115 2+2 High Idle

[adamschuh79]

Put the boat in the water today. Motor ran great for about 3 minutes. Running at wot and the motor died like it ran out of fuel. Would only restart using the choke. I was able to keep it running by choking occasionally and running at about 3k rpm. Continued to do that to get back to the dock. Now when I start the engine the rpm will not go below 1800. Thoughts? Brand new carbs last spring and ran great on the muffs in the yard this morning for 10 minutes.

 

[adamschuh79]

Put the boat in the water today. Motor ran great for about 3 minutes. Running at wot and the motor died like it ran out of fuel. Would only restart using the choke. I was able to keep it running by choking occasionally and running at about 3k rpm. Continued to do that to get back to the dock. Now when I start the engine the rpm will not go below 1800. Thoughts? Brand new carbs last spring and ran great on the muffs in the yard this morning for 10 minutes.

One more thing, the engine seems to be smoking much more than normal when running now.

 

[racerone]

Curious as to why new carburetors were needed.------Smoke could mean a carburetor float valve is not working.-----Enricher ( choke as some call it ) is stuck open.---Fuel pump diaphragm is ruptured.-----Not hard to sort out.

 

[adamschuh79]

Carbs were replaced because I was having issues with one not working correctly. Was able to get a fully rebuilt set for like 300. I let the engine cool off for a while, restarted and smoke is less now but running really high yet. A ruptured fuel pump diaphragm would cause the high idle?

 

[racerone]

A ruptured diaphragm would cause more smoke.-----A ruptured diaphragm would NOT cause high idle

 

[adamschuh79]

A ruptured diaphragm would cause more smoke.-----A ruptured diaphragm would NOT cause high idle

That's what I thought. I'm thinking an air leak somewhere. Unfortunately that might mean a trip to the shop.

 

[flyingscott]

Get a manual for that motor. Did you do the link and sync with the new carbs? Carbs on the right pistons? Throttle cable tight? Accelerator pumps set correctly? Not leaking. $300 seems cheap for a set of rebuilds. Are the carbs off a small bore or big bore motor? Is your motor a small bore or big bore? Compression test done? Serial # and yr of your motor.

 

[adamschuh79]

Get a manual for that motor. Did you do the link and sync with the new carbs? Carbs on the right pistons? Throttle cable tight? Accelerator pumps set correctly? Not leaking. $300 seems cheap for a set of rebuilds. Are the carbs off a small bore or big bore motor? Is your motor a small bore or big bore? Compression test done? Serial # and yr of your motor.

I have the manual. I did the link and sync, Carbs are all on the correct pistons. I did this Carb swap a year ago, had no issues at all last season. This problem developed this spring after a year of no issues with the new carbs. The motor is a 1988.

 

[racerone]

Check flywheel key.------Is throttle arm against idle stop ?-----Carburetors all closed at idle ?

 

[adamschuh79]

Check flywheel key.------Is throttle arm against idle stop ?-----Carburetors all closed at idle ?

View attachment 20230409_122407.mp4

 

[adamschuh79]

View attachment 377405

Throttle arm is against stop, carbs are closed. I need to pull the flywheel yet but thought a quick video would help.

 

[adamschuh79]

Throttle arm is against stop, carbs are closed. I need to pull the flywheel yet but thought a quick video would help.

View attachment 20230409_122420.mp4

 

[adamschuh79]

View attachment 377406

This video I pulled the timing arm towards the front of the engine. Seems to be way out of time to me.

 

[racerone]

If the flywheel key is sheared the timing will be way out of spec.----I do not believe a timing light can determine this.

 

[adamschuh79]

If the flywheel key is sheared the timing will be way out of spec.----I do not believe a timing light can determine this.

Does this sound to you like the timing is way off? I'm thinking if I had an intake air leak, the engine would run smoother, just idle really high.

 

[racerone]

I cannot touch your motor.----But in my opinion it should be easy to figure out and fix !

 

[adamschuh79]

I cannot touch your motor.----But in my opinion it should be easy to figure out and fix !

I'm waiting for a strap wrench to arrive to hold the flywheel. I decided to check the timing with a timing light tonight. At my current idle speed of roughly 2000 rpm the timing is at 4 degrees after top center. So obviously it's quite a bit off. I will pull the flywheel and see what I find.

 

[adamschuh79]

Today I pulled the flywheel off, the key is intact with no damage. I also checked the trigger, as the CDI Electronics troubleshooting guide says to check the trigger if you cannot get the idle RPM below 1500. The trigger ohms out correctly.
I was really hoping to find a sheared key, not sure what could be the issue now.

 

[adamschuh79]

Okay, I finally got a little time to investigate further tonight. I pulled the resonator cover off to check the carb synchronization and immediately found the problem. Sticking out of carb #2 was the straw from a fogging oil can. It was holding the butterfly open. I removed it and she purrs like a kitten again.
The sad part is, I remember last fall losing the straw into the resonator when I was fogging the engine. Lesson learned! Check the simple things first!

 

[Texasmark]

Okay, I finally got a little time to investigate further tonight. I pulled the resonator cover off to check the carb synchronization and immediately found the problem. Sticking out of carb #2 was the straw from a fogging oil can. It was holding the butterfly open. I removed it and she purrs like a kitten again.
The sad part is, I remember last fall losing the straw into the resonator when I was fogging the engine. Lesson learned! Check the simple things first!

Great news. Never know what you'll find troubleshooting equipment!