Dies under heavy throttle, ignition failure?

[christians89]

My 97 40hp evinrude will bog/dies only under heavy throttle usually after its been running for a couple of minutes and sometimes after first cranking. I am thinking its a weak coil or power pack but was wanting a second opinion. Also does anyone know of a good way to test these parts? I am sure its not fuel related, pushing choke does nothing but kill it more. Thanks for all help!

 

[christians89]

Re: Dies under heavy throttle, ignition failure?

Also could it be the S.L.O.W feture getting me??

 

[cr2k]

Re: Dies under heavy throttle, ignition failure?

Have you tried squeezing the primer bulb when accelerating? Could be fuel pump.
Oh yea is the tank vent open?

 

[christians89]

Re: Dies under heavy throttle, ignition failure?

Yes, and yes, tried both with no avail. I feel sure its not fuel related too much of an "on off" feeling while this is going on, also just went through the carbs and cleaned tank not long ago. Any other ideas?

 

[archcycle]

Re: Dies under heavy throttle, ignition failure?

Also could it be the S.L.O.W feture getting me??

If it is SLOW then it shouldn't be dying on you. The ignition components perform differently once they heat up so you may be experiencing some failure due to that.

Pull off the coils and check if the epoxy potting on the backs of them look all cracked or burned. Then carefully check the wires going to the coils and to the cylinders for physical problems. Coils would be a fine place to start as they are cheap and won't require you to buy any extra tools or devices.

 

[christians89]

Re: Dies under heavy throttle, ignition failure?

I have checked the plug wires and they appear to be in good shape. Ill pull the coils off next time I get a chance. Does anyone know the ohm spec for them?

 

[tx1961whaler]

Re: Dies under heavy throttle, ignition failure?

First things first, so you don't have to guess.
What is the compression on each of the cylinders?
Have you performed a spark test with a spark tester? It should jump a 7/16" gap on the tester.

 

[christians89]

Re: Dies under heavy throttle, ignition failure?

No I have not done a compression test but it starts way too easily and runs way too good (when the problem isnt occurring) for it to be low compression. I have not performed a spark test with a tester however I have simply pulled the plugs to check for spark. I will do that next.