Re: 1975 johnson 85 horse starter problem
Start by ensuring that the battery is fully charged, and have it load tested. Then go over all connections, at the battery, ground, starter and solenoid, polish them to a shine then retighten. Check wiring for nicks, cuts, abrasions, or crunching when you flex it. That is a sure sign of corrosion, which would cause resistance in your starter circuit. The following test can help isolate a section or component of the starting circuit as well. Let us know what you find.
Voltage Drop Test
First set your DVM to the 20 Volt scale
Put your POS voltmeter lead on the battery POS terminal and the voltmeter NEG lead on the large incoming solenoid/battery terminal post and give her juice. If the meter reads more than .3 volts, the battery cable is bad, corroded or you have a faulty connection (loose).
Next, connect the POS lead to the incoming large solenoid post and the NEG lead to the outgoing large solenoid post while giving her juice. If the voltmeter reads greater than .2 volts, the solenoid is bad, corroded or has a faulty connection.
Next, connect the POS lead to the outgoing large solenoid post and the negative voltmeter lead to the starter positive post and give her juice. A reading of over .2 volts indicates faulty wiring between the solenoid and the starter.
Finally, connect the NEG lead to the NEG battery post and the POS lead to the engine block and crank the engine. A reading greater than .3 volts indicates a faulty negative cable, corrosion or a faulty connection.
