1977 Mercury 1500 inline 6 motor with distributor.

[jasestieglitz]

High I’m new to this forum and would really like some help if possible. I have a 1977 Mercury 1500 in line 6 motor with a distributor. The last time I was able to run it in the lake it worked great until I headed back to the boat landing. I was full speed on a plane and went to throttle down and my throttle was stiff. I had to force it into neutral because my boat wasn’t slowing down. When I would put the boat in neutral the motor would return to idle for a minute then it would completely take off. Continuing to throttle up with out me touching the throttle. I got the boat out of the water and looked under the hood. What I found was that my cables were free but my distributor was not turning all the way back to idle like it did before… it is completely stuck and will not return back to the original idle position. I’ve tried turning the distributor back to idle and starting the motor but that doesn’t work. I completely have no throttle control. Any help
Would be appreciated. I posted a video showing what the distributor is doing. It doesn’t return to idle which is up against the set screw unless I make it. When you hold the distributor back it doesn’t return to idle when the motor is started. I have no throttle control but it continues to throttle up.

 

[racerone]

I would look for a broken spring in the upper part of the distributor.

 

[merc850]

Remove the throttle cable from the arm that activates the distributor and see if ti moves freely; if not then the grease in the distributor adapter has probably hardened or is too heavy; if it does move correctly then the cable or the control box is at fault.

 

[GA_Boater]

The spring Racer is talking about is item 4. Seeing Merc850 beat me, so do as he suggests. Grease tends to harden and between items 1 and 6.

A word of caution - The rotor can't removed from the shaft. It's one piece and expensive. In fact, all the parts are expensive, so use care.

 

[merc850]

The spring Racer is talking about is item 4. Seeing Merc850 beat me, so do as he suggests. Grease tends to harden and between items 1 and 6.

A word of caution - The rotor can't removed from the shaft. It's one piece and expensive. In fact, all the parts are expensive, so use care.

View attachment 353507

I used a heavy grease in mine and when it was cold (less than 60*) it wouldn't advance enough to start, I replaced the grease with 2-4-C.

 

[jasestieglitz]

Remove the throttle cable from the arm that activates the distributor and see if ti moves freely; if not then the grease in the distributor adapter has probably hardened or is too heavy; if it does move correctly then the cable or the control box is at fault.
View attachment 353501

I have already checked cables. First thing I checked because it was simple. There were just installed ( brand new) and were moving properly.

 

[GA_Boater]

I have already checked cables. First thing I checked because it was simple. There were just installed ( brand new) and were moving properly.

While the cable was off, did you try rotating the distributor? If you turn it some and release, the spring should snap the distributor back to the home or idle position.

 

[jasestieglitz]

While the cable was off, did you try rotating the distributor? If you turn it some and release, the spring should snap the distributor back to the home or idle position.

That’s what I’m saying is that the distributor is not snapping back to home/ the idle position. Even when you hold the distributor at the home position it doesn’t change the throttle at all. The motor keeps taking off . I can not figure out why it did that. I was full speed and backed off and the motor wanted to keep going. I have completely no throttle control. Even with the cables disconnected.

 

[merc850]

I think that the throttle cable pushes the dist. to the idle stop and is adjusted by turning the brass barrel while in neutral.
Push the bottom of the throttle lever to the back of the motor until the distributor hits the "idle speed" stop then look into the carb and see if all the throttle shutter(s) are closed; then pull on the throttle arm and see if the shutter(s) open. The distributor hits the "max spark adv." first then keeps opening the shutters until the plate hits the " throttle stop" screw, this is full throttle. Make sure all the plates are opening all the way and simultaneously.

 

[jasestieglitz]

All carb shutters are closed and open like they are suppose to. The problem is the distributor will not return back to its Idle position. Even with the cables disconnected. I Checked carb shutters at first to make sure they were not stuck open but they are completely closed. But the motor will still take off with no throttle control. There is nothing I can do to make the motor idle because something has happened to the distributor. That much I can confirm. I am away from then or until this weekend. I can try and post a video showing what’s going on when the motor is started.

 

[Chris1956]

Throttle cable must push the throttle closed. Adjust the barrel nut until it does, with a little preload.

if she still runs too fast at idle, you can back off the "idle stop" set screw. It is located above the distributor. You will then again need to adjust the throttle cable to push the throttle closed.

You want about 850-900RPM in neutral.

Do not adjust any of the other set screws, without a timing light and detailed link and synch instructions.

 

[jasestieglitz]

The problem is the motor was idling fine. Went on the lake and the motor wouldn’t idle any more it will only run like it’s at full speed. I can’t adjust said idle screw because the distributor won’t rotate and return back to its idle position against the idle screw.I never adjusted anything I was riding on the lake tried to slow down to approach the dock at the boat landing and motor wouldn’t slow down. I had to force it neutral. Took the cover off and the distributor wouldn’t rotate back to idle. That’s all I know I haven’t touched anything else on the motor to cause this problem. Also checked throttle cables that’s not the problem either

 

[racerone]

Repair as required I would think.----Not that hard.-----Mark / check belt timing and remove distributor.

 

[Chris1956]

That motor will have 2 zerk fittings on the distributor rotation linkage. Have they been lubed?

If the distributor won't rotate (make sure it isn't against the stop), likely something solid got into the rotation sleeve. I have never seen this, so it is a guess, likely a SWAG.

 

[jasestieglitz]

That motor will have 2 zerk fittings on the distributor rotation linkage. Have they been lubed?

If the distributor won't rotate (make sure it isn't against the stop), likely something solid got into the rotation sleeve. I have never seen this, so it is a guess, likely a SWAG.

Yeah it’s not against the stop but I will have to clean around it there is some junk and particles.