1970 johnson 6hp seahorse help please?

M

minnus

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to start i have cleaned out the motor with seafoam, cleaned the carb, got a carb kit and installed it, replaced the plugs, installed new gas lines on the motor and tank, checked for spark on both plugs(which are both good), set my idle, and thoroughly cleaned the powerhead. That being said, i need help figuring out why my motor will get up to about 12mph plane the boat but it never holds that speed for longer than a mineut then it dies back down to about 5 mph. the other thing is when it goes faster the motor starts puttering then starts going faster then just gradually dies back down. i have been working on this motor for about 2 months and am getting pretty frustrated with it. if anyone has any ideas on how to fix this i would greatly appreciate it.
 
C

crxess

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Messages
559
Re: 1970 johnson 6hp seahorse help please?

Sounds like you have just enough gas in the carb to get it going then it starts starving out.

Have you tried pumping the bulb when it happens? If you can pump the bulb and it tries to pick back up, the fuel pump is probable going bad.

Sierra replacement is only about $40 from iboats

If the bulb is staying hard and no change, you may have a plug cutting out. Possible faulty coil.
 
M

minnus

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Messages
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Re: 1970 johnson 6hp seahorse help please?

thanks for the quick reply. the bulb is staying hard, to hard even, but when the motor pickes up and goes it loosens up a bit. how do i check if its the coil?
 
C

crxess

Chief Petty Officer
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Messages
559
Re: 1970 johnson 6hp seahorse help please?

Best way is to be able to pull a coil wire while under load with the problem occurring.
If no change in motor and no cracking of electricity that wire is not firing.
If no change but Spark is present that plug is not firing.

Isolating which cylinder is missing will eliminate 1/2 the ignition parts or more.

Also possible weak spark on 1 set of points - burnt/closed up - could cause spark blow out at higher rpm's
 
M

minnus

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Messages
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Re: 1970 johnson 6hp seahorse help please?

thanks for the help. ill try that tommorow and get back to you
 
M

minnus

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Messages
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Re: 1970 johnson 6hp seahorse help please?

i didnt get a chance to check the plugs underload. bad weather got to me early i'll get back to it this week though thanks for the help
 
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