arghx

iTrader: (3)

88 Turbo II. Fuel pump was rewired by a previous owner.

I am trying to see how much voltage is getting to my fuel pump (Supra TT pump), even after the rewire, because I plan on a 400rwhp setup and I just want to keep an eye on it. I actually am running a voltage gauge in one of those gauge panels by the radio that were sold a while back.

I checked the wiring diagram in the FSM from the FAQ and it appeared to indicate the blue wire going into the pump. So I stripped back the blue wire and metered it and it appeared to have voltage (it was a couple weeks ago so I don't remember the details anymore) with the fuel pump check connector jumpered. I start the car and my voltage gauge is just pegged at max (18v) which can't be right.

What would be the proper way to hook this up?

dean23

wow... i was about to suggest the blue wire myself, but then the 18v comment threw me off... have you checked the wire with a voltmeter or a multimeter? the votage gauge itself may not be calibrated correctly.

and what alt. are you using? correct if im wrong but a stock alt. shoudnt be pushing much passed 14v through all the wiring. i know the TT pumps have been known to really suck some power, but i wouldnt think that would cause it to raise the voltage.

NZConvertible

That's the right wire but I don't see how you could get 18V on it. What's the battery voltage?

BTW, back-probing the the connector is an easier and safer way of measuring voltage on a wire. You should measure voltage across the blue and black wires on the 4-pin fuel pump connector.

arghx

iTrader: (3)

well the battery reads in the normal voltage range (like 13.7, 14) with the car running. The reason why I had planned to have it hooked up like that to a gauge was so that I could just eyeball it while I'm boosting, so backprobing a connector is not too useful there. It's gotta be something messed up with my wiring or just the autometer gauge is somehow sensitive, poorly scaled, or otherwise weird.

The gauge has power, ground, and a sensor wire. I have power tapped off the switched +12V behind the radio, just like my other two gauges. The ground might also be tapped off the radio ground. Then the sensor wire just runs through the car under the carpet to the blue wire on the fuel pump. The connection is fully insulated. Could the ground I am using somehow mess this up?

RETed

It's supposed to be the two thick wires for power and ground.
IIRC, the actually power wire is blue, but it turns black after the connector?


-Ted

NZConvertible

Been there, done that. I assume this is only for diagnostic purposes and not something permanent. I used speaker wire to extend the wires on my DMM to allow my to monitor fuel pump voltage while driving. One end of the speaker wire was terminated with male spade terminals that slipped into the back of the fuel pump connector. The wire was run through to the passenger's seat and the other end of the speaker wire was wrapped around the two DMM probes and taped up. This served for before-and-after testing for the fuel pump rewire.

Ah, Autometer... Forget that, use a proper DMM instead.

Nope, ground is ground. A bad ground connection would show reduced or no voltage.

NZConvertible

Yep, it is.

From memory both wires attached to the fuel pump plate itself are black. I think. Anyway, the colour-coding only applies on the harness side of the connector.