autoxer6

Looking for advice on next steps.

My stock 2004 Z06 with 35,000 miles stalled while going down the highway. The engine simply cut out, no sputtering etc. There is no fuel pressure at the fuel rail Schrader connection. The fuse and relay are good. Battery voltage is coming out from the relay, and I swapped it with another relay, no change. I found a tan wire at the wiring harness on the right of the transmission that appears to be the fuel pump power. It gets battery voltage (12.2 V) when the relay is on (for two seconds after the key is switched on). I can hear a clunk in the left fuel tank when the key is switched on and off, but no pressure at all.

Two weeks ago, I got a P2066 H C code for the right fuel level error and the gas gage went to zero. It has been at zero since. I calculated that there was about 3 gallons in the tank when it died but I have no way to calculate. I added 3 more gallons to be sure, but I still get no pressure. It should have 5-6 gallons in it now.

I cleaned 5 grounds, including the fuel pump ground and put a new ring terminal on it. I also tapped the left fuel tank with a mallet while cycling the ignition in case it was a stuck pump, no luck.

Are there other things that I can check to determine if it really is a bad pump?
Is the tan wire the power line to the pump? On the schematics I saw posted, they use a grey wire. My grey wire gets a 5-6 V continuously.
It doesn’t look like I can get to the wires on the top of the tank. Is there an easy way to get to them without dropping the tank?

Thanks for the help!
Chris Shay

lucky131969

You really don't know if the pump is receiving 12 volts, because you cannot get to the pump connector. I've never worked on an FFS system, but I see no tan wire in the schematic. The only way to be sure, is check the continuity between the plug(tan wire) and the fuel pump relay socket. That will verify you have the correct wire. The colors in the pump harness should be : Dark blue, Grey, black(2each).

rboineau

I apologize for my ignorance of the late '03-'04 fuel system (I have an early '03 with the "old" system), but is it possible that tank-to-tank transfer is somehow gone sour and one tank, the one the engine is trying to get fuel from, is empty?

autoxer6

Lucky,
I’ll check for continuity between the tan wire and the fuel pump relay outlet. The grey wire seems to be a computer signal since it is a constant 5 v and does not switch with the fuel pump relay.

Rboineau,
My understanding is that the left tank is the one that is filled first and feeds the engine, so even if the transfer pump on the right is bad, I should still have fuel pressure since I put several gallons in the left tank. If this doesn’t sound right, please let me know.

Does anyone have a wiring schematic of the fuel pump for a ’04?

Thanks,
Chris Shay

cdkcorvette7

Image removed... Wrong schematic.

autoxer6

cdkcorvette,
Thanks for posting the schematic. Those colors do not seem to match my car, or a LOT of things are messed up.

Is that for a 2004?

Thanks,
Chris

lucky131969

Yes, the colors I listed are right out of the 2004 manual. The schematic does not look correct.

cdkcorvette7

Not sure of the year, but it matches my 01. I found it in a search while I was troubleshooting a ltft issue (still messing with it actually). I had it saved in my email; sorry it doesn't help you much...

I'm sure one of the real electrical experts here will chime in... EDIT: Actually one already did. I was typing while lucky was responding...

autoxer6

Ok, thanks. I'll look for these:
Dark blue, Grey(2each), black

and I'll check for continuity of the tan wire to the pump relay.

lucky131969

From the 2004 service manual:

lucky131969

I amended my post....sorry for the confusion. I can only go by the schematic, and it shows 2 black wires.....not 2 grey wires( I edited my post). I agree that the 5 volts you are reading, would suggest it's for the sending unit. Sorry I can't speak from more experience with FFS.

autoxer6

Update:
The tan wire in the harness next to the transmission does connect to the ouput of the fuel pump relay. It gets a 12 V signal for 2 seconds when the key is switched on. The Black wire next to the tan wire goes to a ground. 12V was applied to the tan wire and grounded through the black. A "clunk" is heard in the left fuel tank but no fuel pressure.

Are there any other tests that I should run on the pump before I call it dead?

If not, where can I get a pump overnighted at a fair price?

lucky131969

Just curious.....is this a stock fuel system i.e. wiring...no BAP, direct wire, racetronix harness, etc? The only thing left, is the fuel pump connector itself. I guess it's a slight gamble ordering a pump, but you have checked 98% of the wiring. I still don't understand the tan wire v/s grey.....but the meter doesn't lie.

autoxer6

The engine and electronics are 100% stock. I'm not sure about the colors, but like you said, the meter doesn't lie.

Thanks for all your help!

autoxer6

The new left fuel pump is in and the car runs! Here is what was replaced:
Left pump
Right level sender
Clutch Slave cylinder
Clutch Remote Bleeder

Thanks again for everyones help!