1977 Mercury 1150 Throttle Adjustment/Tuning

[mercman65]

I got my 115 merc all hooked up to the boat started right up on the first try after sitting all winter. The problem is with the throttle response. Shift lever works ok and shifts all 3 positions smoothly but the throttle doesnt seem right. The warm up lever doesnt move anything until it is almost all the way up. When the motor is running and I raise the lever there is no response, until thirty seconds to a minute later. It slowly revs up then takes off like a bat out of hell all the sudden. Im assuming something is binding up with the distributor? Not sure how to make the adjustments to get better response from the lever/cables. They move smoothly when they are not hooked up to anything. If any body could provide detailed instructions on how to adjust/tune the throttle i would really appreciate it. thank you

 

[Chris1956]

Re: 1977 Mercury 1150 Throttle Adjustment/Tuning

Obviously it shouldn't do that. Remove the wrap cowl and the top cowl. Inspect the linkage from the throttle arm to the distributor for play. Now look at the fingers on the distributor that open the carb. Maybe the plastic cover fell off the fingers?

Have someone lift the cold start lever and see if the throttle arm moves a bit. If it does, the cable is likely adjusted properly. You want the throttle cable to be adjusted to push the carbs closed, with a bit of preload, but no more than that.

 

[mercman65]

Re: 1977 Mercury 1150 Throttle Adjustment/Tuning

The carbs open and close just fine when not connected. Im pretty sure the problem is with the throttle stop and the idle stop. Im just not sure how they are suppose to be set and the procedure for putting them in the correct position. I appreciate any help you can give.

 

[Chris1956]

Re: 1977 Mercury 1150 Throttle Adjustment/Tuning

Throttle stop is set easily. Open throttle stop all the way. Now open throttle until carbs are wide open and distributor is fully advanced. Now turn throttle stop until it contacts distributor. Turn it 1/8 turn more and lock it down. The throttle stop is supposed to protect the carbs from being forced more open than they are capable of.

Idle stop is simply the sped of the idle in neutral. Normally after you set the carb idle mixture, you set the idle stop to give enough RPM to idle in gear, and allow smooth shifts w/o grinding. idle speed is about 1000RPM in neutral and 850 or so in gear.

Do you have the idle pickup timing and max spark advance set properly?

 

[DaFuzz]

Re: 1977 Mercury 1150 Throttle Adjustment/Tuning

Is there any way someone can either post pics of these different adjustment screws or post a link to a thread or something explaining timing/idle stop/etc adjustments with pictures? I'm working on some of the same issues as mercman except mine is a 78 900 but i assume most of these adjustments are similar or the same. Thanks in advance for any help.

 

[Chris1956]

Re: 1977 Mercury 1150 Throttle Adjustment/Tuning

You might like to get an OEM Service Manual. Link and synch is a bit complicated to explain, and manual has pictures.