Only runs on full choke and up to 1/4 throttle

[medicsnoke]

I have a Evinrude 9.9 HP, year prob between 1987-1992. The motor has worked fine ever since Ive had it. It sat pretty much all last year and over winter with no winterizing. Anyhow, after pulling it out this year it wouldnt run. After some seafoam and carborator cleaning it now runs. However the MOTOR ONLY RUNS ON FULL CHOKE. If you push the CHOKE in when running, the motor imeadiatly dies out.
Then when on the lake, and the motor has a load against it, the motor will only run to about 1/4 throttle and then just dies out. As long as you run the motor under 1/4 throttle, it seems to run just fine (fine other than being on full choke).
Anyone have any suggestions on what maybe wrong or what I can try next?

 

[CATransplant]

Re: Only runs on full choke and up to 1/4 throttle

It's almost certainly a dirty main jet orifice. If you're using stale fuel mix, that will make it worse. See this link:

http://forums.iboats.com/showthread.php?t=244013

 

[medicsnoke]

Re: Only runs on full choke and up to 1/4 throttle

I will take the carb apart for the 3rd time 2marow and take it to the motor cycle shop and have it cleaned proffesionally. Thanks you for the qucik responce. Any other guesses or is a dirty carb/jet the consensus?

 

[fakeplay]

Re: Only runs on full choke and up to 1/4 throttle

replace both needl valves. Thas what I did and it ran like it was suppose to.

 

[Rick.]

Re: Only runs on full choke and up to 1/4 throttle

With all due respect I would not change the needle valve unless it shows sign of damage and/or wear. I agree it sounds like the carb. needs cleaning. With the choke on your starving the carb. of air and thus making the fuel/air mix much richer. Running it with the choke on says your not getting enough gas to run in the normal position. After it is cleaned go to the top of this forum and look in the Top Secret Stuff post and you will see how to set your needles. You could also have a week fuel pump or your tank vent closed but I wouldn't start there. Best of luck to you. Great motor you have there. If you need more advice by all means ask but your specific year would be helpful. Rick.

 

[medicsnoke]

Re: Only runs on full choke and up to 1/4 throttle

Still having this same problem after a very good carb cleaning and new gas. She runs wide open now, but still will not idle unless at 3/4 choke. I have a carb rebuild kit but am hesitant to put it on cause very thing looks in good shape. More info on checking all of these possible problems would be appreciated:

How to check the needle valves
How to check for a week fuel pump
Tank vent? This just totally confuses me

By the way, according to the mod# it should be a 1988, and the carb in this motor has the fuel well inside the float bowel, I saw one carb model that doesnt have a fuel well. Any suggestions would be appreciated.

 

[kenmyfam]

Re: Only runs on full choke and up to 1/4 throttle

Re-Do the carb. Something amiss with fuel delivery !!!!

 

[Rick.]

Re: Only runs on full choke and up to 1/4 throttle

Not sure why you would get a carb. kit then not want to use it. I didn't think anyone was as tight as I am!! Just kidding. You should put it in and be done with it. You haven't any idea when the carb. was done last do you? You could open you slow speed needle valve (1/4 turn, counter clockwise, at a time until she idles with out the choke) and if that doesn't work I think the carb. is not as clean as you think. You can inspect the Slow speed needle visually. There should be no ridges or cuts in it. Week fuel pump can be checked by pumping your bulb when the motor is about to die. If motor RPM's come back the fuel delivery is a problem but that doesn't necessarily mean you pump is weak. The tank must have an opening to atmospheric pressure. The plastic tanks have a little screw vent in the middle of the fuel cap. It must be opened. The OMC steel tanks have a couple of pins in the tank to hose connection that once pushed in, the tank is vented. If your in doubt, remove the gas cap and see if that makes a difference. Best of luck. Rick.

 

[HVSTRINE]

Re: Only runs on full choke and up to 1/4 throttle

It sounds like the carb is still dirty to me. I had the same problem and just ran it choked partially until it passed whatever was blocking the fuel flow.

 

[medicsnoke]

Re: Only runs on full choke and up to 1/4 throttle

Used the carb kit and found that my carb was missing the low speed pick up tube. That must have been all the pieces of junk I found in my dirty carb origanally. Anyhow, almost missed that pice when re-building the carb, but once we (guys at the firehouse) found that.................motors running like a champ. Thanks for all the help guys.

 

[kenmyfam]

Re: Only runs on full choke and up to 1/4 throttle

Glad all is now well.