Expert: Robert Summers - 5/3/2009

Question
I have a Z71 that has been a great truck up till recently...  the truck would turn over but not start...  battery voltage (for the dash readout) appeared low (but again the truck was turning over fine...  I did notice the fuel pump "sound" was not present...  had it towed home... seemed to start again the next morning (I heard the fuel pump this time)...  I didn't drive it since I don't want to be stranded again...let it run a bit, then tested again and again...it stopped working again (no fuel pump sound, and low battery volts)  fuel pump is original as well as probably the fuel filter... 125K I know that's a lot on those parts, but the problem seems to be related to the battery voltage (I just don't want to drop the tank or lift the bed if it's just something like a bum battery (weak or dead cell)...  Charged the battery and now she starts again (but the pump does sounds odd)...  could a weak or dead cell in a battery cause such symptoms (i.e. turns over relatively fast (shows a couple hundred rpm on the dash) yet does not energize the fuel pump I don't know that for a fact, just speculating)

thanx,
mj

Answer
Hi MJ....change the pump....a lot of times when they quit if you have truck towed or bump the tank the pump will start working again...the pump will run till the battery quits, there is no low voltage shutdown....it will get weak but fuel pressure regulator controls pump pressure....if you turn key on you should hear pump run for 3 seconds... if it doesn't replace pump.... hope this helps