Ive noticed under load Sometimes(A/C, cooling fan) my fuel pump voltage will drop from 13.5 to 12.5. I think this might be killing my fuel volume when it does this. Anyone know why it does this?

Someone posted a link on the Corvette forum, for Agostino racing, not sure of the spelling. They have a Walbro 255lph pump kit and wireing harness for the C4. These pumps draw more amps from what i read. And can loose up to 20-25% of there rated flow at wot using the stock harness. So they sale a harness for the C4 to boost the voltage running straight to the alternator.

Does anyone know of a plug and play harness for our cars?

 

Don't know of an available kit, but it would be easy to do yourself. You will need a Bosch 30 ampere relay, a 30 ampere in line fuse - both available from any auto parts store, and some 12 gauge stranded wire. Mount the new relay near the stock fuel pump relay, under the hood. Connect one of the new relay coil terminals (terminal 85) to the output of the fuel pump relay (probably blue or tan / white wire). Connect the other new relay coil wire terminal (terminal 86) to ground. Connect the pole terminal (terminal 30) of the new relay to the alternator output, or positive battery terminal through a 30 ampere fuse, using the 12 gauge stranded wire. Connect the the new relay N.O. contact (terminal 87) to the fuel pump, using the 12 gauge wire. Run the wire from the new relay through the fire wall, and connect it near the fuel tank body electrical connector that is located behind the carpet (behind the rear seat back. Cut the fuel pump wire and use the new 12 gauge wire to supply power to the fuel pump. Tape off the stock wire end that used to supply power the the fuel pump.

 

Thanks for explaining that so well Tim....That does sound easy I think even I can handle that. Better idea than buying some over priced harness.

 

The GN guys have been doing this for years with great results. Its a good idea, just like the headlight wiring mod that is exactly like this.