[jpatters]

I’ve got a 2000 Quadmaster 500 that won’t start. I’ve had it to a shop and they couldn’t figure out what was wrong with it. So now I’ve got it all torn apart since I’ve got nothing to lose. I’m just going to list some facts about it and see if anyone can help me put the puzzle pieces together.

• The battery is fine
• All the fuses are good, including the main fuse
• The neutral light and reverse light do not come on
• The neutral switch seems to be in working order
• The headlights work in ignition position two
• The ignition is making the proper connections in both positions
• I’ve tried two different CDI’s in it. The shop concluded that was the issue so I bought a used one from a reputable dealer that was said to have come out of a quad that was running fine
• The regulator/rectifier checks out
• The voltage across the neutral bulb changes from 0v to 0.7v when placed in neutral (I assume this should be about 12v)
• The same is true for the reverse and coolant light
• The voltage across the neutral relay is 0.7v (I assume this should be 12v)
• The neutral diode is good

I think that’s everything. If anyone has any ideas I would love to hear from you. I’m racking my brain. I’m to the point where I’m just measuring resistance in the wiring harness to see if there is a loose connection somewhere.
It was working fine until one day it just stopped mid run and that was it.
Thanks in advance!

 

[CFM]

I can help you with troubleshooting. The first step is always checking spark, fuel, and compression. All 3 are needed, in the right proportion, for the engine to run.

It needs 90lbs or more of compression to start. (some things have a compression release which can bend the rules a little) It's best to find out the spec and go by that, or if you have access to a leakdown tester, that's a far better test.

Spark, you can get an idea by laying a spark plug on the head and checking it that way, but there are situations where you can have spark at the plug, but not under compression. For that reason, I like using a tester with an adjustable gap. It should clear a 3/8" gap. If it won't, it's probably not adequate.

Fuel, this one is more difficult to test, which is why I do it last. after I know I have spark and compression. You can take a sample to make sure there's no water, make sure the fuel is fresh enough to run, if it's debatable, change it. The carburetor can still mess this up, so a quick test is to spray some carb cleaner or something down the throttle body, and see if it starts igniting that. If it does, but won't run, the carb is probably plugged up, which is very common now days, with our craptastic fuel.

 

[jpatters]

Thanks for the offer. I actually got it figured out yesterday morning after troubleshooting for almost a week. I would have had no way to test spark, fuel, or compression though. There wasn’t enough voltage making it around the quad for it to light a bulb or even attempt to turn over.
It turned out to be a short in the wiring harness in one of the wires leading to the ignition. Replaced a section of the wire and it works as good as new.