3.8 LS Fuel pump test

2000 LS 3.8 failure to start. Starts with starting fluid sprayed into the intake. No fuel pressure - Fuel pump does not run when key is turned on. Fuses good, swapped relays. Have not checked resistor yet. What lead of which of the 2 plugs (4 wire or 3 wire) on the fuel pump should I apply 12V to in order to spin up the pump (wire colors)? My Logic: If the pump pressures up when direct voltage is applied, my problem is in the relay circuit, if the pump will not spin up, the problem is the pump if the pump spins up but still no pressure the fuel filter is plugged (not likely since the pump is not currently powering up). Thank you.

Have not checked resistor yet.

Welcome to AF.

The fuel pump resistor is only applicable to the L67 powered GS or GSE models not N/A L36 LS models.

There is a fuel pump test connector located under the main engine compartment fuse box.

Also, the gray wire at the fuel pump assembly connector rings a bell and has the 12 volts from the fuel pump relay. Use black wire for ground.

Thank you. How is the "fuel pump test connector" used? update this PM 4-8-10: Didn't find the test connector. No 12V at the gray wire on the 4 pin connector, when disconnected or connected, with the key on or off. 5V on the 3 pin connector gray wire with (black?) stripe with the key off. My logic didn't work, pump doesn't pump with 4 pin plug disconnected and 12V applied to where the gray wire connects to. Or with black pin grounded and 12V applied to gray pin.

You may have more than one issue. A bad fuel pump and wiring and/or something with the fuel pump relay not energizing.

The test connector should be there if you look carefully for it. It is normally tucked up with that wiring harness that runs in to the cabin from under the fuse box. Just apply 12 volts and a ground at the two contacts. You can do this with ignition to off. Also, be sure to fuse the hot lead used with a similar rated fuse.

Thank you for the insight. Was the fuel pump. Had it towed to the dealer. $833 later I have a plastic and crap souvenir that cost as much as a decent 42inch flatscreen TV. So much for modern technology. My old truck fuel pump can be replaced in a half hour and for $25 bucks.