lean sneeze

[GLEN DEUTSCH]

I am restoring a Johnson 9r69s. 9.5 hp; 1969. I can’t get rid of the lean sneeze when running slow. Accellerates and runs fast. Pulling the choke out a little takes care of the problem. Squeezing the bulb does not help. I have cleaned the carb three times including removing the welch plugs. Tried using a different carb that I also cleaned. Float is adjusted appropriatly.New o ring on the slow speed needle valve where it enters the carb. Turning the slow speed valve to more rich has no effect. No leak in either crank shaft seal. Removing the powerhead is a big chore , so I am replacing the seals anyway. Fuel pump works good.Reed valves are light tight. New carb gasket snugged not too tight. Sprayed the powerhead with soapy water looking for a leak. I miust be overlooking something. Help!

[Buccaneer]

Disregard, I missed that you tried a different carb.

Prepare to be boarded!

• This reply was modified 5 years ago by Buccaneer.

[frankr]

Carb/spark synchronization correct?

[RICK EICHRODT]

I agree with Frank. Check your carb linkage to make sure when at idle, the throttle plate is fully closed! It has a weird roller, plate adjustment that is kind of awkward but once you get the hang of it, it simple.

[fleetwin]

Sounds like you tried a different carb which changed nothing, correct? Pretty much rules out carb issues….Except for carb synchronization…Are you sure the linkage is set up correctly and the butterfly is closing completely at idle? Just because the roller isn’t touch the carb linkage does not mean the butterfly is closing properly. Haven’t had too much experience with the 9.5s, but I do remember that cam/butterfly linkage is strange….Just like the rest of the engine I guess…I don’t know if there is a way to mess up the mag plate linkage on these engines that might cause the ignition timing to be overly retarded at idle/low speeds, check the throttle cam pickup setting.
I’m guessing you have just gotten this engine, but will ask if it ever ran OK for you? Sounds like you have already removed the powerhead and replaced both seals, I’m guessing that made no difference. You mention the reeds look OK, did you just peek at them or remove the leaf plate assembly? Remember there are two different intake gaskets, I’m not sure if it is possible to inadvertently swap them on this engine or not…If so, Using the carb gasket under the leaf plate assemble would create a crankcase leak between the two cylinders. A broken fuel pump diaphragm probably would have rendered the pump inoperative.
Any evidence of previous major work on this engine? Does it look like the crankcase has been split? New head gasket, or exhaust gaskets? Does it look like someone had been messing with the intake manifold?

[GLEN DEUTSCH]

Thanks for all the help. The reeds are OK. I took them out and held them to the light. Reed box and carb gaskets new. Does not look like it has been monkeyed with. The idea of the linkage gives me something to look at tomorrow. Thanks. Keep you posted.

[GLEN DEUTSCH]

Well, I think I fixed the carb and lean sneeze problem, but now another promblem arose. Put it on the water and now it idled a little better, but ran rough at high speed. I ran it in the test tank. Ran rough like one cyl. was intermitantly cutting out. Sure enough,when I pulled the top plug wire,nothing happened except it ran a little smoother. Stil some cutout but not as bad. Pulled the bottom and it shut off. Back to the shop. Put the spark tester on it and initially got good spark on the bottom wire. Reset the timing by very carefully setting the gap. Lightly filed the points (before I set them) and cleaned with a little lacquer thinner and blew dry with compresser. Put the spark tester and now get unreliable spark flom both plugs, intermittently. Sometimes they fire; sometimes not. No mag plate wobble. Mag plate grounded to block OK.
You will remember: I have switched coils. New condensers. New plug wires. Disconnected the kill switch at the points. New points. Used different spark testers to be sure my homemade one wasn’t the culprit . Tried setting the timing with a multimeter. It seems like, whenever I fix something, something else goes wrong. Must be something loose. Something I am over looking. It was running like a champ WOT, but coughed at idle. Recleaned the cab for about the sixth time and now this. I refuse to give up. Too much emotionally invested.

Glen

[fleetwin]

Sounds like all ignition components are new, correct? Perhaps coil or condenser leads are pinched or being hit by the flywheel….

[fleetwin]

Sounds like all ignition components are new, correct? Perhaps coil or condenser leads are pinched or being hit by the flywheel…. What did you do to get rid of the lean spit at idle?

[GLEN DEUTSCH]

Got rid of the lean sneeze by cleaning the cartb one more time. Sych is dead on.. I have to walk away from it for awhile. Go back at it next week. Thanks to all who helped. Will keep you posted.

Glen

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