Hello all,
A new week, a new issue it seems.

I'm afraid I already know what the problem is, just looking for other opinions.

This morning, I started the car up to warm it up for my wife (she is driving it to work this week); get the heater and seat warmers going. The car cranks just fine, purs like a kitten with no abnormalities. She drives it to work today without issue, parks and calls me when she was going to leave saying that the car wouldn't start. I head over there in my truck with a few tools and some jumpers cables thinking (hoping) that maybe something was left on while she was at work; it doesn't seem to be the case.

I pop the hood and have her attempt to start it. The starter turns and turns but the motor never fires up, it sounds like it is cranking strong. I get no messages on the DIC or anything to clue me in. I tested the voltage on the battery and it read just over 12 volts and I know it could still be bad, but I'm thinking it is fine at this point. I then hooked the jumper cables up from my truck and let it charge for a bit and tried to crank it again with the same results.

The fuel pump fuse looks brand new and I believe the relay is fine. I unhooked the battery for about 20 minutes and hooked it back up hoping that it was just some pcm glitch, but that wasn't the case either. Tomorrow I'm going to try to rent a fuel pressure tester to see if I am getting pressure to the rails, but that leads me to the question of how exactly do I know what is normal?

Any advice? Could it just be bad gas or something? Any way to diagnose the fuel pump with the car on the ground? (it is sitting in her office parking lot ).

Sorry for the wall of text and thanks in advance. I've been having a bit of trouble with the car lately. I had to change my RR wheel bearing last week...I was hoping to be able to install my headers and Spinfast92 that have been sitting in a closet for a month now .

 

Wow, you've sure thought of everything. My only thought is the battery. It usually is the problem. How old is it? You said it had over 12 volts but that is not the final test which you mentioned. A load test would confirm it. Jumping it from your truck was a good idea but jumping the C6 doesn't seem to work very often. I've never listened but on some cars you can hear the fuel pump for a second or so before it shuts off. Did you try that?
Good luck and keep us posted. You might post this in the general section for a little more help.

 

Thanks for the suggestion, I may if I don't get too many hits here.

My battery is about 8 months old, but I know age doesn't really mean anything as far as it being good. It's got a 5 year full replacement warranty so I will probably get that checked out first thing. I didn't have time to go get it done tonight after messing with it.

I'll have to try to listen for the fuel pump. Don't really know where I'd stick my head to try and hear it .

Thanks again.

 

Don't forget to check for spark.
Your focus was/is on fuel.

The starter is turning so I don't think it is battery being low. Couldn't hurt to keep it on a charger over night.
Since you jumped...maybe check the other fuses, perhaps security.

Forum luck is with you.

 

What would be the best method to check for proper spark? Used to see if I could get it to arc onto a screwdriver or something, is there any other way now a days? Unfortunately I have to work on it in my wifes' work parkinglot, so facilities are slightly limited.

Thanks for the forum luck. I need it.

 

I would treat it like it was flooded and hold it on the floor before doing anything else. I have personally helped several folks start outfits that were flooded to the point the batteries were run down trying to start them. Nothing to loose. Later! Frank

 

Hi. I purchased a brand new C6 in 2009. I currently only have 3000 miles on it and this past summer I had to get the fuel pump replaced because my car all of a sudden had trouble starting. At first I also thought it was a low battery from not using the car, but that wasn't the case. The car would just jitter a lot and barely start. It would not fire up like normal. Anyways, I would get it checked out to see if it is the fuel pump. That could be the problem.

 

Why don't you start by having it towed home? it's like 100 bucks to tow it home and be able to work on it whenever you want!

Good luck solving the problem btw!

 

If the charging system turns out fine and you got spark & fuel. You might want to run thru all the fuses in the engine bay area. I had a weird problem similar with my z. Long story short, there was a short on a wire going to the injector harness. It grounded out and was popping a random fuse, that was called the emission fuse. I too had check the fuel pump fuse and so forth. Finally when I went fuse by fuse, I was able to find what was popping. Of course my car had a complete motor build, where there was some errors when putting the car back together. Probably a long shot, but thought I would share. Good luck!

 

If you can, put a code reader on it and see what is stored in there.

 

Nice that you are posting it here. You seem to be mechanically savy. I
can say this with certainty i'ts not the battery or charging system in general. I have a Fuel pressure Gauge I made that you can attach to
the shrader port at the end of the fuel rail. It should be 58 PSI at the
port. If you test it and it reads ok then check for voltage at any injector
terminal and ground and look for 12 vdc if not check the fuse for open.
Even if you have the 12 vdc there that does not mean the injectors are firing w pulses. You can also check for primary power for the ignition ckt.
Just to mention a few things to check. If you have no CEL its a little more difficult to troubleshoot without a code reader.

 

Won't be necessary now

I want to thank everyone for the replies, suggestions, and wishes for luck.

Turns out it was the fuel pump relay.

Last night while I was looking at it, it was very dark and I couldn't see everything all that well (I left my flashlight at home). I could just barely make out the diagram on the fuse panel to see which fuse was which and such, so I couldn't see that the relay looked like someone held a lighter to it. The contacts are fine, but it is definitely toast. I swapped it with the fog lamp relay and she started up without a hitch.

What a relief for now, but I know these things don't go for no reason. The AC condenser relay looked a little charred too, I can't imagine how hot one would have to get to burn the other one (I mention it because the two relays are basically touching in the fuse panel). Now to figure out why it popped and the fuse didn't...

Thanks for the compliment! I'm fairly confident in my ability to fix things once I know what is wrong with them, but I still don't know how to diagnose many things as of yet; I have my Dad and the forum here for that one!

 

Cool and congrats on the find.

 

Good news. Your my kind of DIYer. Congratulations.

 

I thought I read somewhere that it won't start when you hold it to the floor? That it's a good way to get the oil pressure up after a filter change?

 

Nice diagnosis by observation. Yes that relay got hot and probably a lousy contact or the Fuel pump may be drawing excessive current. I know you said the contact looked good but were you referring to the
fuse contact or the contacts inside relay # 55 and the plastic body was charred ?

 

I read the same thing somewhere. Haven't tried it.

From a thread (somewhere) about preparing the engine for a first-start after winter storage:

"Put foot on brake and depress gas pedal fully while cranking. Engine will turn over and fill journals etc, but will not start."

 

The prongs on the relay itself looked fine, and the recepticle in the fuse panel looked fine as well, and correct, the #55 relay's plastic body was charred. I will take a pic later and add to the thread.

I'm going to keep an eye on this relay, but so far so good after an hour long commute home today. If the pump is bad I suppose I'll go ahead and swap it with a Z06 pump to future proof for any mods I'll ever want to do .

Thank you guys very much. It's the small victories that count sometimes

 

If you can, would you check the old relay to see if the Coil is burned and
should be open to support the theory that the Coil got hot and burned up
created the heat to discolor the plastic shell then the Coil eventually opened. Then the fuel pump would not turn on and let you there trying to start the Car with no Gas pressure.

I have been thinking for some time to make a diagnostic kit that one can
keep in the car when these things happen. More and more are our Cars
letting us sit. I can think of several senereos when the car wont start or even try to turn over. I will probably put it together and post it up for others to consider for a small price for a few items to make the car testable. What do you think about that idea?

 

That's correct. It's that way to help clear a flooded engine. I actually went out and tried it one time. It won't start. Good thing to keep in mind if someone ever tries to carjack you. (then pull out your carry pistol and cap their a$$)