!989 Cannon Connector for 5.7 260HP Problems

[Canuckohio]

I have an 89 Sundancer 300 with twin 5.7 Mercs. The engine harness on the starboard side is essentially connected to the engine with a Cannon connector ( like a large plug in) located at the top of the engine. Recently, it cuts out the engine. If I move the cannon harness a bit the connection is made again. Is this a common problem and what is the right fix for it?
Thanks

 

[mistercomputerman]

If you are refeering to the 10 pin round connector for the engine harness, take the hose clamp off, pull it apart, take a knife blade or small screwdriver and GENTLY pry the split pins apart.

The pins are split and sometimes over time they squeeze together causing connectivity issues.

 

[Canuckohio]

Thanks for the tip...I had already done that earlier in the year,thinking that would take care of the problem...it didn't. I am thinking of replacing about the last three feet of harness before it gets to the connector...I have a feeling that I may have a broken wire in the harness, or perhaps where it enters the connector. And of course, the harnesses are not available now in any case (1989 model). Sure hope I can find a harness somewhere...any ideas?

 

[Cocktail Time]

New harness for my 95' 5.7 was about $175 from merc. Before I bought one, I had similar issues to what you are describing and tried spreading the connectors as described above. No luck. What I found was that there is a clamp that mounts to a bolt on the manilfold that holds the wiring loom away from the engine. Somehow over the years someone smashed that clamp down and it pinched a couple of wires in that loom. As a temp solution I jumped the crimped wire (red to ignition switch) directly to the starter. It fixed the issue until we replaced the motor and then the whole loom. If you need a cheap fix or just to keep going until you tackle the whole thing, I would try this method. I'm no wiz with a tester but it only took about thirty minutes to test the wires and another thirty to bypass and isolate the damaged section of wires.

Do you need a wiring diagram for the connector and harness? I would assume they would be the same as what I have. Also if you want to test the half of the harness from the dash to the engine, if you have enough slack try swapping that end of the harness from the other engine? Unfortunately Merc only sells the complete harness so you have to buy the whole thing even if you only need one side or the other.

Good luck!

Dan