Idles too fast after replacing flywheel shear pin

[johnbuoy44]

120 johnson (1991), replaced flywheel shear pin (was sheared), now when engine is started it seems to idle correctly while it is still cold. after it warms up the idle rpms go up to 2000-2400. What did I miss in replacing shear pin? What else could it be?

 

[steelespike]

Note the position of the throttle plate in the carb.There is also a link and sync that assures the carb opens and close at the precise point.
Idle should be about 700. May be as simple as adjusting the idle speed screw.

 

[emdsapmgr]

That engine has the Quickstart feature. When the engine is cold (under 92 degrees) and is started, the timing is advanced in order to help it's cold-running attributes. This can result in a somewhat higher idle rpm. (just a couple of hundred rpm.) As soon as the engine warms up to 93 degrees, the spark advance retards to normal timing, and the idle rpms' will drop to normal. Your engine seems to be running just the opposite. Unlikely it's a Quickstart problem. I'd probably check the idle timing degrees on the flywheel on #1 and #2 cyls with a timing light-to see what is going on. That may tell you something, esp if the key sheared again and the idle timing is way off.

 

[Faztbullet]

It will idle higher on a hose than in water, on a hose idle will be 1000-1200rpm and in water it will be around 850-950rpn and 700rpm in water in gear.

 

[johnbuoy44]

That engine has the Quickstart feature. When the engine is cold (under 92 degrees) and is started, the timing is advanced in order to help it's cold-running attributes. This can result in a somewhat higher idle rpm. (just a couple of hundred rpm.) As soon as the engine warms up to 93 degrees, the spark advance retards to normal timing, and the idle rpms' will drop to normal. Your engine seems to be running just the opposite. Unlikely it's a Quickstart problem. I'd probably check the idle timing degrees on the flywheel on #1 and #2 cyls with a timing light-to see what is going on. That may tell you something, esp if the key sheared again and the idle timing is way off.

As further info; I had replaced the power pack before I had determined the shear pin was toast. I have always started the engine with the water ears before going to dock as this motor has always been a bear to get started (have since determined that the electric primer is not working correctly and leaking fuel around the manual primer knob). Before the shear pin problem the boat would idle correctly in the 700-1100 rpm range for as long as I would let it warm-up. I have went back to the original power pack with the same problem of excessive high idle speed in the 2000-2400 rpm range after it runs for 2-3 minutes. The throttle plates remain in the idle position when this happens. It appears to be getting fuel input from some where some how. Could the fuel side of the VRO contribute to this? The idle stop adjustment makes no difference. This problem has me buffaloed. All help greatly appreciated

 

[johnbuoy44]

As further info; I had replaced the power pack before I had determined the shear pin was toast. I have always started the engine with the water ears before going to dock as this motor has always been a bear to get started (have since determined that the electric primer is not working correctly and leaking fuel around the manual primer knob). Before the shear pin problem the boat would idle correctly in the 700-1100 rpm range for as long as I would let it warm-up. I have went back to the original power pack with the same problem of excessive high idle speed in the 2000-2400 rpm range after it runs for 2-3 minutes. The throttle plates remain in the idle position when this happens. It appears to be getting fuel input from some where some how. Could the fuel side of the VRO contribute to this? The idle stop adjustment makes no difference. This problem has me buffaloed. All help greatly appreciated

 

[johnbuoy44]

As further info; I had replaced the power pack before I had determined the shear pin was toast. I have always started the engine with the water ears before going to dock as this motor has always been a bear to get started (have since determined that the electric primer is not working correctly and leaking fuel around the manual primer knob). Before the shear pin problem the boat would idle correctly in the 700-1100 rpm range for as long as I would let it warm-up. I have went back to the original power pack with the same problem of excessive high idle speed in the 2000-2400 rpm range after it runs for 2-3 minutes. The throttle plates remain in the idle position when this happens. It appears to be getting fuel input from some where some how. Could the fuel side of the VRO contribute to this? The idle stop adjustment makes no difference. This problem has me buffaloed. All help greatly appreciated