Cracked ignition coil

[bkwalker42]

I've got a '75 evinrude 70 horse. It has 104 psi on all 3 cylinders and a good (7/16) spark on all three too. I noticed a hairline crack on one of the coils yesterday. When you try to open it up out on the water it reaches full throttle for just a few seconds the bogs down. Could this coil cause that or is it something different? Any advice would be greatly appreciated!

 

[ddwilson]

Re: Cracked ignition coil

If it has a crack in it I would probably replace it, may not be the problem but will be soon. If it will idle fine but bogs down at speed sounds like more of a fuel delivery problem. Might check the fuel pump, filter.
Doug

 

[boobie]

Re: Cracked ignition coil

I vote for a fuel problem.

 

[bkwalker42]

Re: Cracked ignition coil

Sorry for such a late response.. I tested the fuel pump and its pumping great.. I cant seem to come up with a solution.. any more suggestions?

 

[Fed]

Re: Cracked ignition coil

Check for closed/blocked/partially blocked fuel tank breather.

 

[bkwalker42]

Re: Cracked ignition coil

A buddy told me that too. I tried it with the gas cap off, but still no difference. Would that be adequate ventilation?

 

[Fed]

Re: Cracked ignition coil

Run it off a small portable tank complete with hose, primer & connector.
A cheap way to eliminate all fuel problems prior to the motor.

(Gas cap off proves it's not the vent blocked)

 

[bkwalker42]

Re: Cracked ignition coil

Could it be a bad rebuild in the carbs?

 

[metriccrescentwrench]

Re: Cracked ignition coil

Could it be a bad rebuild in the carbs?

Yes. Just one example of something that could cause this would be a bit of debris in a carb's float valve, or a float valve that's not opening fully. That would allow enough fuel to flow for lower speed running but it couldn't keep up at full throttle.

I tested the fuel pump and its pumping great..

How'd you test it?

 

[kodibass]

Re: Cracked ignition coil

Run it at night with the cover off look for any arcs jumping, look at all your hose connections / clamps for cracks, leaks etc. when it bogs does the hose primer go flat? get a small portable tank have it raised so as to gravity feed the carbs come up to speed see if anything changes. replace the cracked coil or at least JB-Weld the crack see if it improves. New gas-fresh-gas-goooood gas. double make sure!

 

[bkwalker42]

Re: Cracked ignition coil

I hooked up some clear hose on the carb side of the pump and cranked the engine. it had a nice steady flow coming out if it.