I replaced the impeller on my 1998 25 hp mercury tiller recently. Took it out this past weekend and noticed that when i was in neutral, the motor would idle really high. Also noticed the motor shifted hard into forward or backward usually jerking me a bit in my seat. Everything seemed to be fine other than that though. Any ideas what this could be?
I’d follow the throttle cable to the carb, make sure the cable is not jammed open a bit with the throttle handle let off all the way. If not, might need to clean the carb.
sounds like it may be running lean,underneath and behind the carb there should be two little hoses connected to the reed plate.
one of those may be cracked/broken and allowing the engine to suck air causing the lean condition.
if you dont see any hoses cracked or something blocking the throttle linkage keeping it at high idle,make sure the carbs idle speed screw is setting against the idle stop when the handle is rotated to full idle.
if that looks right an upper or lower crankshaft seal may have failed allowing it run lean as well.
The jerking is probably from the high idle itself. Kinda like dumping the clutch on a manual transmission.
Did you have the cowl off when you were working on the motor??
If so, maybe you bumped/bent the carb linkage/cable when you put it back on???
On second thought, since your shifter is probably tied into the throttle on that motor, I’ll bet you are misaligned with the shift linkage.
Take the lower unit back off and find neutral with it, and make sure your throttle/shifter is set in neutral/idle, then put it back together.
If you need help with the process feel free to PM me and I’d be glad to help.
On second thought, since your shifter is probably tied into the throttle on that motor, I’ll bet you are misaligned with the shift linkage.
Take the lower unit back off and find neutral with it, and make sure your throttle/shifter is set in neutral/idle, then put it back together.
This ^^^^^ improper assembly, just redo as above and everything should go back to the way it was before in regards to your idle RPM’s.
How exactly do i find neutral? Jist a feel thing on the shifter rod?
Pm sent, but I’ll post it here too so it may help others.
……..
You’ll see a little splined circle on the top of the lower unit, close to the water pump.
That’s basically the shifter. Turning it one way puts it into forward, turning the opposite way goes into neutral, turning it more the same way goes into reverse
You’re trying to find the middle (neutral) selection.
To check this, hold the main long shaft coming out with your hand (resistance to keep it from spinning). Spin the prop both directions with your other hand.
If the shaft spins, it’s in gear. Move the gear selector on the lower unit left or right, until spinning the prop no longer spins the shaft going to the motor (make sure to have a grip on the shaft to provide resistance).
Once the prop spins freely without spinning the shaft, you should be in neutral.
Next, take the cowling off the motor. You’re looking to have the motor/handle linkage in idle too.
Twist your handle/throttle left and right and watch the arm on the carburetor. Going left should pull on the throttle linkage (like giving it gas in reverse), and going to the right will pull on the linkage (like giving it gas in forward).
Find the middle spot between left and right where it isn’t advancing the carburetor. This should be your idle spot, and where you want it when you reassemble the motor.
Put it all back together and either run it on muffs or in a big tote of water to double check, and you should be all set )
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