95 Johnson 40 in limp mode?

finneus

Recruit
Joined
Sep 15, 2017
Messages
5
95 Johnson 40 tiller electric start and choke. Ran fine all day. Then about 3 minutes after takeoff, lost about 80% power at wot. Drove back to the launch and still had only about 80% power, running smoothly, and every few minutes would have a quick surge of full power. Is this limp mode? Never experienced it before but that’s what it felt like. What would cause it!
 

fireman57

Captain
Joined
Aug 24, 2004
Messages
3,811
Yep. Make sure you use an open air spark tester. 15 bucks maybe at you local auto cheap stuff store. As Joe Reeves told me 20 years ago make sure that it jumps 7/16ths inch with a bright blue SNAP. If it is orange then swap coils and see if the problem follows.
 

jakedaawg

Rear Admiral
Joined
Jun 26, 2012
Messages
4,275
A warning horn should have sounded.

You need to do a compression test 1st.

Does the warning horn beep once when you turn the key one click to the right?
 

finneus

Recruit
Joined
Sep 15, 2017
Messages
5
No warning horn sounded (i think prev owner bypassed it). Yes it beeps once when turning key on.
 

glust

Petty Officer 2nd Class
Joined
Jan 23, 2012
Messages
141
Had a similar issue and found it was the fuel tank not venting and basically vapor locking. Did you notice the primer ball collapsing while running? Not sure if this is your issue or not. Just throwing that out. If that is not your issue throw it completely out I guess. Good luck!!
 
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