Need carb/fuel system help (long)
This isn't for a camaro...or even a car for that matter. Its for my tractor...but the general idea is still the same.
I've got a Satoh tractor that is about the same size as an old 8N ford. It has a 4 cylinder gas mitsubishi engine in it. 61 cubic inches, 19.5hp at 2300 rpms. I've had it for 3 years and it has been rock solid dependable (bought used). It has a regular old downdraft 1bbl carb...it is basically a low rpm car engine, and for what I use it for it works just fine. Anyway, this spring, I had carb problems with it, but due to my work schedule and location (only home 1.5 days every other week) I hadn't been able to fix it. I finally tackled it yesterday...figured out the carb problem (spring loaded needle/seat...the spring appears to have collapsed and it fell out). I got it all back together and got it running, but it would only run above 2000 rpms and only with the choke 3/4 closed. I first suspected a vacuum leak, and there was one at the carb baseplate. Corrected that, and it got a little better but still wouldn't run any less than about 1700-1800 rpms, and still had to have at least 3/4 choke. I tore the carb down and blew out all the passages and cleaned it inside and out real good. It run better yet but still wouldn't run under 1500 rpms and still needed 1/2 choke to operate even fully warmed up. I tore down the carb again...found that the main jet was partially plugged (it has a very weird jet...1 hole on the topside like a normal jet, but it divides into 2 slots out the bottom side). Cleaned that out, and replaced the inline fuel filter which was considerably nastier inside than in appeared (I cut it open...its just a regular 3/8" in/out clear plastic automotive type inline filter). Now I've got a rock solid idle at 500 rpms, but it also runs hot when trying to brush hog at 2300 rpms (lights the temp gauge after about 15 minutes use) with it and it has never done that before. I did notice that with the old fuel filter (which is below tank level between the tank and fuel pump) it always stayed completely full of full when running. This new fresh fuel filter only stays 1/2 full...right even with the in and out sides(it sits parrallel to the ground). My thinking is now that the fuel pump is weak...does that sound about right? I also added a new air filter and spark plugs. The engine is in excellent shape...no blowby or funny noises, and it starts super easy every time.
Finding parts for this thing is a nightmare. Its a japanese import from the '70's. If you all think that the fuel pump is weak then I will probably just install an electric pump.