No fuel pressure 2000 v6

[utmustang88]

Hi there first time poster but long time reader,
I have a 2000 V6 5spd and the car ran fine(always seemed to have long starts though since new) and now has 40,000 miles on the ticker. over the winter while the LS was in storage the battery died and i replaced it just last week only to find out the car won't start. The car cranks fine and the PATS system deactivates when the key fob is pressed.

When the key is in the key on engine off position there is no fuel pressure up by the valve. I took the rear seat off and listened to the fuel pump and all i heard was a faint bubbling noise and then it shut off;like when you put an empty pop can under water and it starts to fill. isn't there supposed to be a buzzing noise for 3 secs while the pump primes itself? I just replaced the fuel filter and it seemed to have flow through it. how to tell if the fuel pump is bad? there is voltage going to the fuel pump motor input 12.4v and output 0.05 to the two connectors. the relays are clicking. anyone know about the rear electronic module(REM) and the fuel pump driver motor FPDM on these returnless fuel systems? your advice would be helpful. thank you

[shorod]

The Remote Anti-theft Personality (RAP) module is different from the PATS system. The PATS system is deactivated passively by the RF transponder in the head of the key, not by the remote entry key fob. Typically the PATS system will prevent the starter from engaging, so if the starter is engaging but the car won't start, the PATS system is probably working properly.

When you mention you had 12.4V to the fuel pump "input" and 0.05V to the "output," how did you measure that? It sounds like you are considering the "output" the ground for the fuel pump. What you really want to do is check for voltage during the first 3 seconds of turning the key on. If your meter has a "max" feature this might be a good time to use it if you don't have a second person available. Make sure the fuel pump inertia switch is closed and backprobe the positive (input?) for the fuel pump with the red meter lead. Use the black lead to backprobe the ground lead (output?) at the pump and turn the key on. You should see your 12.4V across the fuel pump. You will want to try this with the electrical connector to the pump connected (closed circuit) and with the connector unplugged (open circuit) and compare the results. You'll need to wait a couple of minutes between checks to make sure the system attempts to prime each time. You want to do this as close to the fuel pump as possible to determine if there is a wiring fault or just a pump failure.

If you have good voltage both times at the fuel pump, and you verify that there is no fuel pressure being provided by the pump, it sounds like you have a faulty fuel pump.

-Rod

[utmustang88]

thank you for your input, i wish these cars had a mechanical fuel pump cause it would be a whole lot easier to find the problem and fix, lol, i'm not an a wiz with the electrical. .. the "output" is not a true ground on these system, it actually has voltage going through it and grounds out somewhere else i think over by the fuel door release switch.


ill give it a try and get back to the boards. thank you

[shorod]

Originally Posted by utmustang88

.. the "output" is not a true ground on these system, it actually has voltage going through it and grounds out somewhere else i think over by the fuel door release switch.

Well, that's technically how a ground works, the current flowing into the circuit will flow out as well (minus what's used to produce heat, sparks, etc.).

The return path (aka ground) is provided through pin 12 (black/red wire), connector 420d of the Rear Electronic Module (REM) which is located on the right hand side of the trunk. The supply to the fuel pump motor is pin 11 (green/orange wire) of the same connector.

There is a fuel pump relay that provides power to the REM via pin 1 (green/red wire) of connector 420d. The switched side of this relay receives power from a 15A fuse in the battery junction box. The fuel pump relay is located under the carpet of the trunk liner.

Good luck!

-Rod

[Quik_LS]

maybe a silly thought - but have you checked the fuel cut-off safety switch?

they can trip for the silliest reasons.....

iit's in the driver's footwell.