ALTERNATIVE FUEL SYSTEMS, INC.

  ANSWERS TO FREQUENTLY ASKED QUESTIONS

The #1 question asked since fuel costs started increasing daily.

Q: Will I save money on fuel by converting my car or truck to propane?

A: Yes, but the amount of savings is dependent on many factors. The following are important points to consider when deciding how cost effective the conversion would be.

• The cost of the conversion. Currently this is about $2000.00 plus $500.00 for the fuel tank.
• The price of propane versus the price of gasoline. Current prices are about $4.00 per gallon of gasoline and about $3.00 per gallon of propane. A savings of $1.00 per gallon. This price differential appears to be consistent regardless of the increase in the price of gasoline. This looks attractive.
• Current miles per gallon rating of your vehicle. Due to the chemical makeup of propane you can expect a 10% to 20% reduction in fuel economy.
• Age and mileage of vehicle to be converted. You must be able to drive the vehicle long enough to offset the expense of the conversion. If you average 12,000 miles per year, and average 15 miles per gallon, you will use 800 gallons of propane per year at a cost of $2,400.00. If you average 12,000 miles per year, and average 17 miles per gallon, you will use 705 gallons of gasoline per year at a cost of $2,820.00. This represents a savings of $420.00 per year. At this rate it will take approximately 6 years or 72,000 miles to break even.
• Of course all of these variables change depending on current prices, your vehicle and the amount of time you spend on the road. If you have an economical vehicle, drive more than 12,000 miles annually, or the gasoline to propane differential widens, it may be a good choice for you. If your vehicle already has poor fuel economy and / or  high mileage, you drive 12,000 or less annually, or gasoline and propane prices move in tandem, you may want to reconsider.

Q: Are Propane Tanks rated at a higher pressure than CNG Tanks?

A: Propane cylinders are rated at 312 P.S.I. The walls of the propane cylinder are approximately 1/8" thick.  CNG tanks are rated at 3600 P.S.I with 1" thick walls. Under NO CIRCUMSTANCES may a propane cylinder be used for CNG!

Q: How can I see what Impco or AFS carburetors match the air flow requirements of my
personal vehicle?

A: Click on this link and look at pages 44 & 45. troubleshooting manual

Q:My forktrucks currently run on propane.  Do I need to change any components other than the
storage tank (ex. CNGTM 1) in order to convert to CNG?

A: Yes, you will need to change most of the components. The storage tank for CNG (ex. CNGTM1) is not only a storage tank, but includes a high pressure regulator. This regulator reduces the CNG pressure from 3600 P.S.I. to 150 P.S.I. which is the normal pressure of propane. The converter used under the hood for a CNG system is also different than an LP converter. An LP converter works on negative pressure. The vacuum from the engine draws the fuel from the converter. The converter in a CNG system is a pressure converter. It cannot be used for propane. The carburetor used for CNG is usually changed as well. Since CNG runs more lean than propane, it is necessary to at least change the air valve of the carburetor to allow a more rich fuel mixture. Changing to a CNG system is actually a complete fuel system change.

Q: How often should an LPG fuel system be serviced?

A: It depends on how many hours per day, and how many days per week your truck is used. For a general guideline, please see our Technical Support page

Q: On a post 2004 certified system, is there a repair kit for the converter, or replacement diaphragm for the carburetor?

A: No, Fuel Control and Trim valves may be replaced, but any internal components including seats and diaphragms are not able to be replaced. The entire converter or carburetor must be replaced.

Q: Can I convert a post 2004 gasoline forklift truck to propane?

A: No, due to C.A.R.B and EPA restrictions all propane fueled lift trucks manufactured after 2004 must come from the factory with certified tamper resistant systems.

Q: Can I get a Model JB or Cobra converter with a primer button?

A: No, the primer button was discontinued on all Model J and Cobra converters in 2005. Due to priming not being necessary, and a possible problem in Europe, the button has been permanently eliminated.

Q: The primary valve on my Model J has failed, and upon inspection it has been found to be cut. Is this a defective part?

A: No, If the primary valve on a Model J converter is cut, it is not a defect and is not covered by warranty. Primary seat damage is caused by over-pressurization of the converter. Normal primary pressure is 1.5  P.S.I. At 1.5 P.S.I. the seat cannot be damaged. Over-pressurization is caused by either contamination of the seat / orifice, or freezing of the converter. Contamination of the seat can be caused by either contaminants in the fuel, foreign matter, or heavy oils from impurities in fuel. Freezing of the converter can be caused by either lack of sufficient coolant to the converter, or starting the truck and turning off before reaching operating temperature. Either of these two conditions will cause the primary pressure to increase beyond 1.5 P.S.I. and damage the primary seat.

Q: When I remove the carburetor hose from the Model J or Cobra converter, no fuel comes out. Is the converter bad?

A: Probably not. The Model J and Cobra converters work on a demand principle. They are negative pressure converters. The intake vacuum of the engine draws the fuel out of the converter. In fact, if you remove the hose and fuel is escaping, then the converter is bad.

Q: There is a great deal of thick oil in my converter. What is this, and how can I prevent it?

A: The thick waxy oil found in converters is caused by impurities in the propane. Propane was not intended as a motor fuel and hence is not regulated as to its contents. The actual contents in propane can very widely from one source to another. It can even very from the same source from one day to the next. These impurities can settle out in the converter when the converter temperatures are high. Optimum vaporization of LPG occurs just below 140° Fahrenheit. At temperatures higher than this, the fuel begins to re-refine in the converter. This process causes the heavy oils to stay in the converter and deposit on the critical internal components of the converter. Engines normally run in excess of 180° Fahrenheit. Uncontrolled, the converter temperature will near engine temperature. AFS offers a thermostat device that uses the natural refrigeration action of vaporizing fuel to keep the converter temperature below the 140° Fahrenheit threshold.

Q: Can you park in underground parking lots with a car that has been
converted to propane?

A: Yes, you can, but only if your windshield bears a special tag issued by the installing company. If you are a tenant in a building, check your lease or condo agreement to make sure it is allowed by the building's owners.

Q: Can you convert personal vehicles to run strictly off propane?

A: Yes. The majority of personal vehicles that are converted are configured to run on either gasoline or propane. Propane is not as readily available as gasoline. If your vehicle is dedicated to running on propane only you may be in a situation of running out of propane and not having a convenient place to refuel.