1988 Merc 70 HP wiring problems

[1988Merc70]

Bought a used Harris 'toon with a 1988 70 HP Merc. Drove it for about 4 hours and it started not wanting to start. Blowing the 20 AMP fuse and won't start at all. Installed a new key switch, installed a replacement starter and starter solenoid and lubed shift and throttle cables and the engine pivot point.

A Marine mechanic did some of the work and after it continued failing he recommended replacing the control box. However he had health concerns and bowed out. No other marine mechanic available to work on 37 year old Merc..

So I'm working on it, pulled the wiring harness and control box to test indoors, too cold outside to do anything. Plan to test all wires with jerry rigged light bulbs to find broken or shorted wires in the harness.

Question: Don't really need trim/tilt, toggle kill switch, tilt indicator, audible for low oil, light switch, etc. All we need is a starter switch and a choke (3 wires).

Can a guy run the motor without the 5 pin cable to the console, unplugged? Comments on blogs say the China made control boxes are not reliable. IF the wiring harness is failed can a new wiring setup be purchased?

We just need basic operations for use on a smaller lake in the Brainerd Minnesota area.

Thanks for any assistance.

Tim C.

 

[Chris1956]

Since the motor does not use any battery power to create spark, the blown fuse suggests a bad wiring harness or a short.
What is the condition of the wiring harness for the engine? A lot of them fail by now, if not replaced. Failing wiring harnesses can ruin the other igntion components.