115 Johnson Shuts Off At Full Throttle

[kayiamunre]

I Have A 1990 115 Johnson That I Recently Replaced Due To Pre-Ignition On The #1 Cylinder. With No Shutting Off Issues. Prior To This I Had A Full Tune Up Done It. My Boat Was Completely Rewired From Bow To Stern With Vro Wiring Removed Because It Wasn't Being Used And To Reduce Wiring Clutter, I had The Lower Unit Inspected And Fluid Change, Water Pump, Fuel Pump, New Fuel Line (Ethonal Rated), Carbs Cleaned And New Gasket Kit Installed, Spark Plugs/Wires, New CDI Control Box, New Prop. My First Trip Out On The Water I Lost 1 Cylinder. All That work Sat For A Year And Then I Had A New Powerhead Installed. I Had New Head Gaskets, New Reed Valves Put In The Carbs, New Fuel Water Seperator, Spark Plugs/ Wires(again) I Didn't Think I Should Have Replaced All Those Other Parts Again Being I Only Had About 2 Hrs. On Them. My Compression On The Engine Was Decent 105 On 3 Cylinders And 100 +- 2. So I Took The Boat Out After I Got The New Powerhead Installed. She Ran Decent For A Powerhead That Was sitting Up For A While. I Sat For A While, Getting Ready To Go My Battery Was Dead. Got A New Battery Went Out The Next Week Boat Cranked Fine Took Off Reached Full Throttle It Purred Like A Kitten. Got Ready To Move To Another Location. Reached Full Throttle It Ran For About 2 Min Strong. Then It Shut Off Like I Turned The Key Off. Pulled The Hood Everything Was Normal. Hit The Key It Fired Up No Hesitation. Started At Idle Back To The Dock (1Mile or so) Reached 1/2 Throttle No Problem 3/4 No Problem, Full Throttle It Started To Shut off Pulled The Throttle Back No Problem. Took it Back Mechanic Said I Needed A New Stator. Had A New Stator, Rectifier, Coils, Wires/ Plugs (Again). He Said That Why It Shut Off Low Spark Got It Back In The Water Hit The Throttle She Ran Like A Deer. No Problems. Then It Shut Off Like I Turned The Key Off. Idled Back To Dock. Now I've Spent So Much Money I Don't Know What To Do Next. Please Help Me Tell What I Missed. Maybe I Should Change The Fuel Pump. Please Help Before My Wife Pulls The Plug!!!!!! Thanks

 

[ondarvr]

Re: 115 Johnson Shuts Off At Full Throttle

Fuel related bogging or quitting tends to be a slowing down of the motor until it finally stops or reaches an RPM where it will still run.

Electrical issues tend to shut the motor off, or at least some of the cylinders, like a light switch. This may be a total shut down, sporadic or totally related to RPMs.

If you think it's electrical, put timing light on it and bring up to the range where it stops and see if there is a spark issue (do this on the water).
This will tell you if you're correct. A shorted wire, poor ground, or maybe the power pack would be next.

Your Motor also has a slow mode, if it senses a problem with the temperature or oil level it can slow the motor down to below a certain RPM.

 

[kayiamunre]

Re: 115 Johnson Shuts Off At Full Throttle

Could A Bad Temp Sensor Cause The Overheating Sensor To Go Off And Make The The Motor Shut Off As Well.