Searched and found some stuff but no definate. Will it hurt anything for the fuel pump to be running a constant 12v. I have an s5 with an s4 TII in it and i was gonna wire the fuel pump directly to a 12v constant that turns on when the ignition is on (not on acc). Will this hurt anything when the car is idling or driving.

 

I don't think you'll notice it. It will cause the idle to be a wee bit richer ( I checked this out on another thread this year)but you won't notice it. I can see the change in afr on a wideband b/t 9volts at the pump and 12v at the pump by depinning the pin 3D and repinning it. I don't remember the change being noticable to the ear.

Fact is my 87non turbo/turbo conversion does not right now have a fuel pump resistor/relay (but I did buy one on EBay last week) so it's running approx 13 plus volts all the time. I've got a relay and a wire running from the battery to the relay which is located near the pump.

 

would it be better for me to hook the relay from the s4 engine up. Just patch it in to the new wires i ran.

 

i would, there are safety features to the resistor relay, besides dropping voltage at idle.

 

AS in it will shut the pump down in case of an accident.

 

Your series five has the fuel pump resistor relay package. I think you should do the Fuel Pump Rewire that is posted on this site somewhere.

That said, my series four has no fuel pump resistor relay assy. It did not come with one. I just added a relay back near the antenna and jack area.

I use the factory Blue wire to engage the relay, which then pulls in and passes voltage from the new wire that I ran from the battery all the way back to the new relay, to the fuel pump.

That arrangement means that I still have the safety feature of the original assy because if the afm switch fails to open then the pull in voltage for the NEW relay won't be there anymore and the relay will relax and the pump will not receive voltage anymore from the new wire that I ran from the battery. Make sense? Did to me when I wrote it.

Anyway yesterday I got the used solenoid resistor relay that I bought off EBAY and might install it someday.

Sorry, but I don't know what you meant by *using the relay from the series four*. There ain't one if you discount the Circuit Opening Relay that all cars have. I'm a little vague on that.

 

But wait a moment. If you have a series five, which has the fuel pump resistor relay assy up near the afm, then what you can and evidently want to do, is aquire a relay from radio shack and do as I described above.

Mount it near the jack/antenna area with a bolt or so. Attach a new wire to the relays ground and to a nearby ground/bolt. Use the BLUE wire from the fuel pump plug to power the relay. Just pull the Blue wire out (depin it) and attach it to the relay. You will probably have to splice some extra length to it to reach the new relay. Then run a NEW WIRE from the battery to the NEW RELAY. Put a inline fuse in that wire and locate it near the battery. 15amp will do. Then run another new wire from the output of the NEW RELAY to the fuel pump plug and insert it where the old BLUE wire was. Now you'll have a constant 12plus volts all the time when the car is running. The switch in the afm is still the controlling item it always was. Something like that.

 

My s4 TII has the same fuel pump relay as my s5 N/A. Its a small relay with two wires going to a heat-sink looking thing all attached to a metal plate. In the FSM it shows the s4 n/a as not having one but the TII does. Is this the correct part. Or is there something somewhere else.