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Have to beat gas tank to get 2000 Silverado 1500 started!

Help! I have a 2000 Silverado 1500. Out of the blue, for no reason it won’t start. New battery, full of gas, no obvious problems. Always maintained.
When it won’t start–you have to get a big stick or piece of rebar and beat on the gas tank and most of the time it will start. I have had 5 new fuel pumps! New electronic ignition switch( that was the Chevrolet dealership’s diagnosis). Nothing works–the problem ALWAYS resurfaces. Someone must know the answer! I stopped reading the internet about this problem after 39 pages. I am desperate. I love my truck–but I am a single, 5’ tall ranch owner and I need my truck to work all the time. I do have a car, but that is not for hauling supplies, etc. Please help! Thanks!

Just curious, how did you come to figure out that beating on the gas tank seemed to help it start?

And who first disgnosed a bad fuel pump? I’m thinking, if you’ve had 5 new fuel pumps and the problem is still there, it’s probably not the fuel pump that’s at fault.

Sometimes car problems can trick us into mistaking coincidence for causation. If you beat on the starter, say, instead of the gas tank long enough, the truck might start then, too. Not saying beating on the gas tank is merely coincidental with the truck starting, rather than causative, but it’s a bit puzzling…

Have you had someone do a pressure test on the fuel system when the truck is not starting? That would help confirm whether or not the gas tank/fuel pump is at fault. If not, you can stop beating the tank and look elsewhere for the problem…if yes, someone should be able to figure out what’s wrong in the fuel system.

I would make sure you have a good connection to your fuel pump. Maybe every time they replaced it, them wiggling the wires made it work. Maybe a bad ground. You pounding on that tank may just ‘fix’ the connection.
Put a volt meter on the thing when it doesn’t start and see if you see a voltage when you turn the key. You should see 12V for a brief 1 second time interval when you turn the key just before start.

My guesses would be either a poor fuel pump wiring connection or something totally unrelated to the pump (crank sensor, etc, etc) that is being jolted into operation by the tank banging.

Replacing a fuel pump 5 times is really grasping and you have not stated if the truck has been scanned or not and if so, what codes if any are present.

I agree. Last I checked fuel pumps are not changed like oil filter intervals. Something else is going on.

Have you checked the fuel pressure and fuel pressure regulator? Harbor Freight has a universal pressure test set cheap. Be careful when working with fuel systems!!! You may start a fire!!!
Have you replaced the fuel filter? I believe some systems have 2 one in the tank and one someplace else.
If Possible check the voltage at the fuel pump. There can be as many as 6 wires going to the pump.
You need to get a manual and check the fuel pump relay and associated electrical ciruits.
cubpilot

Could it be caused by a clogged filter inside the fuel tank on the fuel pickup thingy? I had an '80 Intl. Scout that had a clogged filter and it would slowly lose power and die, wait a little while and it would run again. Not exactly the same problem as yours but I tried everything under the sun before finding that little fault.

I cannot thank you all enough for your suggestions which I will promptly take to the mechanic. The truck was towed to his shop yesterday afternoon. Let me clarify some things: 1. One of my farmer friends suggested that I hit the gas tank to see if it would start because he could not hear the fuel pump when trying to turn on the truck.
2. The truck was scanned by a Chevrolet dealership–they told me to replace the electronic ignition switch, which I did. Made no difference at all. 3. My mechanic is excellent and has check all wiring possible. I most certainly will take all of your comments to him. I am not sure that he has put a voltage meter or regulator on it (this is when I start to get lost as I do not know much at all about engines, etc.)

I am scared to death to keep hitting the gas tank–I am afraid the police will think I am trying to damage someone else’s vehicle. It is so embarassing to have to get out of the truck and start hitting the gas tank.

Please keep the comments coming–I will be reading all of them! I am so grateful to you all for taking the time to answer my questions and help me.

No pump operation when the key is first turned on (no engine cranking by the starter motor) could point to a faulty pump relay or problem with the PCM.
Generally speaking, a pump relay is energized by a momentary ground or power source trigger for a few seconds when the key is first turned. Without engine cranking this ground or source disappears quickly but will be maintained if the engine is rotating courtesy of the starter motor.

A look at a schematic shows the pump relay receives a power source from the PCM to energize the relay when the key is turned so the first thing that might be checked is to make sure that power source for the pump relay trigger (NOT the main power source for the relay) is good.
There’s also a fuel tank pressure sensor which provides input to the PCM but since this gets into the internal circuit board function of the PCM it’s unclear to me whether or not the FP sensor has any affect on the pump relay trigger circuit.

Hope some of that helps anyway.