I have a 94' Sedan Deville. A good size rock had bounced under the chasis to the car while driving and immediately the gas guage dropped to 14 gallons and will never read full after a fill up, 14gl max. Also in the first 5 miles of driving the computer will scroll " engine hot- engine coolant hot- a/c compressor off" for 1 minute then everything goes back to normal. I have taken it in to be checked but when put on the diagnoses machine no faults come up. I have not been able to bring it in when the dash is going hey wire. Mechanic said everything in the cooling system is fine. Anyonehave any ideas on what is happening and how to fix. I have beenout o work due to writers strike and really don't have the $ for a mechanic to test it for hours or a day at $60 an hour. Thank you.

 

Inspect underside of car looking at everthing. If rock was large enough it could damage fuel module/sender assembly. It is spring loaded against bottom of plastic fuel tank. Engine hot - code(s) should be stored, Check coolant level, possibly sticking thermostat, also check condition of water pump belt and pulleys. Nylon drive pulley will appear to be melted if tensioner or pump is starting to lock up.