Vx LS hard to start

[gen5]

Hi thanks for the add.i have vs LS v8 hard to start on the 1st start key off then on it starts I've spent hours on it as iam a motor mechanic. I've had security turn off different pcm what I've found is intermittent injection on 1st start is the problem no codes cam /crank coralation ok checked with scope all powers and earth checked it's driving me crazy any help would be appreciated thanks in advance

 

[lmoengnr]

Hi thanks for the add.i have vs LS v8 hard to start on the 1st start key off then on it starts I've spent hours on it as iam a motor mechanic. I've had security turn off different pcm what I've found is intermittent injection on 1st start is the problem no codes cam /crank coralation ok checked with scope all powers and earth checked it's driving me crazy any help would be appreciated thanks in advance

Slightly lazy fuel system?

 

[gen5]

Slightly lazy fuel system?

Checked fuel pressure when it's playing up it's ok

 

[Jezza]

Have you replaced the cam sensor at all recently?

I had a weird starting issue that ended up being a faulty aftermarket cam sensor that caused issues on initial start but then fired up on 2nd start. Replaced it with a genuine GM sensor and that fixed it.

 

[Forcedvp]

Try full throttle on first start next time. Just to see if its a possible leaky injector issue or tps

 

[gen5]

Have you replaced the cam sensor at all recently?

I had a weird starting issue that ended up being a faulty aftermarket cam sensor that caused issues on initial start but then fired up on 2nd start. Replaced it with a genuine GM sensor and that fixed it.

Hi jezza yes it just had 1 replaced as it had a cam sensor code before iam not doing the work on it it's at work place so not sure how it was starting before but came it with a hot starting problems thanks for feed back think I get a gm 1 and replace it

 

[st3r3otyp3]

Hi, I've got this exact problem, is the OP still around, I'm guessing he might of fixed it.

 

[lout]

faulty check valve in fuel pump?

try turning to reds for 5 seconds
then turn off
then attempt to start
try following this for a week as a diagnosis trial

 

[st3r3otyp3]

faulty check valve in fuel pump?

try turning to reds for 5 seconds
then turn off
then attempt to start
try following this for a week as a diagnosis trial

Hi, question on that would be it's passed a pressure test, if it was faulty would it still pass?

Just have to add sometimes it will start first go hot or cold.

 

[lout]

will still pass a pressure test
if you were to connect your pressure gauge and leave it connected
it should hold pressure for a week or so
you will probably find yours drops over 5-10 hours
so when you go to start in the morning there is no fuel pressure
until pump has run for a few seconds
check valve can be intermittent
same deal as you, i am mechanic/auto elec and had this on my wifes car
took months to diagnose as also had to translate from wife speak to technical speak