MatteC6

Sorry guys for bringing up an old thread, but I think I'm facing the same problem with my C6 2008 F55 model, and I've been facing it for a month now. I thought it was a fuel pump issue at the beginning.

So I checked almost every single topic about fuel pump issues in this forum. And I found out this one is very similar to mine.

I checked out the fuel pump relay under the hood, it looked fine and tried to swap it with different similar relays but that didn't fix the problem. Until I went through this thread and tried to touch/move the fat grey wire (fuel pump power) from the fuse block to a bulk head just behind the battery and the engine fired up immediately.

I'm just wondering now, shall I replace the stock fuel pump wiring harness with Racetronix? Since the fuel pump and the relay seems to be working fine.

Thank you in advance

sevinn

I think you should do what I did and check the connector in the junction block. If it looks corroded or burnt just splice around it and make a weather proof connection. The racetronix harness will take all of the load off of that connection and make the original setups purpose signal only. I think the $50 it cost was great peace of mind.

Racetronix

MatteC6

Thank you! I really appreciate your reply. I'll remove the battery and inspect the connector condition tonight.

armerjr

I'm having the same problem. I don't see a gray wire on the connectors on the bulkhead. Do you have a pic or can part diagram? Thanks for the help.

sevinn

I'm sorry I never took any photos. I will see if I can pull up a diagram. If it helps, it should be one of the fattest wires in the connector.

OregonMike

Bumping a 4 year old thread because I just had to have my 05 towed home Tuesday. Our first 100 degree day of the year and I'm dicking with the stupid car trying to get it to go. Was a bit frustrating.

Anyway, before calling for the tow I did all my standard c6 no-start things to no avail. Disco'd negative batt. Swapped relays, still no start This is all crank but no start btw. Battery/fob/clutch switch etc. all good.
.
Got her home and learned a thing about window indexing (I've got the top indexing down pat, only done that 100 times) but I had the driver's window down when I disconnected the battery. The driver's side would NOT go up. I could hear a relay or something in the door but no up, no down. Turns out that there's a down re-index too. Held the switch down for ~10 seconds and all of a sudden it started working again. I did re-index at the top after. Wish I would have thought of that last night...before it rained

I also recalled reading about running out of fuel at 1/2 tank. I was right near a 1/2 tank so added 2 gallons and still no start.

Anyway, I'm done messing with it tonight. I'll try to find this gray wire tomorrow and see what I figure out. I know I'm getting signal to the relay. I jumped the relay pins and heard the pump come on for a second. It put enough fuel in the rails to fire up. Quite sure I'll find a flaky/burned wire at the firewall. No burn marks on the relay either. It's not the over-current that smokes relays problem I don't think.

sevinn

Hope you get it figured out! A racetronix hot wire harness should be on every c6 as far as I'm concerned.

C5 Diag

I did a fuel pump relay circuit YouTube video a while back on my 2001....your relay configuration will be the same except for possibly the ground locations...if jumping pins 87 and 30 got the pump running your issue is on the control side of the circuit...you'll just need a 12 volt test light...for checking the ground circuit I use an old headlight bulb and see if the ground side can carry the current...pump draws about 5-6 amps...hope it helps !!

tabbruzz

great video.....using it now to find mu issues

C5 Diag

Thanks about the Vid...it says in your profile you have a '99 but this is posted in the C6 tech it looks like...if it is indeed a '99 I will move your thread over to the C5 Tech section....if you have any questions about the test I can PM you my Cell # !!

tabbruzz

If you can PM me your cell I would greatly appreciate it...Tony