I have a new to me 97 minitruck with the 3G83 motor. I've searched around the forums for the last couple weeks and found lots of things to try, but none that have been successful. When I got it there was a bad idle and lots of smoke. I have it idling well now and at <1/2 throttle it runs great and revs well but if you go to full throttle it stumbles and eventually dies. As you rev, there is lots of white smoke as well(no smell of coolant and radiator remains full). Things i've done New air filter Pulled/cleaned carb New fuel Checked compression (~130 on each cylinder) Set timing Checked plugs (black, seems rich) Set idle New oil-- previously oil smelled like there was fuel in it. My thought was the thinned oil was leaking past the rings but with compression and new oil it still smokes Removed fuel return line, routed into an empty gas can None of the above changes fixed the stumbling problem. It runs much better at idle but falls down at high revs if more than 1/2 peddle is applied. I believe its flooding but most of my motor experience is on bikes with simpler carbs/fuel systems so very well be missing something. Any input is appreciated
I know you said that you are not losing coolant, but usually white smoke does indicate a bad head gasket allowing coolant into the combustion chamber. - - Hope you find it.
I would generally think the same but its not dropping at all and there is no "sweet" smell to the exhaust, it smells like fuel not anti-freeze
Sounds to me you have a wrong mixture, in this case too little air. The MAS screw is on the front left(that is, if you think front is where the cab is pointing, and left is where the left side is on the cab) side of the carburetor, which at least on a U15T with a 3G81 is accessed by lifting up the drivers seat(from this vantage point it is to the right, near the front). Don-in-Japan's pictures of the fuel system in a 3G83 leave it a little of a mystery how the MAS screw looks https://minitrucktalk.com/threads/carb-tuning-techniques.3682/ post #16, but Dan's copy of the 3G81's service manual showcases it quite well http://www.box.net/shared/0kpymfg7bs
