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2003 Johnson 50 not firing on cylinder 2

Scott.k

New member
Hello. I'm working on a j50plstd for a friend. The engine only runs on cyl 1. Have replaced plugs, wires, vro pump, rebuilt carbs, new tank, hose and primer bulb, rebuilt primer solenoid.

Every now and then it will run an both cylinders for a little bit, but usually only cylinder 1 fires. This is all at idle on the garden hose. Doesn't run well enough to put in the lake.

Have verified good spark and ignition timing on both cylinders. Compression is at 130 on both cylinders. Verified throttle/ignition timing synchronization with factory shop manual. Verified spark and timing on both cylinders with timing light , spark tester and by shocking the crap out of myself on both cylinders with engine running and pulling plug wires off.

Im at a loss here. Thinking maybe reed valve or lower crank seal? I looked at the reed valves when the carbs were off and didn't see anything that looked bad. But that was looking at them from the carb side only. And I did notice a different sound from the reed valves when turning the engine by hand with the carbs off and the plugs out. The top cyl and bottom cyl had a noticeably different sound from the reeds.

Also have verified crankshaft is not out of phase by checking when cyl 1 is at tdc, cyl 2 is at bdc and vise versa.

Any tips or hints of what to try/test Next? I am a mechanic, but an auto mechanic. So outboards are not my usual projects.

My friend and I would greatly appreciate any help. Thanks!
 
Remove cylinder head.-----Inspect position of sleeves.-------Bring each piston to TDC.----Then push piston to BDC and listen for crankcase compression.
 
Tank some fuel in squirt bottle and spray in carb..if it pick up and runs recheck carb..

Did what you said and man do I feel stupid! Took the carbs back off and #2 carb float was installed up side down!

Running on both cylinders now...on the hose. Will try in the lake tomorrow. Will update...
 
One more thing. The engine wants to "sneeze" when cold. Manual says this indicates a lean condition. Mixture screws are 6 full turns out. Never seen any 2 stroke needing 6 turns out? Used to more like 1.5 to 2.5 turns out on mixture screw...

If I lean the mixture (screws in) it sneezes worse. Is that normal for this engine? Service manual does not give a base setting.
 
Testing on muffs or in a barrel? Have to have backpressure to adjust correctly. Also plastic top cover can warp if overtightened causing air leak..
 
I was running it on muffs at first. Put it in the lake yesterday and it seems to be running good now. Hopefully it stays that way for a while.

Thanks for the help guys! I feel pretty stupid for installing that float upside down, but at least it wasn't anything more serious.
 
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