Fuel Pump Delivery Rate – Checking

Overview

This procedure checks how much fuel the pump delivers in 30 seconds on your Porsche 944 S / S2 with its 16v engine. It’s important to ensure the fuel system is working properly, as a weak pump can cause poor performance or starting issues.

Pink and blue text represents links to additional resources, tools, parts, and partner websites.

Tools Required

• Metric wrench set
• Measuring container (1500 ml / 50 fluid ounces or larger)
• Hose to connect to the fuel pressure regulator
• Hose clamp
• Stopwatch or timing device
• Catch rags

Step-by-Step Procedure

Step 1: Prepare for Fuel Spillage

Have catch rags ready to soak up any fuel that might spill. The fuel rail in your Porsche 944 S / S2 may be under high pressure, and removing lines too quickly can cause a spray.

Step 2: Disconnect the Fuel Return Line

Slowly disconnect the return line from the fuel pressure regulator (FPR) that leads back to the fuel tank. This is located near the fuel rail on the 16v engine. Take your time to avoid spraying fuel.

Step 3: Attach a Hose to the FPR

Use a hose clamp to secure a hose to the FPR’s discharge port. Make sure the hose is long enough to reach your measuring container safely.

Step 4: Remove the DME Relay

Locate the fuse/relay panel under the hood of your Porsche 944 S / S2. Remove the DME relay from this panel. This controls the fuel pump on late-model cars like the S / S2.

Step 5: Jumper the Relay Terminals

At the relay socket where you removed the DME relay, use a jumper wire to connect terminals 30 and 87b. The fuel pump will start as soon as you do this, so be ready to start your stopwatch. If you’re unsure about the terminal numbers, check the labels on the bottom of the DME relay.

Step 6: Measure Fuel Delivery

Let the fuel pump run for exactly 30 seconds, timing it with your stopwatch. After 30 seconds, remove the jumper wire to stop the pump.

Step 7: Check the Fuel Volume

Measure the amount of fuel collected in your container. For the Porsche 944 S / S2’s 16v engine, the fuel pump should deliver at least 850 ml (28.7 fluid ounces) in 30 seconds. If it’s significantly less, there might be an issue with the fuel pump, fuel filter, or fuel dampener.

Post Procedure Checklist

• Check for fuel leaks around the FPR and hose connections.
• Ensure the DME relay is reinstalled securely in the fuse/relay panel.
• Dispose of any spilled fuel and rags safely.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manual, Volume 1
• Youtube