1977 evinrude 115hp electrical help please

[madbiker]

my problem is this. my motor is a 4 cylinder 2 and 2. passenger side 2 cylinders are firing driver side 2 cylinders are not. i swap the coils over and all coils work on the passenger side but none of tem work on drivers side. i was told that meant bad power pack so i bought a new one. the problem is still there with the new power pack. i thought maybe the stator went bad but i was told if the stator is bad there will be no fire at all.

the motor is a 1977 evinrude 115hp
top end was rebuilt last year ran very well until this,any and all help will be greatly welcomed

 

[iwombat]

Re: 1977 evinrude 115hp electrical help please

It could very well be your timer base. If you have a spark tester you can check this pretty easily. Switch the leads from the timer base around as they connect to the power pack. Swap 1->2 and 3->4 if the other side now fires you need to either adjust or replace your timer base.

DO NOT try and run the motor with the leads swapped. All spark plugs out and spark tester only.

 

[madbiker]

Re: 1977 evinrude 115hp electrical help please

could the adjustment get off without anyone messing with it? i will try to swap the wires to see if the firing moves to the other side to test the timing base. what about the stator? if it is bad does it mean you get no fire at all? i know very little about boats, just enough to get me in trouble.

 

[madbiker]

Re: 1977 evinrude 115hp electrical help please

could it be a timing issue? something as simple as the timing being off? or is it more that just that?

 

[madbiker]

Re: 1977 evinrude 115hp electrical help please

ok i swapped wires as you said and i still have same thing, fire on same side as before and no fire on other side. i am at a loss any other idea? thanks

 

[iwombat]

Re: 1977 evinrude 115hp electrical help please

Well, that would seem to eliminate the timer base, and since the power pack is new I think that's probably not your problem either (although it still could be). Next check the grounds on the coil bracket. There should be a grounding strap on both sides. Also, check the grounds where the coils are mounted and make sure they are clean.

When you swapped coils did you keep the coils and wires as a unit?

 

[F_R]

Re: 1977 evinrude 115hp electrical help please

could the adjustment get off without anyone messing with it? i will try to swap the wires to see if the firing moves to the other side to test the timing base. what about the stator? if it is bad does it mean you get no fire at all? i know very little about boats, just enough to get me in trouble.

There is only one capacitor in the power pack. There is only one stator to charge that capacitor. So, a bad stator wouldn't charge it at all and you wouldn't have any spark at all.

There are four SCRs in the power pack, turned on and off by two sensors on the timer base according to polarity. As the proper SCR is turned on, the capacitor is discharged through the correct coil. So, common sense says you have a bad power pack or bad sensors (timer base), or a wiring problem with the sensors. Disclaimer: Common sense is true, but something can come along to fool you.

This is where it pays to have the proper test equipment. Otherwise, you can guess till you get lucky.

EDIT: Is this "no fire" problem at cranking speed or while running? Weak stators and/or weak sensors can indeed produce erratic spark. So can slow cranking speed. It has to be cranking at about 300 RPM to get reliable spark. Try it with the plugs out so it cranks faster (as a diagnostic tool). Some of those things that I mentioned that can fool you.

 

[madbiker]

Re: 1977 evinrude 115hp electrical help please

hey i didnt see your replies till late today but here is the latest news. talked to a local mechanic today told him my delima he said it was a weak stator so i hunted everywhere to find one here. put the new stator on and same problem. when i swapped the coils over it was wires and coils as a unit and yes the grounds are all clean and good. so now i have checked all coils and they are good i have new plugs, new power pack and new stator but still no fire to number 1 and 3 cylinder cranking or running. i am at a loss here seems to me only thing i have not replaced is timing base.

 

[D.spencer]

Re: 1977 evinrude 115hp electrical help please

Are you sure it is actually a no spark issue on the one side or is what you are saying based on there is no drop in rpm's when plug wires are pulled with the engine running? The ignition may actually be ok but there is some other problem- crankcase leak ( kinda like a vacuum leak)-fuel-compression-valves- other. Sounds to me like the ignition is ok if the all the coils will work on the one side. I would bet most likely the intake plate gasket has sucked in due to bolts not being torqued properly if the power head was recently replaced but that is just a best guess.

 

[madbiker]

Re: 1977 evinrude 115hp electrical help please

no there is no spark at all cranking idling or running on cylinders 1 and 3

 

[F_R]

Re: 1977 evinrude 115hp electrical help please

no there is no spark at all cranking idling or running on cylinders 1 and 3

As you said, the only thing left is the timer base & sensors.

 

[iwombat]

Re: 1977 evinrude 115hp electrical help please

That particular timer base is adjustable, you just have to break the epoxy on the adjustment screws. To properly space it you need the special tool. That being said, I've got three and ALL, from the factory, were adjusted quite a ways out. One was out so far as to create the condition you describe. But switching the leads also changed the problem.

 

[madbiker]

Re: 1977 evinrude 115hp electrical help please

turns out is was that stator but the battery was to weak to get the proper rpms to get all the fire we needed. all is good now and i am headed for the river. thanks to you all for the advice and help. well i am back and the boat ran awesome thanks again fella's.