1976 15 hp evnrude

[Jon123]

Im back on here hoping you guys can help me out again I really appreciated. I tore down my motor and replace the base head EXHAUST gasket and reseal my crank case halves and now my motors not running the same anymore. At home it idles like a champ, goes into gears and run flawlessly in a "barrel", but when its on the lake it would go full throttle about 10 yards or so and putters then shuts off. The motor would start again and idles fine in neutral but when its at full throttle it would take off and died. It did this to me 7 or 8 times then the motor wouldnt start anymore. Good thing I had my trolling motor or eles I wouldve had to row back. =)

The top cylinder is about 89 and bottom is 90 psi cold compression testing. I also gap my points to .20. I rebuild my carb last month aready and the gas is all brand new with gas stablizer. The motor ran great last weeked before i took it apart to replace top mounting joints inside the head.
Any help would be greatly appreciated thanks.

 

[OptsyEagle]

Re: 1976 15 hp evnrude

Have you tried it with the hood off. Perhaps you have an exhaust gas leak. At idle she gets enough air but at higher throttles she starves out. Removing the hood will determine that.

The other thing that series of motor prefers are NGK spark plugs as opposed to the recommended Champions. NGK B6HS or B7HS work much better then the UL81C from Champion.

I assume you set the slow speed adjust on the carb correctly and you linked and sync'd the carb to the throttle cam's timing advance?

 

[Jon123]

Re: 1976 15 hp evnrude

Have you tried it with the hood off. Perhaps you have an exhaust gas leak. At idle she gets enough air but at higher throttles she starves out. Removing the hood will determine that.

The other thing that series of motor prefers are NGK spark plugs as opposed to the recommended Champions. NGK B6HS or B7HS work much better then the UL81C from Champion.

I assume you set the slow speed adjust on the carb correctly and you linked and sync'd the carb to the throttle cam's timing advance?

I just had it in the barrel again today and it would start right up but when I rev it at full throttle it died out and wouldnt want to start anymore. I recheck the compression when the engine was warm and it was giving me some funny readings though. The top plug was at 115 and bottom was still at 90. But when I recheck the top plug again it drop back down to 90 and stayed there. So I decided to recheck the bottom plug again just to make sure it didnt change and it was fine at 90, now there both back at 90 psi. I didnt try running at full throttle with the hood off because it wouldnt start anymore.

The engine idles fine and trolls fine at idle speed so I think maybe the slow speed needle screw is about right were it should be. I have not did the link and synch yet. Is it important, do i need to do it?



thanks OpstyEagle =)