1976 mercury 9.8 110 no middle middle speeds wont throttle up most of time?

Bassman86

Seaman Apprentice
Joined
Jul 16, 2013
Messages
31
i have a 1976 9.8hp 110 with the thunderbolt ignition. it is an electric/manual start model. i just got it and it is having some terrible running issues. first its a pain in the butt to start most of the time and second it is having throttle issues. it will idle decent but not real low when i go to increase throttle it will increase a little then stops increasing until i get to wot position in which it will kind of sputter or almost sound like its bogged down? sometimes it will end going wide open and run great but it seems to be all or nothing like there is no middle and most of the time no high speed. i checked the carb out and cleaned it properly, it does seem as thought the inlet needle for the float may stick a little even when completely clean. and the first time i took it out i noticed it would leak fuel from the bottom of the bowl i couldnt see if it was the screw in the bottom or seal between the bowl and carb. also even after running it i stop to fish and when i go to start it again its like trying to start it from ice cold again. im using the manual start as i am in the process of replacing the battery cables. another problem was i also noticed alot of the electrical wiring was corroded and broken so i replaced alot of the wiring and i think thats fixed. im gonna order a carb rebuild kit but im kind of lost here and any help would be greatly appreciated.
 

mfkadz

Petty Officer 2nd Class
Joined
May 26, 2015
Messages
135
I take it you just cleaned the carb and did not rebuild it. There are a few channels that run through the body of it. As part of the kit you should get new jets, gaskets, and a new float. the sticky float is an easy fix. The metal is soft and easy to adjust. Don't forget to make sure that the float is level when the fuel cuts off.

mike
 

Bassman86

Seaman Apprentice
Joined
Jul 16, 2013
Messages
31
i soaked it, sprayed it out and blew it out with compressed air then rinsed it. i was pretty confident that i had all the holes and channels cleaned out and i have the float adjusted correctly. you believe this is a carb problem im having? thanks
 

mfkadz

Petty Officer 2nd Class
Joined
May 26, 2015
Messages
135
Well, that sounds like a thorough cleaning.

This happens when you manually advance the throttle at the carb?
And the butterfly moves smoothly?

How's the timing? does the advance move smoothly? And can you see the change on the flywheel with the timing light?

mike
 

Bassman86

Seaman Apprentice
Joined
Jul 16, 2013
Messages
31
yes it happens when advancing the throttle any where. im not sure about the timing i thought the timing on this motor was something that ever needs or gets changed? im confident he flywheel was never even off it before i got it. my instinct makes me think its not getting the fuel and air it needs when it should be getting it. i dont know the exact details of how the carb works but is there something that opens or closes to cause mid and high range rpms? i guess i dont really know how throttle process works the firing speeding up and the fuel/air mix increasing but i guess the problem has to be in lines of that somewhere?
 

mfkadz

Petty Officer 2nd Class
Joined
May 26, 2015
Messages
135
There are 2 butterflies. One is the choke and is on the outside. The second controls the amount of air fuel get;s to the carb. When you operate the throttle it turns the butterfly deeper in the throat of the carb.

I was asking if all that moves smoothly, no hitches. And if you look down the throat you should see the butterfly move nicely and evenly.

mike
 

Bassman86

Seaman Apprentice
Joined
Jul 16, 2013
Messages
31
yup everything moves as it should.. from what i know anyways. nice and smooth. for some reason i feel like t a fuel/air problem as in carb but io cant understand how it didnt change at all after i removed and serviced the carb, i just got a complete carb rebuild kit for like 35$ it was a steal so im gonna do that when i get it, is it possible that the fuel pump isnt working properly or something? it weirds that itll run full once it gets there which is usually from me trying to get wot for about 10 min of giving it throttle and backing off a little etc.but no middle throttle at all. i dont understand what im missing?
 

mfkadz

Petty Officer 2nd Class
Joined
May 26, 2015
Messages
135
You should get all the little caps for the cleanout holes. If there are any. Make sure to pull those when cleaning.

mike
 

Bassman86

Seaman Apprentice
Joined
Jul 16, 2013
Messages
31
hmm.. i did see what i believe may be a cap like you said where would i get replacements
 

Bassman86

Seaman Apprentice
Joined
Jul 16, 2013
Messages
31
any else have any input on this or know where I can get the caps mentioned above
 

Bassman86

Seaman Apprentice
Joined
Jul 16, 2013
Messages
31
if so yes it is. how do the middle and high speed functions work? how does the carb add more fuel air and how does the motor fire faster maybe it's not getting the right fuel air when it needs it? or maybe it's not firing right? it seems to because it will eventually run wide-open but even then no middle speeds and even then only after trying to throttle up after about 5 to 10 min. any info is great..thanks
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,048
I see problems on these motors with old worn out crankshaft seals.------Top one is easy to inspect and in fact I see them pushed right out of the crankcase.-----Chipped reed valves on one I took apart a few weeks ago.-------Fourty year old motors need inspection and maintenance to run properly again.
 

Bassman86

Seaman Apprentice
Joined
Jul 16, 2013
Messages
31
and does replacing the reed valves and seals require the powerhead to come off and case to be split? after reading it sounds like it could be a cause for my kind of problem. and what kind of cost is associated with these parts.
 

mfkadz

Petty Officer 2nd Class
Joined
May 26, 2015
Messages
135
The reeds should be just under the carbs. They are usually on their own part. Unless Merc is different. Remove carbs should expose more bolts that hold on the reed assy. You might even see reed issues just looking in after the carbs are off.

mike
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,048
Reeds are internal on a reed block mounted around the crankshaft !!-------Powerhead needs to come off and apart to work on them.--------Powerhead need to come apart to replace the lower seal as well. !
 
Last edited:
Top