First, naturally, be sure the fuel cap is tight. This system can be very difficult to diagnose without special equipment. Professionals will often use a "smoke machine". That will force a white, non-toxic smoke into the system under about 2 pounds of pressure. Then you look for any signs of the smoke leaking out.
That one piece of equipment costs around $800.00 - 900.00 and is one of the reasons shops have to charge the rates they do. Investing in that type of equipment is also what allows the higher priced shops to find and repair problems faster which results in a lower cost to you.
Be aware too that a small leak is usually a pinhole crack in a hose or its connection. Loose fuel caps result in large system leaks and will set the appropriate fault code. Chrysler uses a pump to put the system under a slight pressure, then a sensor watches how long it takes for that pressure to bleed off. The best you can do without the smoke machine is to visually inspect the hoses and their connections.
Thursday, March 11th, 2010 AT 4:07 PM