Help with 1970 9.8 model 110

[Gusman]

Hello all, this is my first post. I registered to this forum due to the fact that most of my google searches on mercury 9.8 hp model 110's led me to this site. But I have not been able to find anything that is directly related to my issue. So hopefully you all can steer me in the right direction, sounds like there are a lot of knowledgable people on this site!

Here is my issue:
Recently I was given a 1970, 9.8 mercury 110. Not in bad shape, but I had to replace the fuel lines as well as change out some old wiring. The owner said that he had never used it as he got it from his wifes father when he died.

After replacing the fuel lines, wires, and water pump impeller I tried to start it in a trashcan full of water. On the second pull it started, but is reving at a very high idle and I cannot throttle it down without it cutting off... Is this a carborator issue? or something else? Should I start with changing spark plugs and cleaning carborator? If so, what is the safest way to do so without damaging engine?

I am not a mechanic, just mechanically inclined, and this is my first outboard that I have tried to restore. Any help on the direction that I should take would be much appreciated.

Thanks!

 

[green4themoney]

Re: Help with 1970 9.8 model 110

hey, i have the exact same engine haha... i had some problems i wound up having a bad coil so it was intermittenly running on one cylinder, have you cleaned the carb yet? maybe try that with some new plugs and c how she does

 

[Gusman]

Re: Help with 1970 9.8 model 110

Thanks, I will try the plug thing today....is there a way to clean the carb without taking it apart? Can you safely spray carb cleaner while engine is running? or should I just bite the bullet and take the carb out and clean it? And, is it difficult?

 

[green4themoney]

Re: Help with 1970 9.8 model 110

try the plugs first, always start with the simplest possible problem, if that doesnt cure your problem, your better off to take your carb off and clean it, i had to do it with mine as well, its not too hard to take it off, or clean it for that matter you have to take the bolt off that connects the choke linkage to the carb,and the 2 nuts on each side from the carb to the intake, its a little tricky but a small adjustable does the trick, you also want to take your fuel pump off and get it out of the way (just makes accessing the carb that much easier) and you will have to take the top cap off from the pump to the carb make sure your fuel filter is 'a ok', then take the top cap off the side bowl and take the float out and you can use some carb cleaner to spray in there then blow out every orfice you can find with the air compressor, you will see various nuts at the bottom of the carbs,you take these off and you will be opening up some jets that can also use cleaning, if you believe you will have doubt on where the parts will go back together, take pictures before you take each part apart, it helps considerably... sounds like thats all you need though.... give that a try and get back to me!

 

[green4themoney]

Re: Help with 1970 9.8 model 110

here is an exploded diagram of the parts from your tillotson side bowl carburator, you can look at that will help you with cleaning and re-assembly

http://www.crowleymarine.com/mercury_parts/453/4.cfm

 

[Gusman]

Re: Help with 1970 9.8 model 110

Thank you! I will remove carb and try this as I attempted the spark plugs and issue is still there. I believe that there is some sort of port open allowing too much fuel in the carb and hopefully a good cleaning will set this straight. Thanks for your replies and for the diagram!

 

[green4themoney]

Re: Help with 1970 9.8 model 110

right on, try the cleaning then get back to me, and remember te spark plugs are NGK# buhw-2

 

[green4themoney]

Re: Help with 1970 9.8 model 110

i have also failed to mention to re-adjust your idle screw, you screw it in untill it seats itself, then back out 1 to 1 and a half turns.....

 

[green4themoney]

Re: Help with 1970 9.8 model 110

the idle screw is number 35 on the diagram i sent you by the way

 

[dajohnson53]

Re: Help with 1970 9.8 model 110

For what it's worth, I used a Seloc manual for a couple of 9.8's in that era (one was pre-1970... 68 or so; current engine is 1974). It was accurate and worked well for rebuilding the fuel pump (EASY) and disassembling, cleaning and reassembling the carb (also easy, but first time was tricky... I recommend the full soak-clean procedure and rebuild kit).

I now have a factory manual, and it is better, but the Seloc is OK for the carb work if that's what you can get your hands on. I actually look at both when I am trying something new, but the factory manual is the "go to" book.

The problems I had with my current engine were similar. Even after the fuel pump and carb rebuild, I couldn't get a smooth low RPM idle, I was dropping a cylinder due to bad spark. I traced it to the coil, replaced it and it helped.... but then the problem became intermittent. I then was more methodical and figured out it was the switchbox. Both are easy DIY parts installation, but that switchbox was very expensive. The coil, not too bad. Runs like new now.

 

[green4themoney]

Re: Help with 1970 9.8 model 110

i had the exact same problem with my 1970 9.8.... bad coil, it would intermittanly run on one cylinder but i swapped coils now runs like new, thank god for us, on our engines we dont have the CD with the trigger and the switchbox system, we just have the "phase maker" system with points, its a decent ignition system, but a bit of a pain tracing out where you might have problems... once the motors get this old the wires definately need a little bit of TLC if not replacement

 

[Gusman]

Re: Help with 1970 9.8 model 110

Just wanted to say thank you for all your help. I took the carb off, dissasembled and cleaned real good with carb cleaner. Put it back together today and reinstalled. It runs great! With a little adjustment, it idles great and goes through the whole range of throttle. I love it!

 

[green4themoney]

Re: Help with 1970 9.8 model 110

glad to hear it! enjoy, these are great engines, dam near bullet proof if maintained properly