STRANGE starting problem 78 35hp evinrude

[jkarr]

i took the boat out the other day, motor started great and ran fine except for a slight miss on top end. i figured plugs. i changed the plugs out. next trip, the strange part, i tried to start the motor and nothing. check all lines etc, everything looked fine. to ensure the motor had not seized up, i turned the fly wheel and the motor started up fine. this has occured several time, nothing, then turn the fly and fires up. however, that miss is getting progressively worse. not the plugs, they are new.
anyone have potential thoughts, its a new one on me.

 

[Joe Reeves]

Re: STRANGE starting problem 78 35hp evinrude

What is the compression of each cylinder?

With the s/plugs removed, the spark at ranking speed should jum a 7/16" gap with a strong blue lightning like flame.... a real SNAP! Does it? The 7/16' gap is important!

What plugs are you using.... Make, Type, What Gap?

You say "tried to start the motor and nothing", then you mention "turn the flywheel".

Are you saying that the electric starter does nothing and you're cranking the engine's flywheel with a rope to start it? Exactly what are you saying?

 

[JUSTINTIME]

Re: STRANGE starting problem 78 35hp evinrude

do u have a manual, u will need one to start testing thing

 

[tashasdaddy]

Re: STRANGE starting problem 78 35hp evinrude

clarify your statement, it's a little confusing, year of motor or model #. tiller or remote control, what exactly did you do to test it. you can see it we can't. you are our eyes. welcome to iboats, were here to help, the more you give us the better the advice.

 

[jkarr]

Re: STRANGE starting problem 78 35hp evinrude

let me get the details down here first and we can go from there. year 1978, evinrude 35hp. has remote steering and electric start. plugs are Champion L78V, flat no gap.

symptoms: i turn the key start and nothing. take the lid off the motor, hand turn the flywheel, hit the key and it fires right up. subsequent starts, it works fine most of the time, i dont have to do anything but hit the key start. then when running, it has a bad miss. friend thought it may be a coil breaking down under load or a dead spot on the stater.

 

[jtexas]

Re: STRANGE starting problem 78 35hp evinrude

"turn the key start and nothing" meaning no sound or motion at all? Starter motor don't spin? No "click" from the solenoid? Does pushing the key in activate the choke?

Turning the flywheel should have no effect on the cranking circuit. Maybe a wiring fault?

 

[jkarr]

Re: STRANGE starting problem 78 35hp evinrude

correct, nothing happens at all, pushing the key in for choke does nothing either, no engage of the starter. then i hand turn the fly wheel and it will start up. sometimes it takes a couple of tries. if it had not been for me checking to see if it was locked up, never would have put it together to get it started at all.

 

[jtexas]

Re: STRANGE starting problem 78 35hp evinrude

Then neither the starter solenoid nor the choke solenoid are getting power. The flywheel has nothing to do with the either. The starter solenoid post where the positive battery cable is connected, has another red wire attached which carries 12V through the big red wiring harness plug to the keyswitch; the starter and choke solenoids are energized through wires running back from the keyswitch through that same plug.

My guess is that red wire (which has an inline fuse holder by the way) has a fault, and when you turn the flywheel you are coincidentally moving it a bit and allowing it to conduct. Maybe some corrosion at the fuse holder, or might be some chafed insulation where the bare wire can contact the engine block causing a short circuit.

I can't think of a way it would be related to your hi-speed misfire - but somebody else here might.

good luck

 

[jkarr]

Re: STRANGE starting problem 78 35hp evinrude

Thanks, i'll give that a look and see, get a meter on it to see if there may be a break or something there.