Yamaha G9 Not Running Properly

[Ahale22h]

I had a previous thread but I didn't get the answer so I'm re-posting in hopes someone will have a new idea for me.

I have a 1995 G9 Yamaha gas golf cart. It ran great and the next day it would barely run. I cleaned the old carb and put it back on with no change. I ordered a new carb and put it on (no change). I replaced every gas line and installed a new fuel pump. I also changed the fuel filter. I drained the gas and added new gas. After none of this worked, I made a gravity fed tank (temporarily just to see the result) and attempted to run the cart with it, still no change. I checked the plug and it was a little wet and oily, I ordered a NGK plug and it didn't change anything either. I also checked the valve lash.

I haven't replaced the pulse line because I can't see the end that goes into the motor but I have a little bit of a pulse when I put my finger on it. It visually looks like it is in good shape. I also checked for air leeks (gas bottle method) and there were none detected. I replaced the coil and the plug cap... still no change. There seems to be enough fuel pumping. It runs a for a short period if I fully choked it.

I used a timing light and it seems to indicate a skip about every 3 seconds. (Light is flashing very fast.... then a quick/brief skip).

My compression is 160.

What am I missing?

[slonomo]

I just think you haven't bought enough parts yet

Only kidding. I'm not sure if I can solve you issue or not, but when I can't get an engine running I always go back to the basics.

1. Fuel - put the fuel line into a empty clear water bottle and crank for 30 seconds, you should get a few ounces of fuel in that time. Also verify that the fuel is getting into the fuel bowl.

2. Spark - I usually check spark with a HEI type spark tester, doing the "lay the plug on the head" method is not always that accurate.

3. Air - there should be a clear path from the intake to the carb, with a new clean air filter

4. Compression - I typically squirt a small amount of oil in the cylinder and do a "wet" test. I'll usually cycle the engine without the spark plug for 60 seconds then do the compression test.

The rule of thumb, if you have fuel, air, compression, and spark....it should run.

To eliminate the carb: I never use Ether or starting fluid to get a gas engine running, I use a spray bottle with clean fresh fuel and spray it directly into the intake with the carb removed. It should start easily this way. If not, you have another issue. If it does start with the spray bottle gas, then your carb is not working properly.

Another thing to check is your oil level. If the oil is too full, it can coat the spark plug with oil and it will foul. I have had plugs that will fire in open air, but not in the wet oil soaked cylinder. I will often leave the plug out and cycle the engine with the fuel line off, this will help clean out the cylinder. If there is a ton of oil in there, spray some carb cleaner into the intake when you cycle the engine, it will help purge some of that oil. Once a plug gets oil soaked it should be replaced.

[slonomo]

Well I just read through your other thread, lots of good info there. Not sure why you thought you weren't getting the answers you needed.

Fuel is easy to figure out and test. Just take the carb off and see if you can get it to run with the spray bottle method. I don't like using Ether because it can blow the head right off the engine (seen it done), it's highly volotile.

The compression test "should" be accurate.

The spark test is still suspect. As someone else stated in the other thread, if you test it with the plug on the head/valve cover bolt, make sure you have a good contact to the threaded body of the plug to the metal. The spark should be bright white/blue color.

[Ahale22h]

Thanks, I'm about to leave for work so I'll go through this tomorrow when I get up. I wasn't saying the information wasn't good... I was just saying that I haven't found the problem and the comments had stopped.

I'll go through step by step tomorrow. I have tested with a spark tester and by pulling the plug and arcing to a bolt. The spark appears to be good until I use a test light.

[Tyler_Veasey]

According to the last post in the previous thread you tested resistance across your coil and it was out of spec, then you have discovered a problem. Maybe not the only problem but at least thing that can be eliminated.
Also, make sure the new carb you put on was adjusted properly. This means position of the air mixture screw as well as ensuring that the jet sizes are correct.

[Ahale22h]

Hey guys.... I put the fuel line into a empty clear water bottle and cranked for 30 seconds, and got a couple of ounces of fuel. I took the carb off and there was some fuel in the bowl. I sprayed fuel directly into the intake and it seemed to run good with every squirt. I put the carb back on and it ran decent (not great). I was adjusting the carb and just couldn't get it smooth. While trying to adjust the carb it quit running again. I retested my spark and got nothing. I rechecked my gap and my plug looked good (it was barely wet). I tried another plug and still no spark. I have already replaced the coil so I will assume I need to test the other electrical components (which is my weak spot lol). I also rechecked the compression both wet and after running the cylinder dry for 30 seconds. It was at 157.

[Tyler_Veasey]

Back in the days of points ignitions, this would be a sign of a bad condenser. I'm not as well-versed in electronic ignitions so I can't say for sure what is failing in the ignition on your cart but it sounds more and more like an ignition problem.

[CP241]

I think I told you it sounds like a spark problem.

There’s not much to test. Check resistance between the white/red and white/black wires at the pickup coil. Check resistance of the primary and secondary coils in the ignition coil, and the plug cap.

My guess is still a bad ignitor. Sorry I didn’t give you whatever answer you were looking for, I don’t know what you were looking for. But there’s no way to test the ignitor other than swapping it with a good one, and a good one is around $400. Stay away from the aftermarket nivel ones. They suck. Trust me from personal experience

[slonomo]

Originally Posted by CP241

I think I told you it sounds like a spark problem.

My guess is still a bad ignitor. Sorry I didn’t give you whatever answer you were looking for, I don’t know what you were looking for. But there’s no way to test the ignitor other than swapping it with a good one, and a good one is around $400. Stay away from the aftermarket nivel ones. They suck. Trust me from personal experience

Those factory ignition parts are hard to come by unless they are still available from the Yamaha dealer. When parts are discontinued, there are people that seem to hoard these parts, that might be your best bet.

I looked up the ignitor

https://shopyamaha.com/parts-catalog...f-24529ea97178

It appears to be available NOS if you can find one.
part # JG5-82305-00-00 according to the page I posted above.

When I googled it I found this:

https://www.partspak.com/productcart...00-p238696.htm

https://www.partzilla.com/product/ya...G5-82305-01-00

https://www.vintagegolfcartparts.com/Item/YA_IgnitorG9

Good luck.

[CP241]

The only other option is HEI conversion. While maybe not ideal because timing is fixed instead of variable advance, it is cheap. I never had any problems with mine.