1974 7.5hp mercury wont start!!

[fishinwithmercury32]

I have a 1974 mercury 7.5hp motor that im having some trouble with. The motor was running last october and I took it out a couple of times then, but over time it just quit turning over. I just replaced the ignition and kill switch wires. They were corroded and mangled so i thought this may be the issue; I made sure that the wires were grounded and connected properly, but im still not getting any spark when I connect the spark plug to the wire and pull the crank.

I guess my question is why am I not getting any spark? Or if I am, should I be seeing a spark when I connect the unscrewed plug. I have good compression, new wires, and new spark plugs. What am I doing wrong? Thanks for reading.

 

[fishinwithmercury32]

Re: 1974 7.5hp mercury wont start!!

Sorry, Also some numbers on the motor 837-2756 with the name Kierraefer.

Thanks,

 

[fishinwithmercury32]

Re: 1974 7.5hp mercury wont start!!

Sorry, Also some numbers on the motor 837-2756 with the name Kierraefer.

Thanks,

I found the serial number. It is 3275803. 1972.

 

[slate1234]

Re: 1974 7.5hp mercury wont start!!

hi did you find out why you had no spark I have the same problem on 1976 7.5 mercury any help I am greatfull for
Thanks Paul

 

[walter227]

Re: 1974 7.5hp mercury wont start!!

hi did you find out why you had no spark I have the same problem on 1976 7.5 mercury any help I am greatfull for
Thanks Paul

Just repaired a 1974 , and a 1975 (both mercury 7.5 hp) In both cases the wiring from the switchbox was faulty.

 

[mercuk]

Re: 1974 7.5hp mercury wont start!!

Just repaired a 1974 , and a 1975 (both mercury 7.5 hp) In both cases the wiring from the switchbox was faulty.

Had the same thing happen to me. Them switch boxes seem to be quite weak.....

 

[walter227]

Re: 1974 7.5hp mercury wont start!!

Had the same thing happen to me. Them switch boxes seem to be quite weak.....

The switchbox itself is usually ok , it`s the wiring coming out of them. A few people on here have successfully "rebuilt" the unit simply by changing the wires then refilling the cavity with clear kitchen silicone..we forget that some switchboxes are well over 30 years old !

The technology at it`s inception was state of the art , these motors are a strong reliable motor that do not miss a beat

 

[slate1234]

Re: 1974 7.5hp mercury wont start!!

sorry I didnt get mine running it is in a out building in my garden I really did my head in sorry I cant be any help