Thanks for the info. During the restoration of Big Yellow, and aftermarket sender unit was used. When the tank is filled, it shows as being full. After about 50 miles, the gauge moved down to empty. Obviously, we are not out of fuel. That seems to point to the sending unit which might possibly be the wrong one for the car! I will change when a suitable replacement is found, but I am going to run the suggested test out of curiosity. As always, thank you again for your time and dedication. 300F'ly, Louis M. Barrie West Hills, CA Home of Big Yellow -----Original Message----- From: John J. Hertog [mailto:crossram@xxxxxxxxxxxxx] Sent: Saturday, April 29, 2006 6:37 AM To: lmbarrie@xxxxxxxxxxxxx; chrysler300@xxxxxxxxxxxxxxx Subject: erratic fuel gauge readings On Behalf Of Louis M. Barrie Sent: Friday, April 28, 2006 8:39 AM Um...A gas tank gauge that is accurate? Who has had experience with rebuilt / reproduction fuel sending units for the 300F and what works best? Louis, As far as I know, there are no "good" reproduction sender units for our cars. Some years ago, I had ordered a repro from some outfit on the East Coast, can't remember the name, and I was not too pleased with it. If dealing with inaccurate fuel gauge readings, first step in diagnosing what is the cause of the problem. It is not necessarily the sender. 1/ remove sender unit from tank (relatively easy job, as long as tank is less than 1/2 full) . Check first for fuel INSIDE the float - this will happen more often than you think. If the float is OK, using ohmmeter, measure resistance from full to empty, by moving the arm. Should read between 10 Ohms and 72 Ohms, something like that. Any variations or dead spots, the sender needs rebuilding. Jeff Carter does deal with those. 2/ If sender checks out OK and float is good, reinstall. Make sure the sender is properly grounded to the fuel line via the relevant strap. If need be, run a jumper wire from sender body to ground and check operation that way. 3/ if still erratic / inaccurate readings, check multi-plug between front and rear wiring harnesses for corrosion (located behind front kick panel) Next, either the gauge on dash is bad, or the voltage regulator portion of the OIL PRESSURE gauge is bad. If the output of the oil psi gauge regulator is too high or too low, it will affect the readings of the temp gauge AND the fuel gauge. John Hertog Sag Harbor NY [Non-text portions of this message have been removed] To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/