70hp mercury does not work at all rpm

[RaScLeS]

full throttle is faster than ever but I cant let off smoothly, the rpm is not what it once was smooth all the way across but it will cruise at the rpm it wants to.

I put a new used switchbox serial 7778-A1 on my 1979 motor today and it fixed it and had it go past 5000rpm, idle, and run well. (put new plugs in same time)

ive replaced it all, stator, trigger, switchbox, cleaned carbs, everything I can think of that goes wrong.

the gas wasnt brand new but all the motors around here ran flawless on stuff thats much older.

any idea's that I can try in the spring would be great.

the motor will not smoothly run across all rpm, it hesitates at wot and takes off, and crusing speed is determined by the motor and not my throttle

help all I can think of is that time will make it better since its only ran a few hours over the last year or so, an hour on the water might help

 

[jeffersondodson561]

Re: 70hp mercury does not work at all rpm

Have you checked throttle cable smoothness. Slowly move cable to WOT and watch throttle cam. I had one situation where the throttle roller on the cam lost it's outer barrier/dampener. Not sure it would create your situation but could mess up the sync/link.

 

[RaScLeS]

Re: 70hp mercury does not work at all rpm

it had a fresh lync n sync a few times already haha because i had replaced the trigger then stator at separate times, I will double check its smoothness come spring.

I got a can of wynns engine tune up is that like seafoam ? i was thinking ill run something in it this spring since the motor has seen under 10 hours in probably 5 years

haha im still happy to see that my tach was over 5000 its been a while !!!