It was the Spark Plug...

technomayor

I drove my 2011 Yamaha Drive G29 Gas Cart around to the front of the house loaded with ladders and christmas lights to decorate the house. It acted like it was running out of gas and died. I checked the fuel level, it was a little low so I added some, it would fire a little, but still wouldn't start.

I pushed it back to the shop for additional troubleshooting. Sprayed a little starter fluid in the carb and it fired up and ran for a few seconds. So I thought it must be fuel related and started troubleshooting the fuel system. Disconnected the fuel line from the carb and cranked the engine, fuel pumped out of the hose, so fuel pump, fuel level, fuel lines are OK. Opened the drain on the carb bowl and fuel drained out, so we thought it must be some kind of gunk in the carb.

We removed the carb, disassembled it and thoroughly cleaned it. It was very clean and we didn't find any dirt, blockage, etc... We reinstalled the carb and tried to start it again. One backfire from the carb and then nothing.

We pulled the spark plug and it was wet with fuel. We cleaned, re-gapped, and reinstalled the plug and it still won't start.

We're now thinking it's a loose connection somewhere in the electrical/ignition system causing an intermittent loss of spark. So out comes the schematic and multi-meter for some electrical troubleshooting. We find nothing and decide to go buy a new spark plug before we dig any deeper.

Connected the new spark plug and laid it against the cylinder so we could see any spark. Cranked the engine and saw a consistent spark. We then swapped the old spark plug and saw no spark. Our first aha moment. Installed the new plug and it started and ran as good as new.

So... after a 1/2 day of troubleshooting it was a $4 spark plug!

The old plug had no visible issues, so we think there may have been an internal crack/short that finally broke for good.

BGW

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smokindawg

Spark plugs can be a pain for sure. More work than you needed to do but the main thing is your back running.

SandbaggerYDRA

But the important question is, did you get the house decorated?

technomayor

Yep, gotta keep the wife happy. Got the house done and will be parking the 86 year old lawn decoration in the front yard on the weekends.

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classycarts

Let me guess............. was it a Champion sparkplug?

technomayor

No, an original NGK.

classycarts

WOW, never had a problem like that with a NGK.

Cvans

Something else that can make checking plugs a headache. Sometimes you can check the plug the way you did and it will have a nice arc but will not fire under compression. Back in the late 60's when I worked for Toyota we had a spark plug tester that would check the plugs under compression with a viewing window. You'd be surprised how many times we'd find a plug that would fire just fine until you added air pressure.
As far as spark plugs are concerned, when in doubt, throw it out. They don't cost that much.