L31 don't start

[yukonrrican]

hi. my Yukon GT 97 start to failure during morning driving. I leave at home that t day and in the afternoon don't start. I check sparks and fuel pressure and is OK. During testing try to start but nothing.

What part could be failing?

 

[SunlitComet]

perhaps failed iac starving it of air. does it try better if you open the throttle a bit? but check the pcm fuses under the hood as well. a sensor may be knocked offline.

 

[God]

Fails to start or starts failing?

 

[yukonrrican]

Update..

The engine don't start. I test the crank sensor and is OK (pump and spark activate). But when testing the cam sensor. The 12V supply to the cam sensor is OK, but when testing the cam signal it start reading 0V and then read 9V and never return to 0V. The on/off process never happen.

could be the cam sensor?

 

[SunlitComet]

not really a failed cam sensor will just cause a long hard stall. what are you testing it with. if multi-meter it likely can not respond as fast a an oscilloscope.

---------- Post added at 08:48 AM ---------- Previous post was at 08:47 AM ----------

no dtc hidden in the system?

 

[yukonrrican]

Yes..I'm using a multimeter and turning the engine manually.

 

[SunlitComet]

multimeter not a reliable test method for cm sensor.

 

[yukonrrican]

Any help???

Any suggestion???

the cam and crank sensor has signal. It has fuel pressure and spark.. Any idea will be appreciated.

 

[SunlitComet]

that would leave injectors not firing.
perhaps their fuse?