1986 johnson 140 bogging down at wot

[imported_skeeter1]

my 140 idels perfect and runs fine up to 1/2 throttle, pass that it barely runs, no power at all, I found today that if I push in the choke all cylinderfs kick in for that split second, soon as I let go of the choke she bogs back down. all 4 carbs have new kits in them, new fuel pump diaphram kit and new fuel line bulb. after all this was installed it ran great until today when it started all the above
what I am I overlooking or what do you guys think?
thanks

 

[emdsapmgr]

Re: 1986 johnson 140 bogging down at wot

The engine may be starving for fuel. Try squeezing the primer bulb when it starts to bog. See if it picks up rpm's. If it runs properly while squeezing the primer bulb, it could be the fuel pump or a fuel restriction, like the anti-siphon valve.

 

[jtexas]

Re: 1986 johnson 140 bogging down at wot

welcome to iboats.
Sounds like fuel starvation all right.
Inspect the line from the tank to the carbs, also the vacuum pulse line to the fuel pump. Filter(s). Tank vent.
Re-check your throttle plate synchronization.

 

[guywithboat]

Re: 1986 johnson 140 bogging down at wot

I had the same issue with my 72 Evinrude. I rebuilt my carbs. It is most likely because the needle located in the float bowl is not seating correctly. Replace the needle [colour=red]AND [/colour]the seat. Check your high speed jets/ports as well.

Good luck

 

[imported_skeeter1]

Re: 1986 johnson 140 bogging down at wot

all 4 carbs have been rebuilt with new kits/needles/seats etc
what/where is the anti siphon vavle (primer bulb?)
thanks guys

 

[jtexas]

Re: 1986 johnson 140 bogging down at wot

If you have a built-in tank you may have an antisiphon valve in the fuel line at the fitting on the tank. Not sure why an outboard needs one anyway.

She ran great until today and now she only runs above idle with the primer switch activated, there's limited possibilities. Hitting the primer switch should flood it out and kill it. Clogged carbs. If it was a bad fuel line or faulty pump there wouldn't be fuel in the carb bowls. Must have picked up some debris from somewhere. Throttle plate synchronization.
Could air be getting in around the carb mounting gaskets?
Is it spitting fuel back out the carbs?

 

[imported_skeeter1]

Re: 1986 johnson 140 bogging down at wot

will check for fuel spitting back out the throat, one was doing that before the rebuild, stuck needle
will go through all of the checks you guys have suggested, runs great on the muffs (as they all do!!)
will keep you advised
thanks