The check engine light is either red or orange. With a motor symbol in the middle. It flashes in a sequence to state the code.
The propane filter should be inline from the coupler to vaporizer. A secondary filter is in the vaporizer as well. You may have a blown high pressure seat internal in the vaporizer. We just replace the assembly vs a kit. It allows to much fuel and kills the motor. All parts are online @ toyota if you need oem.
Make sure the spark stays while cranking. After it quits. Maybe a bad distributor. Oem parts are 2 yr warranty From toyota. If you have spark then fuel. Take a pic of the dash and post it. Thanks