What should fuel pump pressure be with the engine running?

There's no single answer to what fuel pump pressure should be with the engine running. The correct fuel pressure varies greatly depending on the make, model, and year of the vehicle. It also depends on the engine's specifications and even the specific fuel injection system used.

To find the correct fuel pressure for your vehicle, you need to:

1. Consult your vehicle's repair manual: This is the most reliable source. The manual will specify the correct fuel pressure range for your car's engine and fuel system.

2. Check online resources: Websites specializing in automotive repair information (like those for specific makes and models) often have specifications, but always double-check against your repair manual.

Attempting to determine the correct pressure without consulting your vehicle's specifications is risky. Incorrect pressure can damage your engine.

Important Note: Fuel pressure is typically measured using a fuel pressure gauge. Improperly using a fuel pressure gauge can be dangerous due to the flammability of fuel. If you are not comfortable performing this task yourself, take your vehicle to a qualified mechanic.