1997 5.7 Vortec won't start.

[SwampHound]

One of my customers at work told me it might be a crankshaft or camshaft position sensor. Perhaps...

My dads 05 sierra needs a new one. Doesn't cause any problems except every once in a while it will refuse to start. After the tenth try it will fire up.

 

[Big D]

check for spark,

if its got spark, spray some starter fluid down her, if she starts, its most likely a fuel problem.

 

[Tripp]

I sprayed carb cleaner into the throttle body while my girlfriend was cranking it over and pressing the gas pedal. Then I checked all 8 plug wires with an extra spark plug and every single one had good spark.

Still no starting. Shoulduld I go buy the sensors? Lol

 

[Jrgunn5150]

No, check for fuel at the rail, key on

 

[Tripp]

No, check for fuel at the rail, key on

dude, I did that as well. I held the Schrader valve open while she turned the key to the run position and fuel was coming out.

Any input available that's actually helpful?

 

[Jrgunn5150]

Nope,since if you verified spark and verified fuel, it should at least catch and attempt to run..

 

[Aloicious]

just because the schradar valve sprays fuel doesn't mean it's working properly, the spider injectors are pressure sensitive and very picky, if you're not getting enough pressure they just flat out won't open. get a gauge on it and see what you're actually getting. with these spider injectors the difference between a running vehicle and a driveway paperweight can be just a few PSI. grab a gauge and post your numbers for: key on engine off priming peak PSI, how long it holds that peak psi, and cranking psi.

definitely do that before throwing random parts at it. weak fuel pump failures are far far more common cause of no-start issues than sensor failures, especially on these vortec's

also, have you checked for any freeze frames or codes or anything? a sensor failure should throw a code. a fuel pump failure shouldn't.

 

[BOTTLEDZ28]

Does your truck have the factory security system? My truck does this from time to time and at first I didnt think it was the VATS since the light didnt come on. I pulled the cluster and found out the previous owner removed the bulb!

 

[Jrgunn5150]

Crank+fuel+spark will result in some kind of action, be it a cough, spit, sputter, backfire.... No matter what your PCM, sensors, VATS is doing

 

[Tripp]

Crank+fuel+spark will result in some kind of action, be it a cough, spit, sputter, backfire.... No matter what your PCM, sensors, VATS is doing

Exactly which is why I feel it's the CKP sensor, cause I was spraying carb cleaner down the throttle body and it still wasn't starting. It does cough to try to start when you're cranking it...