Fuel System Related:
* New Pump Installation: The most common culprit is an incorrect installation of the new fuel pump. Double-check everything:
* Wiring: Are all the wires connected correctly and securely? A loose or incorrect connection will prevent the pump from working.
* Ground: Is the pump properly grounded? A poor ground can inhibit operation.
* Fuel Filter: Did you replace the fuel filter? A clogged filter will prevent fuel from reaching the engine even with a new pump.
* Fuel Lines: Are the fuel lines free of kinks, cracks, or blockages? A leak anywhere in the line will prevent fuel delivery.
* Pump itself: While unlikely if it's new, it's possible the replacement pump is faulty. Though less likely, it could be the wrong pump for your vehicle.
* Fuel Pressure: You need a fuel pressure gauge to test the fuel pressure at the fuel rail. This will tell you definitively if fuel is getting to the engine. Low or no pressure points to a problem even after the pump replacement.
* Clogged Injector(s): Even with sufficient fuel pressure, clogged fuel injectors can prevent fuel from reaching the combustion chamber.
Ignition System Related:
* Distributor: If your Astro has a distributor, check the rotor, cap, wires, and coil for wear or damage.
* Ignition Coil: A faulty ignition coil won't create the spark necessary for combustion.
* Spark Plugs and Wires: Worn or fouled spark plugs or damaged wires will prevent a spark.
Other Possibilities:
* Security System: Some vehicles have immobilizers or anti-theft systems that can prevent the engine from starting.
* Neutral Safety Switch: The automatic transmission might not be in Park or Neutral, preventing the starter from engaging. (Applies to automatics)
* Starter Motor: The starter itself might be faulty and unable to crank the engine. Listen carefully – do you hear the starter motor engaging when you turn the key? A clicking sound often indicates a low battery or a bad starter.
* Battery: A weak or dead battery will prevent starting.
* Cranking issues: The engine might be cranking slowly or not at all.
Troubleshooting Steps:
1. Check the obvious: Battery voltage, connections, fuel filter (replace it regardless).
2. Listen carefully: Does the pump prime when you turn the key to the "on" position (but before cranking)?
3. Fuel Pressure Test: Rent or borrow a fuel pressure gauge and check the pressure. This is crucial.
4. Visual Inspection: Inspect all fuel lines for leaks or damage.
5. Ignition System Check: Have a mechanic or use an ignition system tester to check the spark plugs, wires, coil, and distributor (if applicable).
If you're not comfortable performing these checks yourself, take your Astro to a mechanic. They have the tools and expertise to diagnose the problem quickly and accurately. Providing them with the information that you've already replaced the fuel pump will help them focus their diagnostic efforts.
