1. Try adjusting the load-block. For Natural Gas 7-9 turns is a good starting point. It may take more or less turns than that. If the adjustment is off by even one turn, it can cause this issue. Most likely you will need to turn the adjustment counterclockwise if you are having to hold the primer button in.
2. Make sure there are no vacuum leaks.
3. Make sure all of your line sizes and fitting sizes are large enough by looking at the Natural Gas Pipe Sizing Chart on our website: http://uscarb.com/natural-gas-chart.htm You may also need to check with your natural gas company and make sure that you have enough volume and pressure. Please make sure you do not have any fittings or valves in the system that may be causing a restriction. Ball valves with red or yellow handles are notorious for being restrictive. Only full bore ball valves should be used.
4. If using a snorkel kit make sure the probe of the snorkel is not kinked inside of the carburetor. Also the snorkel probe should end exactly in the center of the carburetor where the brass gasoline jet comes up through the center of the carburetor. If it doesn’t please let us know.
If using the adapter kit make sure the arrows on the sticker are pointing towards the carburetor and that the adapter is between the carburetor and air cleaner.
5. Some engines especially that are a couple of years old may need the valve lash adjusted. This should be done according to the owners manual. Most engines require this every 12 months or 300 hours which ever comes first. When the valve lash is out of adjustment you will not have as much engine “vacuum” to keep the demand regulator in our kit open.
6. If the engine still will not run without holding in the primer button, please send pictures of your complete setup from where the fuel begins to the kit on the generator to: firstname.lastname@example.org