1973 johnson 25 hp one cylinder not firing

[boydog40]

everything installed, it cranked right up in the tank ran fine, put it in the water, hammered down, she took off then died, cranked back up no problem but is only running on one cylinder again. why does it keep dropping a cylinder? new coils, new points, new condensors etc
aggravating

 

[jimmbo]

What parts haven't you changed? Wires? Plugs? What about connections and grounds?

 

[oldboat1]

well, kind of a turnabout question -- but are you sure it's only running on one cylinder? Not a fuel issue, for example?

With all the new parts, I would keep it simple -- expect to find a simple problem (think points). I don't recall if you did a compression check. You should get some number for at least a baseline. Look for maybe 125 and even.

 

[boydog40]

I will crank it tomorrow in the tank and pull a plug wire to eliminate a cylinder, sure acts like it runs on one cylinder, tries to kick in, (I can hear it/feel it) I will try to keep it simple! and revert back!

 

[Newyota]

Just wondering if it is making like an intermittent loud knock type noise that sounds like the engine is going to throw a piston and the engine gives a sudden jerk!Not a constant rod knock or bearing going bad noise.If that is what it is doing it may be a lean sneeze.I had this on my 20hp and had no idea what it was till I watched some videos of others doing the same thing.

 

[boydog40]

it will give me the OMC sneeze, with no power, I can feel it try to kick in, but mainly running on one cylinder. I will recheck the carb setting as well. thanks

 

[boydog40]

update, reset the points to 22 (had them set at 20) fire right up ran for a couple of secs then died cranks back up runs couple secs and dies, not long enough for me to adjust the carb correctly and I have blisters on my fingers from pulling it time after time!
both cylinders firing now! woohoo but cant keep it running

 

[oldboat1]

Don't touch anything! But see if you can keep it running by squeezing the primer pump to keep fuel flowing.

 

[AlTn]

are you advancing the throttle to the throttle stop with the motor in neutral as part of your starting procedure?

 

[boydog40]

oldboat 1 - new fuel pump so bulb stays tight,
al tn, yes throttle is in "start" position

 

[AlTn]

if you are speaking of the throttle position "band" on the tiller handle...use that more as a directional guide for increasing and decreasing the throttle position...I'm describing actually twisting the throttle handle ccw till it hits the neutral stop when the motor is in neutral..this will partially open the throttle butterfly and advance the ignition timing a small amount which helps on a cold start...pull the choke on fully and try what I've described..the engine should at least "chuff" within 4 pulls..when it "chuffs".push the choke off and it should start on the next pull...it'll rev up much higher than it needs to , so be prepared to reduce the rpms to allow the motor to warm up some before reducing the rpms to a shift level

 

[boydog40]

yes sir I understand that and I am doing that with no success. think ill pull the carb and see if I missed something there
thanks

 

[boydog40]

update, feel so stupid, the cap on the fuel tank is not venting, unscrewed the cap she fired right off!! keep it simple!