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Mercury Controls and Range of Motion

D

Donewright

Regular Contributor
Greetings,

This is my first Gas powered boat. After three years of working on this in my spare time, I finally got it out on the lake.

The engine has a 1978 Powerhead and a 1989 Lower Unit. The controls are from the 1989 Powerhead that the last owner destroyed.

I thought I hooked up everything correctly, but what I didn't realize until getting out on the lake was that the controls rotate down to the floor. I know I saw this when attaching everything, I just didn't realize how wrong this must be until I tried to drive the boat.

The power curve was quite crappy, so I'm thinking I have an issue. When I watch the throttle mechanism on the engine, it appears that is is moving through it's range of motion, I mean the carbs appear open almost 100 percent when the control in pointed to the floor.

Should the controls rotate this far ????

 IMG_0002.jpg IMG_0003.jpg
 
Believe it or not, that's about right for those controls. The huge range of motion is necessary to do the F-N-R shifting.

Have you timed the motor with a timing light? Important!

Jeff
 
No I have not. I figure it must be off a bit, the power curve seems a bit sporadic. I did examine it again last night and I noticed that a vacuum line was interfering with the throttle roller and cam. So when I tried to reroute it it appeared to be brittle in spots and real squishy in other spots. So I replaced every line on the engine, about 9 feet in total. I was thinking perhaps I had a vacuum leak perhaps. Not sure, just trying to cover all my bases.

I read that a bad stator can cause power issues, but the voltage gauge went to almost 16 volts at about 3500 rpm's, so I think the stator is OK.

I have the original service manual, I'll see if I can find the timing procedure.
 
I found there was a gap between the throttle roller and the cam, this may have caused part of my mess. I'll start a new thread for the timing questions.

Thanks!
 
Stators normally do 2 things.-----One part of the windings charges the battery.----The other part provides voltage for the ignition system.-------The gap on the roller may be normal.-------Read your instructions carefully before making adustments.
 
Read the instructions and determined I just needed to re-sync the carbs. The roller is now touching the cam..

I checked the timing and it was near perfect. I made a huge discovery though!! I had lost spark at three cylinders. So I replaced the ignition modules and retested. I now have a strong spark at every cylinder now. The spark jumps 7/16" easily and makes a large cracking sound!

I think I may have solved my power/idle issue. I'll have to pull it out of the garage to test :)
 
lol, my ignition switch has gone bad .......................... well I manually choked the engine and jumped the solenoid and ba-bam ! It sounds a lot better then it used to.

Thanks for the tips guys!
 
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