Help needed: 1994 4X4 that I bought not running. It wouldn't roll because rear diff would hang up, and I could see lots of parts had been thrown at it. Rebuilt the diff, new brakes, and put a starter on it to get it running. It came with factory carb and amazon carb. It has had a stator, coil, and carb from PO. I bought another carb because it would start right up and idle with both of the others and I thought a new one would help. You can see in the video it is doing the same thing. Breaks up when giving it the gas. Choke doesn't help, though it seems lean. It ran pretty good for about 10 minutes when I put the fresh carb on but still would do WOT. Thoughts?

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Try another new plug, new doesn't always mean good. I had a 300 that would cut out when you gave it throttle, just above idle. If you gave it throttle really gently though, it would rev up. Had to be carb, but no, fitted a spare carb and it was exactly the same. Fitted a new CDI and it was an instant cure. If it is CDI be warned, four different CDIs were used on 300s and all but the last look exactly the same, except genuine ones have colour coded plugs and sockets, but they are incompatible. Another possibility is blocked exhaust or worn camshaft.

 

Also check air snorkle for dirtdopper nest or rat nest try to remove air box lid the see if will rev up[that gives more air] if still runs same than air way ok..does sound like cheap spark plug try to replace lie said above get NGK DPR8EA9 if you can

 

Little update. I grabbed a new NGK and it turns out I had already put one in it. It has been sitting for a couple months because I gave up on it after the I rebuilt the diff. Anyway, the the "new" plug in it and the other new one I just bought are getting black with soot. That confirms it is not a lean condition even though I am getting some backfire from the carb. I will pull the rocker cover this evening an confirm the cam chain and timing.

 

I want to give everyone an update. It seems to be fixed...ish? I noticed that the PO had not bolted on the coil, it was just laying under the front plastic. Our coils have a ground wire at the mounting point. That got me looking at all the electronics. It has a new regulator. Sure enough the red and green wire from the regulator wasn't hooked up. After connecting the coil and regulator I charged the battery over night and it is running great!