1992 Yamaha Gas G9 Wont Start

[sho305]

Originally Posted by baronske

Next project, putting a John Deere L110 vertical shaft engine on an electric golf cart.. woot!

Sweet, please post it up in the big block section!

[baronske]

Ok, I am at a loss. I got the new carb in the mail yesterday, did the switch. It still turns over but won't start.

Summary; spark is good, compression good, fuel pump working, carb is new. I replaced the hold-down straps on air cleaner box. Hoses are all tight.

Any other ideas?

[sho305]

Change the plug and try it again, they can be strange about the plug fouling it will still spark outside the engine. Another trick for that is pull the plug boot part way off so there is a little gap above for the spark to jump, sometimes they fire right up that makes the spark stronger. It should start with no air hose on the carb, it may not run well but should start. Check and see if you have air coming out the exhaust, I heard of those plugging the muffler but not very common. Or a few bolts and you can pull it loose from the head only takes a minute, see if it runs then.

[bigstik40]

Like SHO suggested, time to check compression. Could be stuck valve or have seen quite a few times on the forum where pushrod comes off rocker arm.

[baronske]

Ok, I didn't get to read the last post from Sho305 before I did this:

I will be the one to tell you all, spend the $3.00 before digging deeper into your diagnostics. The spark plug test was fine, I had good spark. So, as a last ditch effort before taking it in to a small engine mechanic, I bought a new spark plug, and...as you might guess.. IT STARTS and runs GREAT!

Thanks for all the help on here and to all new readers, spend the $3.00 first.

[Mike Mac]

Good deal, glad you got it running!

[bigstik40]

Great that you got it going!! Good information for the data bank also. Always good to see what works for problems. - RAY

[baronske]

Ok, I am back. Golf cart ran great for a day. I noticed on the new carb, on the bottom, there is some sort of drain that was leaking gas. I tightened that screw down. My daughter drove it this morning and now it is running real sluggish, won't get up to speed.

Thanks!

[baronske]

Update:

I noticed a 1.5" long crack on the air box below the lid. I assume this might be my problem. I have looked on many websites and can't find a new one.

Would this cause the sluggishness and if so, where can I get one?

[sho305]

Any leak in the air box causes lean running, the carb is jetted for it. I would guess you need a used one, people that put big blocks in often get rid of them. Or you can rejet the carb, or put a larger air filter on and rejet for that. The clone I put in I used a car air box the filters are $7 also piped it to the front of cart so it never gets dirty.

My stock G9 I took the silencer thing off above the generator, that seemed to be the major restriction in there. Other mods inside didn't seem to do much, but I had to hog the jet a fair amount for the silencer. I used a torch tip cleaner to file the jet out. Took the carb out and removed the jet and put it back in not real tight. I could take the bowl off and jet out in the cart and file it then, did that about 6-8 times to get it right while driving it around. It would only idle when I started, as you can adjust the idle mix but it has no effect after about 1/8 throttle at carb.