1970 7.5 Mercury Fuel/Ignition Problems??

[allenb24]

Hi there i am hoping for some help troubleshooting my Merc outboard. On the lake last year my motor would cut out on me. I was able to limp it back to shore by feathering the choke back and forth. What would cause this, bad gas, bad ignition parts, wiring? Also I have looked in the Sticky Files for parts for this year and I am having trouble finding what I need. I would like to replace the electrical wiring as they look to be corroded and cracked. Any part numbers for this and diagrams? Before this happened the motor was a running dream and I was very impressed.

Serial number 2955816

Thanks for the help I would really appreciate it.

Brad

 

[mercuk]

Re: 1970 7.5 Mercury Fuel/Ignition Problems??

Brad, the way you described the feathering of the choke seems to be a carb/fuel issue to me. If the wiring is cracked that opens up a whole new can of worms lol...

Replacing the stator on these is not cheap, but it depends on how bad the wiring really is. If it were me, I would strip down the carb carfefully, counting the number of turns on needle ( ie winding it in slowly until gently seated and noting how any turns until seated i.e 1 and 1/4 turns) check float height (1/4") and blast all jets etc out with carb or brake cleaner.
Renew fuel pump diaphram ( prob not even 15$)

-Fresh fuel

- Check you got a nice spark on both cylinders.

- Good compression on both cylinders ( 120+psi on each +/- 5 psi)

If you done all of that correctly, I would say from and economical point of view, you have done all you can, without spending mega bucks on relacing expensive components like stators and coils etc.

Good luck

 

[Beek14]

Re: 1970 7.5 Mercury Fuel/Ignition Problems??

Couldn't have said it any better. Besides the wiring, the immediate problem definitely lies within the carburetor given the info you provided. Take it apart and clean it. Rebuild it if needed.