1972 merc 80hp no spark

[bcspanky]

have 1972 80 hp mercury no spark motor turns over will not fire, internal wires don't look to good may need replacing .

 

[Laddies]

Re: 1972 merc 80hp no spark

Here's a simply test for the ign system.

 

[Moody Blue]

Re: 1972 merc 80hp no spark

I bought 3 of those motors last summer and the wiring in all three were shot. If yours is like mine you will have to redo all the wiring from the main plug. The insulation becomes very brittle and just falls off the wire leaving them exposed.

Watch for possible shorts between wires and between wires and ground.

 

[bcspanky]

Re: 1972 merc 80hp no spark

Hi can I just replace the wires one at a time or do or should I try to find a harness the that motor.Also should I use any wire or try to stick with the right color and gauge wire and do the make oil resistace wire. Thanks Bob

 

[Moody Blue]

Re: 1972 merc 80hp no spark

I've repaired my own but if you watch e-bay, you can find factory harnesses available for about $100.

If you choose to repair, try to maintain color codes as close as possible. It will help you re-connect correctly and trouble shoot down the road if the colors are maintained.

Don't reduce wire sizes. Its OK to go a little heavier wire (smaller number ie 16ga is heavier than 18ga) but keep in mind that the heavier the wire the more inflexible it will be.

I removed the entire harness then cut back all wires to within a couple inches of the plug. Insulation here was still good. I then spliced new wires to the existing stubs using heatshrink self-sealing crimp terminals. I then wrapped the whole bundle in double walled heatshrink tubing that I filled with black silicone then shrunk closed. Absolutely waterproof.
Took me a few hours start to finish.

 

[rtpassini]

Re: 1972 merc 80hp no spark

i just redid mine. with the help of moody and others. haha.
i bought my wire kit from...surplus unlimited i belive.

havent tried firing up but im praying!