Engine sputtering

1

1972gt6

New member
We are experiencing a sputtering engine (Honda 90 4 stroke) and will stall when accelerating slowly. Does not happen when we gun the engine only slow acceleration. Spark plugs have been replaced, carburetors cleaned.
Suggestions??
 
1972gt6":1fiq6x9x said:
We did put new gas in, and replaced fuel filter. What about the primer bulb? Do we need to replace it?
Click to expand...

Be sure that it works, and that the fuel can flow freely through it.

There's a one-way check valve in it that can contribute to or become a point where debris accumulates and blocks/clogs up the smooth flow of gas upward by the fuel pump in the motor.

Everything from the carburetors to the fuel intake tubes in the bottom of the tanks has to be free to let fuel reach the engine, and needs to be checked out if you do indeed have a fuel flow problem.

Joe. :teeth :thup
 
I would guess either a carburetor synchronization issue, lean mixture screw(s), or there is still some varnish in the idle circuit of one or more carburetor. When you mash the throttle on your engine there is a rudimentary type of accelerator pump/dashpot that burps fuel out of the main metering tube by pushing air into the float bowl. If you accelerate slowly this does not happen and you may be leaning out as you open the throttle plates. There isn't enough fuel to keep up with the air.

It is almost impossible to clean the idle lift tubes without a ultrasonic cleaner like you would use with jewelry. Often times it is just easier to replace the tubes as you eliminate the possibility of missing a thin film of varnish that breaks loose later thus you are doing the job a second time.

Good luck,

Randy
 
fuel tank vents? maybe if they were clogged, the harder suction of gunning it could move the clog and pass air, but the slower rev up may kill the motor before moving the clog, just a guess
 
1972gt6":1zfi6jgu said:
We are experiencing a sputtering engine (Honda 90 4 stroke) and will stall when accelerating slowly. Does not happen when we gun the engine only slow acceleration. Spark plugs have been replaced, carburetors cleaned.
Suggestions??
Click to expand...

Doesn’t sound like a primer bulb if it only stalls when accelerating slowly, but runs fine when you gun it. Replacing the primer bulb could be the fix though, they seem to have a mind of their own when going bad.
Try dumping two cans of SeaFoam in a half full tank and see if that clears it up.
I put two cans of SeaFoam in my Starboard tank after every service and run that tank nearly dry before switching. In the spring both tanks get SeaFoam...and I always top of the tanks after each trip.


Good luck...

Jay
 
Sea Foam has a good reputation. One of our outboards was running poorly at low throttle settings and stalling at idle. A bottle of Chevron Techron additive cured it.
Dunno plugged orifices are 1972gt6's problem but sometimes you get lucky and and a little additive helps.
 
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