I am changing back from Mega Squirt to GM EFI, so I am in the midst of installing an old stock GM TPI harness form an '87 model year onto my 1992 RS. I have a question on the fuel pump wiring.

The harness is from a 87 MAF car and I repinned it for a 90+ MAP car. So I have to change the way the Fuel Pump wires are routed. For the 87, It had the fuel pump relay control(tan) and Fuel Pump Power (brown/white) coming from the C207 connector. The C207 is the clear two row eight column clip. What do those two wires actually do? Specifcally the tan colored one? Were they just a switched 12V or on with key?

My other question is what is the Fuel pump prime connector? What does that do? Is it only for ALDL diagnostics?

 

IIRC, the pump test terminal just activates the pump.

As far as the wiring goes, I'd pull out the schematics on the two cars and compare them before I'd trust what somebody has to post on here. Plus I'm being lazy

Post up again if you can't find the info you need on the wiring, I'm pretty sure I have it buried on my computer somewhere from when I did my MAF/MAP conversion. IIRC, TAN feeds ground to the coil side of the pump relay. Brown/wht I don't recall though...

 

On my '88 harness, both fuel pump wires were on C207 also.

The relay control wire pulls the relay closed when the PCM commands the pump on.

The power wire is the relay output 12VDC feed to the pump.

 

On my 88' the tan/wht wire is connected to the MAF, ECM, Fuel pump relay, fuel pump, and oil perssure switch. The only tan wire on my system is from the fuel pump to the gas tank harness connector, at the harness connector it changes to tan/wht which run up to the engine bay.

The ECM, and Oil pressure switch, switch 12v to the tan/wht wire.

With the key off the fuel pump can be primed by applying 12 volts to the ALDL "G" terminal allowing fuel pressure testing with the key off, you can also use it drain the gas tank.

 

I think that I have figured it out. Trickster e-mailed me his whole manuall for our cars a while ago. So after looking at it for a while, I think I got it figured out.

One other question though is where does the red lead (ALDL test) go into the cabin at? Through the bulkhead connector?

 

The red/blk wire for the fuel Pump test ALDL Terminal "G" goes thru the bulkhead connector and changes to an orange wire connected to the "D" terminal of the Fuel Pump Relay on the firewall above the bulkhead connector.