1986 Mercury 35hp Throttle/Spark Advance issue

[ToBrokeforNew]

Hello, I have a question about my 1986 Mercury 35hp Outboard. My issue is that my throttle linkage will not return to idle after accelerating. So for example, if I shift into forward go WOT and then come back to neutral the RPMs are still raised. I took the cover off and the motor and saw that the linkage was about 3/8'' to 1/4'' from the idle stop screw. In trying to diagnose the issue I disconnected the Throttle cable from the linkage. I then manually moved the linkage to WOT and let go to see if it would return to the idle stop but it wouldn't spring back. So my question is what causes the linkage to spring back to Idle, and what would cause this issue in the first place? I have found an entire used Throttle/Spark advance linkage used online and am going to purchase it anyway because of severe cracks in the plastic around the adjustment screws. Any input on this matter would be much appreciated.

 

[Chris1956]

The throttle itself is pushed back to idle by the throttle cable. The throttle cable should push the throttle arm against the stop, with some preload.

However, the carbs have their own spring to close them. That is where you need to look.

 

[ToBrokeforNew]

The throttle itself is pushed back to idle by the throttle cable. The throttle cable should push the throttle arm against the stop, with some preload.

However, the carbs have their own spring to close them. That is where you need to look.

Okay so if the throttle cable is disconnected should the linkage move back to idle on its own? The spring on the carb is not that strong to move the whole linkage by itself with the cable disconnected correct?

 

[cyclops222]

Is the carburetor throttle shaft sticky ? Linkage AND spring both removed ?

 

[Chris1956]

It is likely that the throttle arm will not move back to idle on it's own. The throttle cable is adjusted to push the throttle closed, and a bit of preload is added to help the operator feel neutral.

The carb spring is only designed to close the throttle plate, not move the whole linkage, trigger etc.

 

[ToBrokeforNew]

It is likely that the throttle arm will not move back to idle on it's own. The throttle cable is adjusted to push the throttle closed, and a bit of preload is added to help the operator feel neutral.

The carb spring is only designed to close the throttle plate, not move the whole linkage, trigger etc.

Okay, on the throttle cable, I have the adjustment barrel as far as it will go IE the thaft with the threads is fully exposed and I can't increase the stroke of the cable any further. I didn't mention it previously but I have replaced both the Shift/Throttle cables with new ones. I have checked the shaft and stroke lengths of both the new and old cables and they are identical, with the adjustment barrel fully unscrewed I can't give any more length to the stroke of the cable which in turn is not allowing the carb butterfly to fully close. It's a 2 Gen Teleflex cable and I don't think they make longer or shorter shafts for the year of my motor to my knowledge, any suggestions?

 

[ToBrokeforNew]

Is the carburetor throttle shaft sticky ? Linkage AND spring both removed ?

No sir, I just rebuilt the carb and the butterfly plate will spring back to the closed/idle position freely. The reason I have asked about the Throttle arm on the motor springing back to idle is that I have seen videos of people with my exact year of motor manually revving the motor using the throttle arm with the Throttle cable disconnected and the arm retracted back to idle with no assistance. I was under the impression that there is a spring somewhere on or attached to the linkage that causes it to retract the arm back idle. I have reviewed all the schematics of the throttle/spark advance but could not find any spring with an exception for the spring for the Spark advance.

 

[cyclops222]

Are any cable clamps missing on either end of the cables ? All 4 ends are normally CLAMPED in place to prevent your problem.

 

[ToBrokeforNew]

Are any cable clamps missing on either end of the cables ? All 4 ends are normally CLAMPED in place to prevent your problem.

No, I have 2 sets of clamps one set in the controller itself the other is in the front of the motor and all are in working condition. I have noticed that there is a slight bit of slop of maybe 3/8'' from the initial movement in the forward direction till the cables move the throttle. So I backed off the adjustment barrel to hopefully remove the slope but I was unsuccessful.

 

[Chris1956]

It sounds like some part of the throttle linkage at the motor is mis-adjusted. I am not familiar with your motor exactly but look for adjustments from the throttle arm to the carbs. There are often stainless steel rods that have some threads. You will want to lengthen those to push the throttle arm against the throttle cable. I did not see anything obvious on the diagram.

THROTTLE AND SPARK ADVANCE LINKAGE - 1986 Outboard 35 [ELPTO] 1035726 | Crowley Marine

View parts diagrams and shop online for THROTTLE AND SPARK ADVANCE LINKAGE parts, 1986 Outboard 35 [ELPTO] 1035726. Offering discount prices on OEM parts for over 50 years. FAST $4.95 shipping available.

www.crowleymarine.com

 

[ToBrokeforNew]

It sounds like some part of the throttle linkage at the motor is mis-adjusted. I am not familiar with your motor exactly but look for adjustments from the throttle arm to the carbs. There are often stainless steel rods that have some threads. You will want to lengthen those to push the throttle arm against the throttle cable. I did not see anything obvious on the diagram.

THROTTLE AND SPARK ADVANCE LINKAGE - 1986 Outboard 35 [ELPTO] 1035726 | Crowley Marine

View parts diagrams and shop online for THROTTLE AND SPARK ADVANCE LINKAGE parts, 1986 Outboard 35 [ELPTO] 1035726. Offering discount prices on OEM parts for over 50 years. FAST $4.95 shipping available.

www.crowleymarine.com

I feel the same way, there has to be one of the adjustment screws that's not set right. I will dig a little deeper into the culprit. I bought the Haines manual but to be honest, out of the 400-plus pages of the service manual about 20 pages are dedicated to my specific motor and it's all timing and not related to my issue. I appreciate your input and will give an update whenever I come to a conclusion.

 

[Chris1956]

Hanes manuals are not very good. Seloc and Climer are usually worse. A Mercury service manual is what you need.

 

[cyclops222]

Read post 1 again. Sure looks like torn apart flex cable or bushing has fallen off of the throttle shaft of the carb .