Throttle linkage/minor surge

[andywehrle]

Ranger 33, electronic ignition, electric fuel pump. Two related problems I think.

Engine has been running fine. Today, engine started fine, idled well, but at about 1650-1700 rpm two things happened. The throttle would no longer advance the engine rpm. I could advance the throttle but the engine rpm remained at about 1700 rpm. I could reduce rpm but not increase beyond 1700 rpm. So I'm thinking throttle linkage.

The other problem is a minor engine surge - no more than 2 or 3 hundred rpm - not enough to affect speed - but enough to put your teeth on edge wondering if the problem would get worse or the engine die. Engine didn't die, motored in with no major incident, just worried it in all the way.

Not sure if the two are related, but they showed up on the same outing. Engine has run strong before this.

Thanks for any help you might be able to provide.

[Marian Claire]

Welcome. I feel that a 2-3 hundred change in RPMs is a rather large change. When running at 1650-1700 rpms does the engine surge up? First thought is crud in the carb. Try removing the drain in the bowl and flush some fuel thru. Then you could remove the main jet and clean it. Fixed or adjustable? Or just pull the carb and clean it. Would be a good idea to have a new gasket ready if you pull the carb.
Do you have a way to monitor fuel flow to the carb? A fluctuation in fuel pressure or flow could indicate a clogged filter or a failing fuel pump.
Also pull one of the plug wires when running at 1700 and see if it improves. That would indicate a blocked exhaust system.
When checking the linkage pay close attention to the last/throttle shaft connection. Keep us posted. Dan S/V Marian Claire