1986 Porsche 944 Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Fuel Pressure

  1. Locate fuel pipe cap nut at end of fuel rail. Remove cap being careful that sealing ball does not fall out. Connect a Test Pressure Gauge (P 378).
  2. Start engine and maintain idle speed. Pressure gauge should show 29.4 psi (2.06 kg/cm2 ). Disconnect vacuum line at pressure regulator. Pressure gauge should show 33.8-39.7 psi (2.37-2.78 kg/cm2 ).
  3. Pinch fuel return line of pressure regulator. Pressure gauge should show a minimum of 59.0 psi (4.13 kg/cm2 ). If fuel pump does not meet specifications, check fuel filter or replace fuel pump and retest.
  4. If engine will not start, check fuse No. 2. If okay, remove fuel pump relay "U" and bridge terminals No. 30 and 87b. Pressure gauge should show 33.8-39.7 psi (2.37-2.78 kg/cm2 ).
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

Shop Manual-Ready ToolsCompare Repair QuoteQuote Shield Pro

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

Rather have a pro handle this?

A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.

Comes to youSame-day available12-month warranty
Get a Free Quote

No obligation. See pricing before you book.