Hello All, I have searched for a post of someone with a similar issue, and those that did ended up not being my issue... Basically, anything over half throttle, the carburetor acts like it floods out. With the airbox removed, it actually spits fuel spray backwards and the motor dies. It doesn't matter if it's in gear, out of gear, etc. It always does it. I have a 1992 Carry DD51T KKUG-SB2 that is 100% all stock (except for aftermarket carburetor). When I purchased it, there was no airbox on it and the choke circuit was disabled. Come to find out, the choke was disabled because the coolant lines feeding the choke release were completely clogged. I'm guessing the previous owner didn't realize that and was just OK with putting his hand over the carb to start the engine . After I got the choke thing figured out (it works perfectly now), I started tackling this over half throttle performance issue. No matter what I did, I couldn't get it to go away, or even change. I immediately suspected the carburetor, so I purchased a new aftermarket one. Zero change in how it performs. So now I suspect I have 2 perfectly good carburetors. I ensured the vacuum lines were all connected, or properly plugged off, but no change. I thought maybe it's a calibration issue with the carburetor but, I find it hard to believe that if it were the carburetor jetting or settings, that 2 would perform identically - but I've been wrong before... I went after the ignition timing next, and it was pretty close to 15 degrees BTDC. I tried changing it, but it made no difference, so I don't suspect that as being my issue. With my timing light hooked up, the timing seems to advance on vacuum as it should. I did put new spark plugs in it. I haven't changed the cap, rotor or wires yet, but they are all in excellent shape - not saying they aren't the problem though. When the engine cuts out over half throttle, my timing light continues operating OK. Since this engine is so quiet when running, I then started to suspect the exhaust possibly being clogged (catalyst maybe?). I pulled the exhaust off the head pipe / catalyst assembly, hoping to see plugged catalyst honeycomb material. To my dismay, the catalyst material has already been broken up and removed... . I ran the truck without the exhaust hooked up anyway, and no change whatsoever to the over half throttle performance. So, carb, ignition and exhaust seem to not be the problem. So now, I'm leaning towards the cam timing being a cog or 2 off, possibly? The engine starts and runs flawless. Not a miss at all. Not ever owning a vehicle with this small of an engine before, I don't have any expectations on torque or HP, but it seems OK. I can start out in 2nd gear just fine and accelerate up to 65 ~ 70 kph just fine - as long as I don't go past half throttle. Down slight grades, I can get it up to 80 fairly easily. I don't have a tachometer hooked up, but at 80 in 4th gear, it's revving pretty high. I haven't pulled the timing cover off to check it yet. I just wanted to get some thoughts from folks who have a lot more experience with these engines than me before I do. I have a water pump/timing belt/tensioner kit on the way for it, so I will be changing it as preventative maintenance as it has 75,000+ km on it. Anyway, sorry for the long post. Any and all thoughts or ideas are greatly appreciated. We really dig this little truck and it's going to get a lot of use in our family - even if it stays just the way it is (it runs that good up to half throttle). But I'd just like to get it running perfect, if at all possible. Sincerely, Robert
Your timing should be 7 deg BTDC stock or even maybe advanced to 8 or 9. I would start with getting the timing back to where it belongs which may involve redoing the timing belt. Get a new one if you are going there. There are kits that include the belt, the idler pulley and maybe a water pump. Its worth doing them all if you are in there. Get the timing right and then redo the carb adjustments for idle air mixture and idle speed. Oh and keep an airbox on it, that greatly affects the carb tuning.
Thanks for the reply T_G. I know the spec is 7 degrees, but I've read where these engines like 12 to 15 degrees. I tried all the way from retarded as I could get to advanced as I could get and it had no effect on my issue. I do have a timing / water pump kit on the way and will be changing it. And yes, the airbox is always on it now. Thanks, Robert
Well, for anyone in the future searching this type of issue, I can confirm 100% that it was my cam timing causing my problems. I put the new timing belt and tensioner on and it runs like a champ now - after re-tuning my carburetor and ignition timing. It's amazing what a difference it makes. I have full throttle now and throughout the entire rpm / throttle range, it's way more powerful. 95 kmh at part throttle is no problem now. He's a happy kamper kei-tora now. Sincerely, Robert
