If you have to hit the bottom of fuel tank with a hammer start 1990 Chevy van G20 does that mean change pump?

Not necessarily. Banging the fuel tank with a hammer is sometimes done as a temporary fix to get a fuel pump working again, but it is not a long-term solution and does not mean that you need to change the pump.

Here are a few reasons why you might need to hit the bottom of the fuel tank with a hammer:

1) Clogged fuel filter: A clogged fuel filter can restrict the flow of fuel to the engine, causing it to stall or run poorly. Hitting the bottom of the fuel tank can dislodge the clog and allow the fuel to flow freely again.

2) Faulty fuel pump: A faulty fuel pump can also cause the engine to stall or run poorly. Hitting the bottom of the fuel tank can jar the pump and get it working again, but this is only a temporary fix.

3) Loose electrical connection: A loose electrical connection can also cause the fuel pump to stop working. Hitting the bottom of the fuel tank can vibrate the connection and get it working again, but this is also a temporary fix.

If you have to hit the bottom of your fuel tank with a hammer to get your vehicle started, it is important to take it to a mechanic as soon as possible to have the problem diagnosed and repaired. Driving with a faulty fuel pump or a clogged fuel filter can damage your vehicle's engine.

Here are some additional tips for starting a vehicle with a faulty fuel pump:

- Try turning the key to the "on" position for a few seconds before starting the engine. This will allow the fuel pump to prime the system.

- If the vehicle does not start, try hitting the bottom of the fuel tank with a hammer.

- If the vehicle still does not start, you may need to have the fuel pump replaced.