Happster26

I have no fuel pressure. Confirmed power all the way to the inertia switch in the trunk. Constant power when key in "on" position, which is odd, because I thought it would only power up for about 6 seconds and then the relay would cut power. Checked the pins at the constant control module in the passenger front wheel well. Constant power from the battery confirmed. Checked continuity between pin taking constant power on the module and the pin sending power to the pump. There was none, suggesting to me either: 1) there is an internal relay in the module that is normally open when there is no power and the module is fine; or 2) or the module is no good? I hear nothing from the tank when I turn the key with everything plugged in, which points to the pump given that I have power. But I wanted to be sure it wasn't the module, because I expected it to cut power after 6 seconds, so it wasn't acting as I suspected. Only have about 40,000 miles on this stock Cobra pump, but I hear they suck and plan to upgrade to the Walbro GT Supercar pump if I need one. Any thoughts?

uberstang1

Chances are its the pump, if you really wanna confirm simply disconnect the harness for the pump near the tank behind the back bumper. Remove the harness pin clip and pull the wires out, ground the ground and put power to the power, if the pump comes on then it could be something else.

cliffyk

The PCM controls the pump via a variable duty cycle signal sent to the fuel pump driver module. A signal of 5 to 50% duty cycle runs the pump at 10 to 100% capacity (though 100% is rarely/never commanded), a 75% duty cycle signal turns the pump off. The FPDM does this by varying the voltage to the pump.

The points you metered would be a constant +12 V with the key on.

Here are the wiring diagrams for the CCRM and the FPDM/pump.

Here is a description of how it works...

Happster26

Thank you both. Tank was rusty and rubber grommet for filler neck was split, so i dropped the tank anyway. Ran power and ground to it and she's dead. Snagged a Walbro 255 and blasted and painted the tank last night. A little undercarriage work and she'll be growling again. Any one know where i might score a fuel filter bracket to make her mint?

Thanks again guys!

uberstang1

The only place your gonna find a good looking fuel filter bracket is if u can find one new, they all look rusty. Just take it somewhere to get powdercoated and be done.

Happster26

Yeah, she's too far gone for that. I'll just have to fab one up.