Fuel Pressure Specifications:
The fuel pressure for a 1995 LT1 should be between 39-45 PSI (pounds per square inch) at idle. This pressure is regulated by the fuel pressure regulator, which is part of the fuel rail. You'll need a fuel pressure gauge to check this. Do not attempt to check fuel pressure without the proper safety precautions, including eye protection. Fuel is flammable and under pressure.
Other Potential Causes (more likely than a just a slightly weak fuel pump for a light stumble):
* Dirty MAF sensor: This is a common cause of drivability issues, especially under light load. Cleaning or replacing the Mass Air Flow sensor often solves these problems.
* Faulty TPS (Throttle Position Sensor): A malfunctioning TPS can cause inconsistent fuel delivery.
* Vacuum leaks: Small vacuum leaks can disrupt the air/fuel mixture. These are harder to find but can make a big difference.
* Ignition issues: Worn spark plug wires, bad spark plugs, or a failing ignition coil pack can lead to misfires, resulting in a stumble.
* Dirty injectors: Clogged fuel injectors can restrict fuel flow.
* Faulty PCM (Powertrain Control Module): While less likely, a problem with the computer itself can cause all sorts of drivability issues.
Troubleshooting Steps:
1. Check fuel pressure: As mentioned above, this is a crucial first step. If the pressure is significantly below 39 PSI, then a fuel pump issue is more likely.
2. Inspect fuel filter: A clogged fuel filter can restrict fuel flow, mimicking the symptoms of a weak fuel pump.
3. Check for vacuum leaks: Listen carefully around the intake manifold and vacuum lines for hissing sounds.
4. Inspect and/or replace spark plugs and wires: This is a relatively inexpensive and easy maintenance item that often solves problems.
5. Clean or replace the MAF sensor: This is usually a simple fix that yields good results.
6. Check the TPS (Throttle Position Sensor): This may require a scan tool or multimeter to test voltage readings.
In short: While a weak fuel pump *could* cause a stumble under light acceleration, it's far more likely that other, more easily diagnosed problems are the root cause. Systematically check the items listed above before assuming the fuel pump is the culprit. A fuel pressure test is a good place to start, but it's just one piece of the puzzle.
