Help with Rough Running (New to Me) G2

[mineralgray610]

Hello,

My friend bought a Yamaha G2 last month. I have now inherited the cart project as he is not mechanically inclined. The cart does not have serial#. It was used as a golf cart and appears to be in very good condition. It does have quite a few rounds on it. The cart ran pretty good the night we purchased it.

After he purchased it, he installed the zip tie on the governor trick.

Shortly after this, the cart began to run sporadically good and bad. It would run great for a few holes of golf and then backfire, pop, and run overall doggy. It appeared that the cart was not getting any fuel. We then removed the fuel pump and it was full of what appears to be the glue from the factory fuel filter(see attached pic). We then bought a rebuild kit and replaced he fuel filter with OEM parts. he fuel lines were free of obstructions.

The rebuilt fuel pump and filter did not appear to help the cart. Finally, it would not move(barely run). We then took the cart apart and determined that 3 of 4 starter/generator brushes were bad. It was also apparent that the float was stuck as the air box was half full of gas and the crank case was full of gas. I had my dad (retired mechanic) pull the carb to confirm, but the factory carb fell into pieces as we took it off.

We could not find an OEM carb and purchased a knock off from Golf Cart King. We also replaced the starter belt and drive belt. There is no change to how this cart runs.


Rebuild Diaphram Pump
New fuel filter
New Stater Generator and belt
New drive belt
New Carb


We a have adjusted he carb to factory settings and went from there. We have new bands on the air box. We even tried to run the cart without the airbox and there was no change. It acts like it is running rich. The cart always runs bad when cold and will get a little better with the choke open. Once warm, the choke makes it run worse and it rarely runs good (5 out of 18 holes).


I have not checked the timing, compression, or valve lash. Where do I go from here? Ignitor? Valves? Sorry so long. Thanks in advance.

[slonomo]

Did you flush the fuel tank? Replace with new clean fuel?

That stuff you think is glue is not glue. It's classic fuel gunk. The tank is probably loaded with it.

[mineralgray610]

We did drain and clean the tank. It no longer has a contaminated fuel issue. Thanks though.

[slonomo]

If it runs better with the choke on when cold, then it's working correctly. When warmed up, it should run worse with the choke on. Sounds like that is normal.

You said it seems like it's running rich? Is there black smoke coming out of the exhaust? That's how you know it's rich. Also take a plug reading. If it's black soot covered then it's running rich.

[slonomo]

I would definitely check and adjust the valves next. While you're at it you could check the compression since that's a quick and easy thing.

[mineralgray610]

We finally found the issue. I want to share the story should someone have a similar problem. Yesterday, I put a new plug (for G9) in the cart. I also used a autozone cylinder compression tool. It read 60psi. I thought we needed new rings. I then found a old thread discussing a bad gauge from autozone that read 60 for another member. We then moved the cart to my dad’s shop and used a Mac Tools gauge. The cylinder pressure showed 120. We then looked at the valves. The exhaust was .007 cold and the other was tight. We adjusted the valves to .004 and had to make a gasket fit the Valve cover. We then took the jets from tho old carb and put them in the new carb and adjusted it to factory specs for ps and idle. Next, we had to rethread the plug. It wasn’t going into the head far enough. After we adjusted the valves, we had 150 cylinder pressure. The cart runs pretty good now. Thanks all for your input.

Note: I found two threads where a rented pressure gauge read low. Make sure you get a good gauge.

[slonomo]

I've actually have that happen with two store bought compression gauges. So, the spark plug wasn't sealing was the problem? Or the jetting? Or both?

[mineralgray610]

Originally Posted by slonomo

I've actually have that happen with two store bought compression gauges. So, the spark plug wasn't sealing was the problem? Or the jetting? Or both?

The gauge must not have had a good seal. Crazy low reading. It read 150 with a better gauge and same jetting.