Logo
FULL SITE MENU

1992 or 93 98 Mercury will not throttle up

W

wadeq

New member
"Greetings all,

I just pruc

"Greetings all,

I just pruchased a used Mercury 9.8 outboard that starts right up and idles fine, but it only throttles up about maybe half way! Where do I start first in troubleshooting or is this something that can be fixed without much headache? Thanks in advance for your help."
 
"Wade, post your serial number

"Wade, post your serial number. Merc stopped production of the 9.8's in 1985 - so you either have your hp wrong or someone gave you an incorrect year.

Once we figure out what you have we can determine a course of troubleshooting..."
 
"Thanks for responding Graham,

"Thanks for responding Graham, The serial # is 6563804 , the gentleman I bought it from said it was a 92 or 93 model. I appreciate you helping me figure out what I have. Starts fine, idles fine, only throttles up maybe half way. Thanks again!"
 
"That serial is for a 1984 mod

"That serial is for a 1984 model. The last 9.8's were built in 1985. Them and the 7.5's were essentially the same motor parts wise.

In 1986 Merc started their new line of 6/8/9.9's which used a different powerhead newly designed and built by Yamaha.

In your case the first thing I would check is to see if maybe your throttle cable is shot. Take the hood off and give it max throttle (not running). See if the butterfly on the carb is opening completely, if not may be a simple adjustment.

If the butterfly is fine then I would suspect a clog in the jet - at least that would be one of the next troubleshooting steps (of course assuming your compression and spark are ok)...."
 
"Graham, you know your stuff!

"Graham, you know your stuff! I am however a little ticked at the guy who sold it to me. He said he was the only owner and it was a 92 or 93 model. I have looked at the throttle cable and that looks fine. I did not check the butterfly to see if it opens all the way when throttled up while the engine is off. I will check that as soon i get off work today sir. Also, what is your opinion of this motor?"
 
I have one of these it is a gr

I have one of these it is a great little motor. One thing that you may not know is that the throtte will not open up all the way unless it is in gear.
 
"They were a well built, very

"They were a well built, very durable motor and it is new enough that it has the Thunderbolt 4 ignition on it - probably the best ever designed on a small outboard.

The one thing that I really dislike about this motor is the reed valve assembly - it is located around the crankshaft, so if you have an issue with the reeds you have to tear down the motor to get at it - that was one major point of change when they moved from the 9.8's to the 9.9's...."
 
"Gentlemen, I can't thank

"Gentlemen, I can't thank you enough for you help in finding where my problem was. By doing what you said, I found the the problem and it was so simple. I was looking down into the carb past the choke butterfly to the intenal butterfly, with it in drive and turning the throttle handle, the internal butterfly was not moving. I reached up to grab the plastic peice on top of the carb that turns the internal butterfly and it came off in mt hand. That cheap little plastic peice had broke in half and was just sitting there on top of the carb. No way it could open the internal butterfly, thus no air flow, thus no throttling up! After seeing this, I started the motor, (in a 55 gallon barrel full of water) and turned the butterfly by hand and the motor runs great! So ,I have ordered the part today and hopfully it will come in before this weekend so I can fish. Thanks so much for your help again! Here is a picture of the broken part and you will know exactly what I'm talking about!
149263.jpg
"
 
Back
Top