1974 merc 1150 idle adjust

[rphillips]

My buddy's old boat starts & runs fine, but idles at appx. 1300 rpm. It idled fine till he had a non professional (shade tree) mechanic work on a fuel pump problem, pump problem fixed, but now excessive idle speed. We found the idle adjust screw, at the dist., & started backing it off. The idle speed started dropping, after appx. 1 1/2 turns the rpm had dropped to appx. 1100 rpm., all good, going in the right direction. kept backing the screw out farther, but the rpm quit falling. The idle adjust screw has lost contact with the stop on the dist. We have backed the screw out another 1 1/2 turns, but idle is still at 1100 rpm. I can grab the dist, with hand, & turn it backwards till stop on dist. hits the idle adjust screw & idle drops to appx. 900 rpm., seems real good, but if I turn the dist. loose, the dist turns back forward, losing contact with the stop adj. screw & the rpm goes back up to 1100 rpm. It seems there is a spring pulling the dist back forward. What am I missing, I don't see what is keeping the dist. from turning back freely, so the stop rest against the idle adjust screw & the thing idles as it should.

 

[merc850]

You have to adjust the throttle cable brass barrel to push the arm backwards, then push the handle fwd and see if the dist stops at the "max spark adv." screw; then push it farther to the "throttle stop" screw and make sure that the throttles are full open. Don't let the carb shutters act as a stop; you might have to adjust the screw to prevent this. When you have these settings done, set the idle speed in the water and in F gear not on muffs.