I am looking for some info on why a Toyota 7FGCSU20 on LPG runs with the air cleaner filter taped off. I was sent to this customer to service this forklift. I removed the air filter and seen that it was completely covered with packing tape. So I thought someone had tried to give the operator a bad time. So I removed the tape and completed the service. Moved the machine a short ways and all was good. A day later the customer was complaining about no power and would die if it had to lift a load. Another Tech went back to the customer and taped the filter up and the customer said the power is good now. This machine has to be getting air from somewhere or is the fuel so backed off that it won't run on full air.