This is cross posted in the C6z forum as well....

Car is a 2008 Z.

Ok, so I've now gone through two, or was it three fuel pump relays?

I've also had issues starting when the car was hot for quite some time.

This morning it was really weird, the car wanted to start, but would crank a few times and just stop. No codes (CPS), no limp mode, no cranking for 15 seconds.

I had the car towed home, and by then it had cooled off some. When I tried to start it, it would crank for a longer period of time, like it did the last time the fuel pump relay failed. I swapped it out with the windshield washer relay and it started right up. Ran a bit rough for a bit but eventually settled down and idles fine.


Questions:

How can I test the fuel pump, to see if its going bad? Where is the ground for it? I have a multimeter to test, just don't know what to look for.

Second, how can I check/test the fuse panel in the engine bay to ensure the connectors and the board underneath are good?

I'm so sick of dealing with this I'm almost ready to give up...

Thanks in advance!

 

I dealt with a very similar issue on my 2005 that ended up being a bad connection at the junction block behind the battery (would be near your dry sump tank). I'll dig up my old post about it when I get to a computer. Hopefully it will help!

 

I will go with bad connection for $100 as well.

But you might start off by checking the engine fuse block for problems there.


Granted that the fuse block is a PITA to separate once you pull it from the lower block section, but most of the time its the terminal clip that the relay clips into that is either heat bent open, or corrosion the problem (both are fixable, so you don't have to buy a new fuse block to solve the problem).

https://www.corvetteforum.com/forums...post1582973586

 

Thanks for the suggestions so far!

Anyone else have any other advice?

 

Also check the grounds. GM bought my C6 back because of issues with the ground straps.

 

I'm sorry I forgot to update this with direct links to what happened to me:

Not much info here, but maybe some of my troubleshooting will help: https://www.corvetteforum.com/forums...post1577214205

More info here and some other good info by some other members: https://www.corvetteforum.com/forums...post1576787286

I wish you the best of luck in getting this fixed!

 

I Got into the wheel well last night in an attempt to Ohm out the fuel pump harness.

I got the connector undone, and probed the connector thats fixed to the inner wheel well. Battery was disconnected, fuel pump relay pulled. I grounded to the bolt/chassis that's visible right there at the filler neck. . I got continuity on all 4 pins. ???

I also attempted to OHM out the other loose end of the cable/connector and got no continuity.

Does that sound right, or did I have it backwards?

after that, I was poking around the fuse box in the engine bay, I got the upper fuse panel disconnected from the bottom part, but it had a small bundle of red wires (5 or so) still connected. I stopped there and put it back together due to lack of time. Is there an easy way to get those wires disconnected? They looked as if they went inside the lower fuse panel.

Once that's disconnected, do I loosed the silver posts/bolts from teh top to separate the upper and lower fuse panel?

Thanks in advance!

 

Scroll down to a thread by theVcar entitled inspect fuse panel underside (help) and you will find details on taking the fuse box apart.

 

Well, after much trial and error, hand wringing, headaches, a tow truck and alot of input and other stuff, I think I got it figured out.

Using the links suggested above, I took the relay/fuse panel in the engine bay out:




I have to be honest, "unswaging" those bolts/standoffs so I could separate the panel was a major PITA! It took way more time than it should have. After some prodigious swearing I got it all apart:




Guess what I found? Two burned wires, and not the ones that feed the fuel pump relay that has burned out twice in last 2.5 years. The two wires that burned are underneath the fp relay, so my assumption is that they are somehow related. Anyway, using the writeup in the headlight thread link above, I replaced the two wires with a few cents worth of wire.






Ive heated the car up twice now, and brought it back home hot. Shut it off and repeatedly started it up over and over, like 10-15 times, and not once did it slow crank. I will say that when hot, I have to blip the throttle a little to get it to start, but that could be the tune, or the ls9 injectors I've got; I'll know for sure once I address that issue, but at least it doesn't seem to slow crank anymore to the point where it goes into limp mode. Time will ultimately tell if I cured the issue once and for all , but things are looking up!

Thanks to those that posted those links!

 

Can you trace back the harness connector pin numbers of the burned wires? It would be interesting to know which circuit they are part of.

If fusebox wires are melting from excess current before the fuse blows, that's another defect on top of the existing fatigue crack problem with the low-beam circuit. GM really needs to rework this part.

 

If I remember correctly, it was F5 and F6. Like I said, no relay there so it was internal to the circuitry.

 

I also need to add that the wires were not completely burned, but the corrosion/burn was enough to cause problems (slow crank) when heat soaked.

 

Excellent find TreadHead!

 

Definitely couldnt/wouldnt have been able to do it without the wealth of info from this forum and the members. Outstanding! Bravo!