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03-13-2011, 09:56 PM | #1 |
Not Yet Wild
Join Date: Mar 2011
Posts: 56
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1991 G9 engine running bad
I recently bought a 91 G9 golf cart. I am having trouble with it stumbling on full throttle. If I pull the choke and hold it out the cart runs fine but as soon as I let the knob go back in it will stumble on full throttle. I am wondering if the carb needs adjusted? I see a screw on the side but I am unsure which way to turn it. Also there is an adjustment screw on the opposite side of the carb it looks like it adjusts the throttle return. I have checked the air filter, spark plug and hoses for cracks. If anyone has any suggestions I would greatly appreciate it.
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03-13-2011, 11:23 PM | #2 |
G8 Specialist
Join Date: Jun 2009
Location: Phoenix
Posts: 7,799
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Re: 1991 G9 engine running bad
To start with, Welcome!
Now, you are experiencing an air leak in the intake system somewhere causing it to run lean. Quite often it is in the air filter housing. Take the filter canister out of the car, and assemble it on your work bench, making sure all the interior parts are in their proper little slots and that the top is sealed to the bottom section with the 4 rubber straps. There is also a large rubber O-ring in the filter housing top to help seal it to the bottom. The air filter housing is usually where the problem lies. Also,there is a plastic" intake manifold spacer", between the carb. and the head, that is common to crack and leak air,again, causing a lean condition. That spacer along with the 2 gaskets need to be replaced if when you check it, you find it cracked. It could also be a dirty carb, which would require cleaning it out. Best advice I could give you; Read this whole site on Yamaha's and do all maintenance that is mentioned here. You will come out with a great running car! Good luck Mike |
03-14-2011, 12:44 AM | #3 |
Yamahaulin' CC Rider
Join Date: Jul 2010
Location: Altadena, CA
Posts: 684
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Re: 1991 G9 engine running bad
The adjustment screw on the carb is a low RPM mixture adjustment, and has little or no affect on full-throttle operation. The other screw, as you correctly stated, is the idle speed adjustment.
Follow Mike's advice, and you should be good to go! Those air filter housings tend to warp, so check it really good! |
03-14-2011, 07:48 AM | #4 |
G8 Specialist
Join Date: Jun 2009
Location: Phoenix
Posts: 7,799
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Re: 1991 G9 engine running bad
Thanks Steve, I forgot to address that. Thanks for backing me up!! Turn that idle mixture screw in till it bottoms out, lightly, then turn out 1 and a half turns. Thats a good start. Fine tune it later.
And the throttle stop screw, I would just leave that alone again, for now. Find the air leak first. |
03-14-2011, 08:43 AM | #5 |
Not Yet Wild
Join Date: Feb 2011
Location: indiana
Posts: 61
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Re: 1991 G9 engine running bad
Check your spark plug.
My cart had the same condition and had the wrong spark plug installed. It wasn't long enough to get good spark to the combustion chamber. You need the NGK B5ES spark plug. It has about .75 inches of theads on plug. My cart had a really short Champion plug in it. |
03-14-2011, 09:53 AM | #6 |
Not Yet Wild
Join Date: Mar 2011
Posts: 56
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Re: 1991 G9 engine running bad
Thanks for the replies I will check the air filter box for leaks and the spark plug. I did'nt know the G9 engines relies on vacum. I'll let you know what I find. I have another question when you pull the choke knob should it stay out or go back in?
Thanks |
03-14-2011, 10:11 AM | #7 |
maintaining a low profile
Join Date: Oct 2009
Location: SW Virginia USA
Posts: 6,316
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Re: 1991 G9 engine running bad
Choke knob goes back in when released.
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03-14-2011, 12:28 PM | #8 |
Not Yet Wild
Join Date: Mar 2011
Posts: 56
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Re: 1991 G9 engine running bad
I checked and my cart had an autolite 404 spark plug in it. It kind of smells like gas. I ordered an NGK B5ES plug hopefully that should help. I also checked the air filter box and the inside gasket that seats the top of the box is old and torn and the hooks on the side that hold the top of the box to the bottom are gone they just had wire ties holding it down.
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03-14-2011, 05:08 PM | #9 |
G8 Specialist
Join Date: Jun 2009
Location: Phoenix
Posts: 7,799
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Re: 1991 G9 engine running bad
Both are kinda important. Are the hooks where the rubber straps attach still there?
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03-14-2011, 09:40 PM | #10 |
Not Yet Wild
Join Date: Mar 2011
Posts: 56
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Re: 1991 G9 engine running bad
three of the four plastic hooks are there. also the rubber hold downs are gone. should I order a new top air box cover? or will I be ok with three hooks?
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