I tried Colman fuel on my Fuji BT-32B and my Zenoah G62 with C & H Electronic Ignition. Both engines ran fine with the Colman fuel and Evolution Synthetic oil mixed 35:1. I have on the BT-32B a relay kill switch that shorts the magneto and on the Zenoah G62 I have a electronic kill that turns off the power to the ignition box. When trying to shut down the engines both just kept running. To get them to stop I had to pinch the fuel lines. I found that if I pumped about 1 oz. of regular gas into the planes before filling the rest of the tank with the Colman mix the engines would then shut down properly.
Any ideas as how to fix the problem? I do not want to fly with a engine that will not shut down properly. I use the fail safe to kill the engine in the case of a failure.
Dear Mr. K-,
This is the first time I have heard of anyone having a problem using Coleman fuel. Evidently, your engines are running very hot and the Coleman Fuel is “dieseling” due to the low 60 octane rating. First off, be sure the carburetors are shutting off completely. This should lower the idle speed low enough to kill the engines. If not, install a fuel cut off system. There are two ways you can go here. The easiest is to get a smoke valve used to turn smoke on and off and use it as a fuel cut off. Conley Precision Engines.com that now make the Perry carburetors and pumps have one as does Du-Bro, and others. The other method is the same as we used to use on the Formula I Pylon engines. Make a hairpin loop out of 1/32″ piano wire and drill matching holes in the firewall. Connect to a servo and feed the fuel line through the hairpin loop. Squeezing against the firewall shuts off the fuel.