78 Merc Thunderbolt starting problems

[Ben.Skelton]

Chapter 1: Long story short... missed the summer opener because when I launched my motor would not turn over... just a click. So I spent a few hrs and thought I had figured it out... I figured it was the solenoid. My battery was charged. I can jumper directly from the battery to the starter and it cranks like no tomorrow.

Chapter 2: Bought a new solenoid... figured cheap fix. Still the same problem. I tested voltage... OK. Not getting any voltage to the start pole on the solenoid. Not sure how to test the ignition switch but assume that is my next step. Here is the wiring schematic of my motor/ controls.


Chapter 3: You tell me... please help.

 

[mr 88]

Re: 78 Merc Thunderbolt starting problems

Just had the same problem turned out to be a bad connection at the engine plug.Brand new harness so that was the last place I looked.Replaced the ign switch [ NAPA ] and took the starter motor apart.Put it all back together and nothing.Friend hit the key and I wiggled the connector,vroom vroom.You could also have a break in the wiring harness.I believe to test the ign switch a test light will work.Hit the key and see if test light lights at the solenoid. You might be able to stick the test light into the wiring harness and see if you are getting juice there as well.Could of kicked myself for not checking the plug as I was in the water a couple times when it acted up.Eventually contact was made and she fired.