110 johnson bogging

jmtodd523

Recruit
Joined
Jul 29, 2016
Messages
5
i need help. I have a 1988 Johnson 110 vro. I was on the lake today for a final test run. starts great and runs out great but after about 15 min of cruising I stop and check out the cave located on the lake. I start motor back up and take off and its bogging, but, when I trim the motor about halfway up it'll catch up and take off. it never does this when I first start the motor and take off, only after its up to operating temp... any ideas on what to replace or do ive replaces coils plugs and power pack plus gone thru carbs.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Some of the fuel in the carbs may be draining back into the tank. That would not sustain high rpm throttle till the fuel pump re-fills the carb bowls.
 

interalian

Commander
Joined
Jul 23, 2009
Messages
2,105
Try squeezing the primer next time you start it when warm and see if it still does it.
 

Fed

Commander
Joined
Apr 1, 2010
Messages
2,457
Had a mate with the same problem as you described and it finished up being a leaking primer valve.
I suppose you could test it by removing & blocking the input hose to the primer valve after you have first started & warmed it up for the day.
 

James R

Commander
Joined
Feb 1, 2007
Messages
2,660
When you trim the motor up you reduce the load and the motor does not need so much fuel to run up. The primer bulb will tell you its a fuel shortage. If its not the bulb or the hoses it is probably the fuel pump. If you have replaced a fuel fitting recently and used a cheap one the pump could be sucking air.
 
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Fed

Commander
Joined
Apr 1, 2010
Messages
2,457
jmtodd don't get confused between the primer bulb & the primer valve, they are 2 different things so if you are not sure just ask.
Theory behind the primer valve leaking was the warm motor getting a gut full of fuel after switchoff & again during cranking & warm/hot start up.

Flooding, tilting up helps it drain from the front of the carbs & reduces back pressure on the motor allowing it to clear easier.

Of course this 'flooding' didn't worry it on a cold start & run at the beginning of the day, it all fits.

If hand pumping the primer bulb makes it worse it would also point to a leaky primer valve.
 
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