contained tank. could someone have messed with the carb settings?
 
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glen rosa

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Re: 3.5hp johnson starts out of water but not in

Some oily sludge ran down the shaft from the pee holes. I've increased the idle speed as suggested and the motor is now working as before. A bit of a mystery as to the exact cause of the problem. Hope you're having as nice weather in Florida as we're having in Scotland. Ta.
 
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