1972 Evinrude 85 hp puzzle

[confused mechanic]

i have a 72 erude 85 electric shift. the problem is starting it. it rolls good but wont quite fire. now here is where you will scratch your head a while. if you unhook the no 1 plug wire, it will be running b/4 you can release the switch.will take any and all advice. my handle says it all. i have talked to several boat mechanics and I either havent found one old enough to be familiar with this or it is a freak occurance. I need help as my 14 y/o son wants to go tubing. thanks

 

[Daviet]

Re: 1972 Evinrude 85 hp puzzle

Just a couple of thoughts.
Are the plug wires on the correct plugs, blown head gasket between #1 & #3?
Has anyone had the dist cap and wires off of the engine? Has it always done this or did it just start?

 

[confused mechanic]

Re: 1972 Evinrude 85 hp puzzle

points were set at .010, rotor cleaned, cap checked. changed spark amp and same result. tried to check compression. tester was funky but appear all cylinders about same. pulled #3 plug and did not start. will only start with #1 plug unhooked. as i said, it is puzzling. i've done my share of wrenching but this one is making me lose sleep

 

[confused mechanic]

Re: 1972 Evinrude 85 hp puzzle

found the cause finally. cleaned the cap with sand paper and reinstalled it. after trying to start it and getting it running with no.1 unhooked again, i removed distributor cap again. found a slight carbon spot on one end of pickup bar on #1 lead.was firing to it from #4. had a used cap from another motor, installed and it runs fine. thanks for the help.

 

[Daviet]

Re: 1972 Evinrude 85 hp puzzle

Glad you found your problem, thanks for posting your repairs, will probably help someone in the future.