After having poor performance, No acceleration after 50% throttle, I decided to clean out the entire propane system. Regulator, Vaporizer (ended up replacing) and Carbuerator. It is running Great now but now it idles high. High to the point where, when you let go of the brake, it begins to move. I have adjusted the Idle screw on the Carb to the point where the spring is totally compressed and I don't have much more room to back out the screw on the idle adjustment on the throttle. What else can I do to turn it down a bit?
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check return spring is present and dash pot solenoid (vacuum valve) is operating properly.
Check and make sure the air screw is in. I have seen them back out and get lost causing fast idle.
I checked the cables and tried the adjustment screws with no success. Next step I guess is to open the Carburetor back up. I did notice that there seems to be some lateral play in the throttle shaft. Not sure if it's supposed to be there. I was looking at the Diagram provided by impco and was looking at the Idle cutoff Piston and spring. I remember this was pretty gummed up when I cleaned the carb. Does that part have something to do with this issue.
I was just looking at where the throttle cable attaches to the plate on the side of the carburetor and I'm wondering if I need to readjust that. I noticed while I was adjusting the idle/ throttle adjusting screw that it wasn't able to go back to home position unless I put pressure on it with my finger. The engine actually sounded better when I did. I was thinking that maybe the throttle cable was too tight. Could I be on the right path? I will also look into your suggestion as well. I am an amateur at best. Learning as I go.
Something must be wrong with the throttle plate and/or throttle plate shaft in the carburetor where it can not close properly. The VVF30 is a vacuum operated lock off valve that is used to turn the fuel on or off.
Vaporizer M# Impco Cobra Type J CB-30712-001
Regulator M# Impco VFF30 S# 000414
Carburator M# Impco CA55-577-3 S# 000208
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