Cadillac Repair: gas, fuel pump relay, rubber mallet

Question
I have 1 91 sedan deville that my husband let it run out of gas.  Now it will not start even after putting gas in it.  If you pour gas directly into the carburator it will fire but then cut off.  I have heard you are not suppose to let them run out of gas.  What can I do? HELP!!!!!

Thanks

Answer
Hi Martha,

       Sounds like the fuel pump was starting to fail and not having the gas in the tank to cool it caused the pump to bind up and need to be replaced. It is also not uncommon for a pump that is failing to do so after the cold gas gets to it after filling the tank. The shock of cold gas on a hot pump does it in.

       There are several things to try before replacing the pump. First get a helper and remove the gas cap. Then turn the key on to light all the dash lights and listen for the fuel pump to make noise for 2 seconds and then quit. If no noise listen for the fuel pump relay that is behind the glovebox area to click. You need to turn the key off and wait 5 seconds before turning the key back on or the computor won't turn on the relay. If no click you could try replacing the relay with one from a different location that has the same part number and then try the key again. If it works now get a new relay and listen for the pump to work.

      In the rear of the engine compartment on the passenger side behind the plastic panel there is a short red wire with a green connector on it. If you make a jumper wire from that to the battery positive cable bolt the fuel pump should also run and it won't matter if the relay is good or not. If you still don't hear the pump with the key on and that wire jumpered then take a rubber mallet or smaller hammer and tap or the bottom of the gas tank in the middle. You don't want to hit it so hard that the tank is dented but after 5-6 hits it can jar the pump into working. Most times though it just means that you won't have to push the car or have it towed to the shop because it might run for 30 seconds or 30 minuets and quit...there really isn't any way to know for sure.

     The short answer is that if the pump has never been replaced or has more than 80,000 miles on it then it is probably bad and needs to be replaced by your mechanic along with the fuel filter and strainer inside the tank. Doing this job at home is kind of dangerous because you need to sifon the gas out of the tank into gas cans and then the fuel lines or bolt might be so rusty that they won't come apart without air tools or having the car high enough in the  air for better access. Bill