Here's a breakdown of how to approach this:
1. Listen for the Fuel Pump:
* Key On, Engine Off (KOEO): Turn the ignition key to the "ON" position (don't start the engine). You should hear a brief whirring sound from the fuel pump in the fuel tank. This usually lasts for a couple of seconds. If you don't hear anything, the pump *might* be bad, but there could be other issues (blown fuse, faulty relay, etc.). This is the easiest and quickest initial check.
2. Check Fuel Pressure:
* This is the most definitive test. You'll need a fuel pressure gauge and the correct adapter for your Trailblazer's fuel rail. Consult your owner's manual or a repair manual for the specific fuel pressure specifications for your engine. This requires some mechanical aptitude.
* Disconnect the fuel line: Carefully disconnect the fuel line from the fuel rail to attach the gauge. Be prepared for fuel to spray out. Have rags ready to soak it up.
* Turn the ignition on: With the gauge connected, turn the ignition to the "ON" position. The gauge should show the specified pressure. If the pressure is low or nonexistent, the fuel pump is likely the culprit. If the pressure is good, the problem lies elsewhere in the fuel delivery system.
* Important Note: Always relieve fuel pressure before disconnecting any fuel lines. Failure to do so can result in injury from spraying fuel. Consult a repair manual for proper pressure release procedures.
3. Inspect the Fuel Pump Relay:
* Locate the relay: Consult your owner's manual to find the location of the fuel pump relay. It's often in the underhood fuse box.
* Visual inspection: Check for any obvious signs of damage, such as corrosion or burnt contacts.
* Swap the relay: If you have a spare relay of the same type, try swapping it with the fuel pump relay. If the problem is solved, you know the original relay was faulty.
4. Check the Fuel Pump Fuse:
* Locate the fuse: Your owner's manual will show you the location and amperage of the fuel pump fuse.
* Inspect the fuse: Check for a blown fuse (broken filament). If blown, replace it with a fuse of the same amperage. If the new fuse blows immediately after replacing it, there's a short circuit somewhere in the system.
5. Check for Low Fuel:
* A seemingly faulty fuel pump can sometimes simply be caused by very low fuel in the tank, as the pump may not be able to draw sufficient fuel.
When to Seek Professional Help:
If you're not comfortable performing these checks, or if the problem isn't easily identified, it's best to take your Trailblazer to a qualified mechanic. Working with fuel systems requires caution and expertise. A misdiagnosis can lead to further damage or injury.
Remember safety first! If you are not comfortable working on your vehicle yourself, it is always best to consult a qualified mechanic.
