Cranks strong but won't always start first time, always on second.

[dwprog]

My '05 Avalanche has started great every single time since I bought it about 6 months ago. I recently had all the brake lines replaced, maybe 2 months ago. Ever since then it would not start on the first try probably 1 of every 2 times, but on the second attempt it always starts and runs fine.
I tried priming the fuel pump by turning on the ignition, waiting for 5 seconds, turn off, then back on, etc, and I still get that problem. I rented a fuel pressure gage and it holds the pressure fine, upon ignition the fuel pressure jumps to around 46-48psi immediately. I turn it off and fuel pressure stays put. When the truck starts normal it stays at 50psi. When the truck struggles to start the first time while cranking the fuel pressure is at 50psi then too, so I am almost positive it is not a fuel pump or pressure regulator issue. Sometimes if the truck sits overnight it starts up perfectly and sometimes 2 minutes after shutting it off it struggles to start, so there is no definitive pattern here.
One thing that happened I would like to add is on the drive home from getting the brake lines replaced (and when I first noticed the starting issue) my check engine light went on. I checked it and it read camshaft position sensor. I replaced that and check engine light has not come back on, but I still have the starting issue. I had the mechanic hook up his fancy code scanner to look for any history of weird codes or anything, but he saw nothing unusual. He thought maybe relearning the crankshaft sensor may help (I know it's not the camshaft sensor that I replaced but there wasn't a relearn procedure for it) but that did not help either.

I am at a loss and it is driving me nuts. Could it be something electrical? Could it be a loose ground somewhere from the brake lines being replaced?

Any ideas

Thanks

 

[jimanth]

Had the same issue, engine code, replaced Camshaft position sensor with Duralast from autozone, and keep having start on second try problem.. Took it back to autozone, got another and still start on second try problem, but engine light came back, camshaft high voltage. Bought ACDelco sensor and has been fixed since.

 

[dwprog]

Had the same issue, engine code, replaced Camshaft position sensor with Duralast from autozone, and keep having start on second try problem.. Took it back to autozone, got another and still start on second try problem, but engine light came back, camshaft high voltage. Bought ACDelco sensor and has been fixed since.

Awesome thanks. I just ordered the AC Delco part. Hopefully that’s it.