FPCU Bypass (2x2)

If your Fuel Pump Control Unit is giving you trouble or you suspect it is, you can bypass the it as a temporary solution to get you home if it fails while you're out and about (as it usually does), or to diagnose the FPCU as the root of a non-starting/poor-running condition. The FPCU changes voltage by limiting the ground-side of the signal, so bypassing the FPCU simply requires a direct ground connection to the line which would otherwise be limited, supplying battery voltage to the FPCU under all conditions.

Please note that while many owners have driven on their cars for as long as a year with the FPCU bypassed, it should be done as a temporary solution, as this can put excess strain on the fuel pump and fuel pressure regulator.

Original writeup from Aus300ZX.com.

This article is for the 2+2 (four seater) Z32. For the 2-seater, see FPCU Bypass (2-Seater).

Bypassing

Parts Needed

• 1 eyelet connector.
• A few inches (maybe a foot) of wire.

Tools Needed

• Philips screwdriver.
• 10mm socket/ratchet.
• General electrical tools (scissors, crimper, soldering iron, etc).

Procedure

First, you need to gain access to the FPCU.

Nevermind that this picture shows a 2-seater >_>

1. Remove the rear seat.
2. Remove interior panel behind the rear passenger seat on the driver's side.
3. Disconnect the connector for the FPCU.
4. Locate the white wire.
   • There are actually two white wires. One of them is naked, and the other is covered by a black sheath. We are concerned with the naked one--ignore the one with a black sheath.
5. Cut away some of the insulation on this white wire, and splice into the wire with your new wire. Use solder or a vampire clip.
6. Wrap the new splice with electrical tape or something similar.
7. Connect the eyelet to the other end of your new wire.
8. Connect the eyelet+wire to a ground. One of the nearby mounting points for the FPCU work great.
   
   

   Click for full-size.
9. Reconnect the FPCU connector to the FPCU.
10. Enjoy~!