G9 With poor running engine

[leiwal]

I am a relatively new member, this is my first post. My G9 which I have had for a couple of months is/has had problems runnning. Once going it runs fine, but sometimes when starting the engine it just flounders around never getting enough rpms to move the cart. It will backfire a little as it flounders, keeping the accelerator depressed a little will keep it running for a lomg time but nothing useful. Sometimes it will recover from this floundering and clears right up and runs fine. It seems that it may be running rich, and seems that choking to much may get it in this state. I did adjust the air mixture screw by seating it, and then cranked it out by a turn and three quarters. This may have helped a little but today I couldn't start it (air temperature 25 degrees). It has been more of a problem in the colder weather (25 - 32 degrees) but has also been a problem in warmer weather. I've checked out the air filter and air box, all seems to be ok. I'm looking for suggestions on what the problem may be. Thansk in advance for and and all help!

Leigh

[Mike Mac]

How old is the gas? Put in fresh gas and fuel filter. Clean and or replace air filters. Make SURE air filter housing is reassembled correctly, no air leaks. Replace or regap spark plug,.030. If it runs, get it warm, then turn idle mixture screw very slowly while running, one way or the other until the motor is happy and runs the best.
Then start looking at clutches, look for zirk fittings, start with 1 pump in each zirk. Then I put a very fine film of WD40 or something where the ramp shoes contact the ramps on the secondary clutch sheave.
Read all posts on Yamaha on this site, you will read a wealth of information about your car. That what I do and I thank all you guys for taking the time to post all your remedies!!

[HDPwolf]

I agree with Mike all good starting points, but take a close look at that air box make sure its sealed good, mine did same thing and had bad seal on lid

[DOOmsman]

I would guess fouled idle jets in the carb. It gets worse when cold hints to it being lean.
Is the carb clean?

[sho305]

I think stock is 1 1/4 turn out for idle jet, I would set it 1/4-1/2 more in winter but realize it only works when the throttle is about less than 10%. They start best feathering the throttle from turning over idle to about 1/4 throttle. If your throttle cable is set to pull the throttle on before the starter runs it can start harder. Backfire is sign of leaky airbox, fouled plug, dirty carb. I'd try those first like said, it is very important on these yami carts. Cart will perform better with clean lubed clutches and belt wider than 1", wider yet for lifted carts...but often does not affect starting unless the belt drags causing the cart to move on the starter.

Having the idle jet too rich can foul the plug in hot weather, it does on mine though mine is modded, but I don't have to choke until it is under 60F for a cold start. It must be around 1.5 turn out not sure, and my main jet is hogged out as is parts of the airbox that made it necessary. Any mods to the box require rejetting.

Lastly the plastic spacer carb to head can crack or leak. If you can get it to idle you can spray wd40 or carb clean to see if that changes idle speed/etc to find leak. You should be able to secure the cart, press the pedal just enough to start it, set the idle jet and idle speed so it just barely idles very slowly. It must run/idle without the throttle being pulled open by cable, when the pedal is moved just enough to make it start. That is way I find they start and work best. The idle should be just faster than the starter spins it, this ensures nobody drives it really slow on the starter and kills the battery/wears out the starter/etc. But it should not make the cart take off, though some creep depending on how the belt is set.

[leiwal]

I appreciate all the very helpful tips on correcting this problem. As soon as it warms up some I will dive into resolving the problem(s). I have two moe questions. First, should the yami carts idle with no pressure on the pedal? I remember reading on this forum that it should not idle but stop when no pressure on the pedal. This seems a bit odd as every time you change direction the engine stops. Maybe the idea is that the gas carts behave similar to the electric carts. Secondly, I have a service manual for the G2 and G9, it gives good detail for the G2 gas engine but doesn't specifically say anyting about the G9 engine. Is the same engine used in both the G2 and G9?

[sabercat]

g2 and g9 engines are nearly identical. the g2 has an electrical rpm limiter, were the g9 doesn't. yamahas also don't idle and don't run without pedel presure, there is a mircoswitch under the petal that kills the ignition when released.

[sho305]

G9 has less compression, iirc displacement is slightly different but I'd have to look it up. There is not much difference overall.

All golf carts only run/move with the pedal down. Should push the pedal a little and it clicks, engine rotates, engine idles....push the pedal over around 1" movement at end of pedal and engine begins to throttle up and cart moves away. If you hold pedal just on it will sit and idle. The engine needs to stop to shift gears, the trans only has dog gears and can not be moving. This is a problem with big block carts as the belt drags and starts spinning the secondary and trans shaft when you shift to neutral and by the time you get to the other gear it grinds. Actually a brake on the secondary clutch would resolve it if applied in neutral.

You can rewire the cart to run when the key is on, but the system works so nice once you use it few do.