ProtoCab

Hi all,

The subject heading says it all... I'm trying to find a good steady 12v source that's hot only when the engine is cranking & running. Somewhere in the engine bay preferred.

My rear fuel pump is currently wired to Ignition ON, so it's buzzing when the key is switched to on. Damn annoying! I need it to turn on *only* when the engine is cranked and running (like the front pump, which gets powered from the DME relay).

Anyone got any suggestions?

Thanks in advance

Droops83

Rear fuel pump? Sounds like you have a 930. If so, check on the 930 board. But I will give you one tip: reach around the back of the fuel distributor and check that the connector for the airflow sensor plate switch is hooked up. If it is unplugged, the pumps will run all the time w/ the key on; plugged in, only while cranking and running . . .

---Chris A.

ProtoCab

Thanks Chris. I actually have a 1989 Carrera, however, it has been turbocharged and runs a rear BOSCH 044 fuel pump in series with the front 044 pump

So, my question is actually Carrera specific

Lorenfb

"I actually have a 1989 Carrera, however, it has been turbocharged and runs a rear BOSCH 044 fuel pump in series with the front 044 pump "

You need to wire another relay (4 pin) off of the stock DME relay to run the other fuel pump.
It's not a good idea to have a pump running without the engine running.

ProtoCab

Thanks Loren... that's why I want to re-wire it to only run when cranking/running. I'll look into wiring in a second DME relay in parallel.

Lorenfb

A second fuel pump relay can wired different ways:

First, use a common four pin relay with the pins; 30, 87, 86, 85 with
30 connected thru a fuse to a main constant power (#30) and the
87 pin connected to the fuel pump and either:

1. connect the 85 to ground and the 86 to the original fuel pump power or,
2. connect the 85 to the 30 pin and connect the 86 to the DME relay 85a.

ProtoCab

Great info! Thanks Loren

You wouldn't have a part # of that 4 pin relay handy, would you?

2.7RACER

911 615 108 01, Standard Type Relay, Red.

ProtoCab

Cheers

Lorenfb

The best relay is:

Bosch 0 332 014 406 - 12 volts/30amps