1975 johnson 40hp model 40EL75 engine runs 10mins full throttle cuts off

[fittyyamaha]

Will a defective (kill switch part 386696) cause engine cut off after 10min run at full throttle
Hard to restart even pump fuel bulb and choke.I think electrical cause runs about same time
everytime then shuts off.It did not do this until a put in new (driver coil part 0763810).I had
a problem cut off switch in past but cause only one cylider to cut out it had bad diaphram I
replaced it for a fix .I thinking the new coil get hot and ground out BUT before I chng it again
need know if cut out switch will kill engine at full throttle after 10min run.Any help appreciated:grumpy
NEW points .condensors. driver coil .both cylinder coils near head .fuel pump assy.carb kit rebuild.spark plugs .magneto plate

 

[Daviet]

Re: 1975 johnson 40hp model 40EL75 engine runs 10mins full throttle cuts off

Have you checked to see if you actually loose spark when it quits.
In my experience with kill switches is that they either work or they don't.
Why did you replace the driver coil in the first place?

 

[fittyyamaha]

Re: 1975 johnson 40hp model 40EL75 engine runs 10mins full throttle cuts off

Have you checked to see if you actually loose spark when it quits.
In my experience with kill switches is that they either work or they don't.
Why did you replace the driver coil in the first place?

Had intermentent skip sometimes 5min apart sometime 15min or more apart 2 coils on powerhead were good.That problem was too much play magneto plate at brass bearing cause irratic point clearance .That is now fixed.I will hook timing light to a plug next time see if loose sparK at shut off both cylinders.

 

[fittyyamaha]

Re: 1975 johnson 40hp model 40EL75 engine runs 10mins full throttle cuts off

Took a timing light with me.Engine shut off checked and had firing both plugs.I hooked up a complete new OMC fuel line and new 6gal
tank and went out again to test .That was a fix,it ran perfect.It was the fuel line,between tank connector and the fuel primer bulb was a piece of debris (came from defective fuel connector at 6gal tank end) causing intermittent shut off.Thanks for you help.