Logo
FULL SITE MENU

1999 Johnson 40hp running erratic above idle

J

jeff_32

Member
I have a 1999 Johnson 40hp running erratic above idle. It idles great but once you give it throttle it runs like it is hitting a rev limiter. The previous owner installed a new power pack and made it have way across a small lake running good, then went right back to running bad again.

Any suggestions...rectifier, stator, timer base or all of the above?
 
It is best to do some simple testing.-----Test run with another tank and hose.----Post actual compression values.----Does spark jump a gap of at least 3/8" on both leads?---Check flywheel key.---Running with VRO in service and tested.----Or running with 50:1 mix?----Model # of the motor ?
 
When you say it "runs like it is hitting a rev limiter" you mean it's revving up & bouncing off the limiter?
Well if it's not making the boat lurch then I'm thinking it's your prop isolator.
 
Been put of commission for a bit. I'll get back on it and post numbers. It's a VRO pump and doesn't take much throttle. I did check compression and both cylinders were even, but I don't remember off the top of my head.

A friend of mine has a 2000 Johnson 40hp and has a similar issue. Idles great throttles up and then falls on it's face and jumps back to full throttle. I haven't been in his boat, he jokingly said our Johnson's must have gotten std's.
 
Back
Top