9.9 only runs with choke on

Joined
Feb 1, 2009
Messages
8
On my last fishing trip my '98 9.9 wouldn't run unless the choke was on. When I would cut the choke off the motor would run normally for whatever throttle setting I had it at for a few seconds and then die. This problem comes after a few years of the motor running fine up to 3/4 throttle and then losing a little power after rolling on full throttle. In the past I took the carb apart and cleaned it thoroughly and it didn't help the loss of power past 3/4 throttle problem. Could this be a fuel pump problem? Any suggestions would be greatly appreciated.
 
D

DJ

Guest
Re: 9.9 only runs with choke on

Your carburetor is in need of a disassembly and thorough cleaning.

Simple as that.
 

noelm

Senior Chief Petty Officer
Joined
Mar 8, 2005
Messages
761
Re: 9.9 only runs with choke on

when you pull the choke on, what you are in fact doing is decreasing the amount of air, and therefore increasing the amount of fuel so, as mentioned, you have a dirty/blocked carby, or quite a bad air leak in the manifld/gasket more than likely carby rebuild though, pretty simple thing if you are fairly handy and take your time.
 

druid_faith

Cadet
Joined
Jan 17, 2009
Messages
6
Re: 9.9 only runs with choke on

i agree to the percise cleaning but also check the gas mixture and or fule to air adjustment use hi pressure air to help clean jets in carb:)
 

woodducker

Seaman
Joined
Dec 11, 2007
Messages
69
Re: 9.9 only runs with choke on

Carb clean definitely and then link n sink. Also get a manual they truly help a bunch.
 
Joined
Feb 1, 2009
Messages
8
Re: 9.9 only runs with choke on

I have already disassebled and thoroughly cleaned the carb once when it was giving me the original loss of power problem and it didn't help. I will try it again though to try and solve the only running on choke problem. Thanks.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: 9.9 only runs with choke on

what year is it? you have a fuel restriction, either clogged jets, or totaly misadjusted. the reason for what year. it is not getting enough gas to run. thus the choke enrichens the fuel air mixture.
 
Joined
Feb 1, 2009
Messages
8
Re: 9.9 only runs with choke on

Cleaned the carb and it fixed the fuel starvation problem. It had sludge in the fuel bowl from mixing new gas and fuel system cleaner with really old gas and oil. It still didn't fix the poor performace at full throttle though. Any suggestions? Thanks.
 

sailfish252

Cadet
Joined
Feb 5, 2009
Messages
18
Re: 9.9 only runs with choke on

Remove the fuel pump and disassemble it. Check to see that the diaphrams have not been damaged, they are an orange color and it is pretty clear when they are damaged. GOOD LUCK
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: 9.9 only runs with choke on

Did you remove the high speed jet and clean it. it is deep behind the bowl drain plug, #23 in the diagram of the carb http://shop2.evinrude.com/ext/index.aspx?s1=bf6ad09c53cead335fcfd8a6471c0f7f

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

and clean the idle passage #17,also have you adjusted the slow speed needle #15,

slow speed adjustments:
Default Carb Needle Adjustments For Asorted Carb Variations by Joe Reeves
(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
 
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