RelayThisSensorThat

Edit: Title Should Be Heat-"RELATED", oops
Good day, those far more knowledgeable than I.

My 2000 Camaro Z28 has had an intermittent start issue for the five years I've had it. I'm starting to suspect there are multiple factors at play disguising the real issue(s).

Current Situation: Will crank all day, no fire 9-out-of-10 of time.

Past Fixes That Seemed to Work: Replaced fuel pump relay, replaced starter relay. Seems like this problem only emerges once seasonal weather starts to warm up, so maybe these fixes just coincided with cooler weather.

Observations/Data: Will occasionally start after repeat attempts / airing cabin & engine bay per someone's theory that it's heat-related electrical issue, but that may be random coincidence. Battery is charged, fuel pump powers w/ key at 'On' position, Security light goes off so key resistor probably works. SES light is always on: I've had codes thrown from a knock and O2 sensor; O2 seems to have gone away, but dealer wants to replace knock sensor (read as code P0327).

I don't drive it much, especially not during winter, so there is a possibility of gas getting quite old.

Few days ago, the last time I got it running, was after airing it out. Took it to get gas, turned it off & filled up; wouldn't start. Opened hood & 30 minutes later it started. Drove home fine and so I sat in driveway wondering if I should keep it out for a while when it stalled. Since then, I haven't got it started. But as I said, I'm worried adding new gas may have stirred up some precipitate or something & that may have caused the stall, adding a layer of confusion.

Any thoughts?

Thanks a lot!

TooLateVTEC

iTrader: (2)

I would go to the parts store and buy a fuel pressure gauge to hook to the fuel rail and check the pressure. That will narrow one possibilty down...I think they're like $30.

When it turns over, does the starter sound strong?

RelayThisSensorThat

Starter sounds good and I can crank it as much as I want, it just wont fire.

I'll see if I can find a friend with a fuel pressure gauge; until then, any more ideas?

Thanks for the response.

BaddBird

iTrader: (6)

You need to check rpm signal from the crank pos with a scan tool the next time it wont start.

RelayThisSensorThat

Tried unsuccessfully to start this morning, but outside temp dipped back into 60's *F here, and this evening guess what... it started... but again, that was after i took out fuel pump, starter & ignition relays to examine the box terminals for corrosion to cross that off my list (all clean, by the way)... so again, was it a fluke, temperature or something to do w/ "the general area of the relay box"

Edit:
Update:
After running for half hour, turned it off and attempted to restart. No crank. I had swapped the Starter relay (known good as replaced) and the IGN relay when i was checking the box, and the no crank is exactly what happened before i replaced the Starter relay. I tried again and then it started. So I'm thinking the relay that was formerly in the IGN relay spot might be intermittently bad depending on weather?

RelayThisSensorThat

Just an Update for those interested:
After replacing the IGN relay, the car has started reliably for the past week. Seems to have fixed it.

z28241

iTrader: (13)

Good news!

TooLateVTEC

iTrader: (2)

Good deal, im glad you got it fixed.

Its wierd sometimes how it seems weather will cause cars to do strange things.