Johnson Engine Electrical Help

[Tourtney]

Hi everyone, i have a 1970 60 hp johnson. The engine is having trouble cranking. The starter just seems to spin. Today i replaced both battery cables, including replacing the positive cable all the way to the plug to no avail. I also spliced connections and cleaned others. I have two main points. It did seem to help.

1. The rectifier appears to drop the voltage from around 12.7 tp 12.4 as well as dropping the current .5 amps or so. Bad rectifier?

2. I am now able to get the starter to engage the flywheel by normally connecting the positive cable to the battery and instead grounding the negative to the motor itself ( not the negative battery cable).

I replaced the negative wire connection and cleaned the area but it didnt seem to help. I think tommorow i am going to replace parts of the starter wire. What do you all think?

 

[F_R]

1. The rectifier has nothing to do with starting, other than keeping the battery charged while running. But you are going to blow the rectifier if you aren't careful messing with those battery cables. You can also blow that $$$ expensive ignition amplifier. NEVER run or attempt to start it with poor or no battery connections.

2. Sorry, you lost me with your description. But you seem to know what a voltage drop is. So do voltage drop tests across all parts of the high amperage (starting) circuit.

 

[racerone]

Have to agree with post # 2-----You can spend big $$$$ in a hurry if you are guessing.

 

[Tourtney]

2. If i run a jumper cable from the negative battery post and the positive post is run normally through the control box. The starter spins up.

Its funny you mention blowing the amplifier. Mine is making a ticking noise constantly when votage is applied. It seems that the only big volatge drop is through the rectifier. Yes, on my particular boat the wire from the rectifier mets on the battery top post of the solenoid and goes to the key switch. I know this because the voltage going to the solenoid to start is about the same as what is on the top of the solenoid. Also did a continuity check to be sure. Any test for the amplifier yo see if it is bad? That would cost a fortune...

 

[Tourtney]

Ok i replaced the positive battery wire all the way to the engine plug as well as the ground wire. Still not engaging flywheel, but seems to be spinning up a little now.next i will replace the bare ground wires that look corroded the braided ones that hook into the engine block directly. I belive it is a ground issue