check the cross over valve and lines they could be cloged maybe part of the fuel selector switch is bad I had this problem
Check selector switch and wiring take it to the shop and find out its probably old.
The traditional three port fuel selector valve is designed to allow the operator to switch between two fuel tanks, without having to switch the supply hose from one tank, to the other. Each of the two outboard, (outside) ports, go to your fuel tanks. The middle port is the outlet to your engine.
tank is built with two fuel drains, 1 normal use, second is reerve. when normal doesn't provide fuel, turn fuel selector valve to reserve position for the last 3/4 of a gallon of fuel in the tank. Look for the gas line coming out of the tank and it will go into fuel selector/cut-off valve. Most m/cs work this way.
There is no switch(other then fuse) the fuel pump is inside of tank. Try thumping the tank, it has been known to work other option replace fuel pump
Most vehicles with two fuel tanks have two fuel pumps. If the fuel gauge shows the reading in the front tank, the switch is most likely good, and the fuel pump is bad.
The sending unit is located on the fuel pump which is located inside the gas tank.
if it has a roll over switch it may be in the trunk over the fuel tank and it could be a fuse or relay if that doesn't work may be a bad pump.
If the bike is between an 1983 to 87 it does not have a reserve switch. It has an idiot light in the dash that tells you when you are on reserve. If it doesn't work you run out of gas.
it does not switch between cng and gas all the switch does is changes the dash board fuel switch to show how much gas in in your tank when you are running on CNG
check for a damaged fuel tank
Chevy does not have a reset switch. If you installed a fuel pump and it still won't work, Then you need to check the wiring harness at the pump where it plugs into the top of the tank. Chevy had a problem with the wire connector at that point.If that checks out okay, then check the fuel pump relay and fuse.