 Wiring new fuel pump for carb conversion |
|
|
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
|
| mb914 |
 Mar 16 2026, 11:48 AM
Post
#1
|
|
Newbie  Group: Members Posts: 2 Joined: 12-March 26 From: manhattan beach Member No.: 29,292 Region Association: Southern California  |
Hi All,
I recently installed an engine with carburetors on a 2056. I am trying to use the stock FI wire to power the pump. I read where you need to jumper a cable from pin 30 to 87 on the fuel pump relay. I did that but I am getting constant power to the pump when the key is turned off. Any tips on how to wire the pump so that it only turns on when the key is turned on? |
   |
 
|
  |
Replies
| GregAmy |
Mar 16 2026, 12:16 PM
Post
#2
|
|
Advanced Member Group: Members Posts: 2,647 Joined: 22-February 13 From: Middletown CT Member No.: 15,565 Region Association: North East States 
|
Circuit 30 is direct to the battery, so no surprise there. Instead, leverage the stock fuel pump relay.
Circuit 85 is keyed power and Circuit 86 is the solenoid ground to the computer. If you ground the Circuit 86 wire coming from the relay plate, wire III on the T4b plug, then the fuel pump will only be energized when the power supply relay is energized, thus only with the key on. Do note that one of the safety features of the stock system is that it will not energize the fuel pump if the engine is not running. So, for example, your fuel pump turns off in a crash and you're upside down with the engine stopped but have not yet turned off the key. You lose that protection when you have your fuel pump on with the key on. |
|
|
|
Posts in this topic
mb914 Wiring new fuel pump for carb conversion Mar 16 2026, 11:48 AM
mb914 Thanks for the help Greg. For some reason when I g... Mar 16 2026, 07:16 PM GregAmy For some reason when I ground wire III on the t4b ... Mar 16 2026, 07:51 PM |
2 User(s) are reading this topic (2 Guests and 0 Anonymous Users)
0 Members:
|
Lo-Fi Version | Time is now: 17th March 2026 - 04:24 AM |
Invision Power Board
v9.1.4 © 2026 IPS, Inc.