Johnson lacks power after initial acceleration - 1989 - Pull Start - 2 Stroke - 40 HP

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richuk09

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Jun 13, 2012
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Hi all,

I have a Johnson 1989 2 stroke pull start outboard engine. Has a slight problem which I hope someone can help me with?

The engine starts 1st pull every time and runs very well on idle. The problem I'm having is when I accelerate on full throttle the engine gets to full speed and my boats planes. This lasts for 2 - 3 seconds and then decreases to half power if that.

Haven't got a clue what's going on. Seems a bit strange as I hits full power well then starts to slow down.

Any help would be much appreciated. It's very frustrating!!!!

Thanks in advance

Richard
 
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richuk09

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Re: Johnson lacks power after initial acceleration - 1989 - Pull Start - 2 Stroke - 4

Any help would be very much appreciated!!

THANKS
 
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Daviet

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Re: Johnson lacks power after initial acceleration - 1989 - Pull Start - 2 Stroke - 4

Does it help if you pump the primer bulb when it slows down?
Might have a restriction in the high speed jet not letting it get the proper fuel for high speed operation.
Have you ever serviced the carb?
 
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richuk09

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Jun 13, 2012
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Re: Johnson lacks power after initial acceleration - 1989 - Pull Start - 2 Stroke - 4

Daviet said:
Does it help if you pump the primer bulb when it slows down?
Might have a restriction in the high speed jet not letting it get the proper fuel for high speed operation.
Have you ever serviced the carb?
Click to expand...

Hi,

Thanks for your reply!! I havent tried the primer whilst driving. Does this help? The carb was serviced a long time ago!! Could be 5 years or so. Does it need a good clean?

Thanks

Rich
 
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Daviet

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Sep 24, 2008
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8,958
Re: Johnson lacks power after initial acceleration - 1989 - Pull Start - 2 Stroke - 4

By pumping the primer bulb you bypass the fuel pump, if that fixes the problem, you need to check the fuel pump for flow and pressure.
You could also have a restriction in the high speed jet that you would check and clean when you overhaul the carb.
 
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richuk09

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Joined
Jun 13, 2012
Messages
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Re: Johnson lacks power after initial acceleration - 1989 - Pull Start - 2 Stroke - 4

Daviet said:
By pumping the primer bulb you bypass the fuel pump, if that fixes the problem, you need to check the fuel pump for flow and pressure.
You could also have a restriction in the high speed jet that you would check and clean when you overhaul the carb.
Click to expand...

Hi,

thanks!!

After checking, my lower cyclinder doesnt seen to be sparking as good as the top one. Could this b a factor?

Cheers
 
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richuk09

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Jun 13, 2012
Messages
5
Re: Johnson lacks power after initial acceleration - 1989 - Pull Start - 2 Stroke - 4

Hi,

Any more information would be great.

Thanks

Rich
 
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