I have a U42T Minicab dump with the 3g83 - Mikuni carb. The engine starts fine and idles up with the automatic choke - no issues. Once warmed up, it will not idle below 2300 rpm. Turning the idle down will cause the engine to start rolling the (rpms up/down) until it eventually stalls. Running the truck down the road - truck runs great until the first stop sign - then stalls. Points to note: Carb is a new factory rebuilt from Yokohama - The old card had the same result/behavior as the new carb. Engine is a new rebuild from G&R New Cap/Rotor and points module. Played with the timing as much as possible at 2300 rpm Played with fuel air mixture screw - no luck Fuel pump is an aftermarket 2 wire - pumps fuel as expected Vacuum lines - no leaks - but I do not have confidence that they are connected to the correct ports. The vacuum advance is correct based on the Russian diagram (https://mitsubishi.epc-data.com/minicab/u42t/hfdv9/intake-exhaust/emission-control/) So any takers on this? Here is a couple of Videos: COLD START WARMED-UP Thanks! Jim
Has anyone solved this? My 1990 s83p Hijet is having the same problem. Any help is appreciated, thank you in advance.
I haven't been able to figure this out - its kicking my ass. My staff are using it for hauling manure and I just have the idle screw cranked to keep t running. It has to be a vacuum issue - I really don't know. The old engine drank a quart of oil per week but at least idled. I have the Suzi in my garage now doing some front end work. Once I get that up again I will pull the Mitsi back in and try to work it out.
GR Imports Has a page on common problems blamed on the carb, and pictures of most of the carbs, so you can at least know what is supposed to do what. https://docs.wixstatic.com/ugd/d494d1_91ad485ec9aa4f7ab3e94d24a1e61870.pdf
Update: Problem Solved - Finally figured out WTF was wrong - human error. In my original post I mentioned to rebuilt engine. The wiring harness had been hacked into by the previous owner - when we hooked everything up there was no power going to the switched hot (positive) on the alternator. I ran jumper an the alternator worked. After months and giving up on the idle issue I decided to track down the issue with the alternator. Pulled the wiring harness going to the carb/alternator and found a melted wire. Fixed and re-taped close to what it looked like from the factory. On reinstall the plug that had been going to the alternator now lined up with the carb and vise versa. Come to find out the whole time I had the two plugs reversed (they are the same style plug) - plug for the carb was in the alternator and the plug for alternator was in the carb. Interestingly enough the wire colors going to the alternator match the wire colors on the carb solenoid. Can definately see how the mistake was made. Truck runs great - idles - charges - the works. Hope this post save someone else from the same mistake and a few less grey hairs.
The plug that goes to the alternator has two hot (positive) wires. One is 12 volt, the other is a lower voltage (don't recall the voltage but it was definitely less than 12). The plug going to the carb has positive and a negative wire (12 volt).
Congrats!!! Been following this thread, since Oct., Pretty amazing, that those wires were able to even make it run. Naturally we don't know what the previous owner used as a reference to re connect the wiring, and vac. lines. To me a lot goes back to not being able to get good working schematics to follow for these neat little units that were built oversees! Sure do wish I had a Chilton's, or Motor's manual on these things like we had growing up!
