Johnson 70hp not throttling up

[j_c_95]

Hi all. I have a 84 70 hp Johnson.
When under load and cold it will start up fine
And get out of the hole with no issues.
After it gets warmed up it will not throttle up
Unless I trim the motor up. Then it will take off and run at full throttle.
I am assuming by reading the threads it could be stator, power pack?
Any help would be greatly appreciated.

 

[boobie]

Re: Johnson 70hp not throttling up

When it acts up do a cylinder drop test on it and see if it's hitting on all 3 cylinders.

 

[j_c_95]

Re: Johnson 70hp not throttling up

Boobie
Thanks for the response. I did a cylinder drop test and didn't see any drop in either cylinders. Something else I can check or look for?

 

[boobie]

Re: Johnson 70hp not throttling up

How did you do the test and at what rpm ?? And what cylinders don't respond ??

 

[j_c_95]

Re: Johnson 70hp not throttling up

I put it in a tank of water and started it up pulling 1 plug wire ata time and I had a drop in rpms in each cylinder.

 

[boobie]

Re: Johnson 70hp not throttling up

Did you do this when it was acting up ??

 

[glenn property of pam]

Re: Johnson 70hp not throttling up

could be a lot of things like a coil failing when hot or a carb needle flooding one cylinder (running rich leading to a fouled plug). A tiny tach is a cheap way to test the coils as you can keep the cowling on during the test so everything under the cowling stays hot. If the tach reads correct when the problem happens then stop the motor and move the tach to a different cylinder (the tach winds around the plug lead so it quick to remove and replace on a different wire). how far are you tilting the motor, a little or until the exhaust is no longer under the water?

 

[xjdriver]

Re: Johnson 70hp not throttling up

Mabey somehow the fuel line is pinched a little with the motor all the way down then when you trim up its fine, lol a thought

 

[j_c_95]

Re: Johnson 70hp not throttling up

Boobie yes I done this as it was acting up as it
Does this always when it's gets hot.
I trim the motor about 3/4 out to get it moving. A
Side not if this will help is when idling after getting hit it will idle high for a few seconds than dropping down back to what I would call normal.

 

[pn]

Re: Johnson 70hp not throttling up

+1 on checking your fuel system. tank to carbs.