2001 8 cyl 4.8 4WD ignition issue.

[Dank1979]

90% of the time, the truck starts fine. The other 10% the truck cranks but will not start. If I wait for 10 minutes, it starts right up, any less, and I have to start my 10 minute wait again. New starter, New fuel pump, new fuel filter, new fuel pressure regulator and new spark plugs and wires. What else could be happening?

Thanks,

[MT-2500]

Is the problem hot or cold start?

Ac-delco/Delphi pump or one of them junk airtes wonder if they are going to work pumps?

Ac-Delco plugs and tune up parts?

Any codes or check engine lights?
Does the security light come oin and go off with key on or stay on when it no starts?

Hard to start hot or cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 55-66 fuel pressure.
Cold start should be 55/62 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 55/62 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
If pressure does not come up with return line pinched or blocked off.
Go to fuel filter and hook a gauge direct to a line at fuel filter.
Pressure should come up to 75 or more and will hold after fuel pump is turned off.
If it leaks down there after fuel pump is turned off it is LEAKING BACK THREW PUMP CHECK VALVE OR PUMP MODULE LINES.
Post back your fuel pressure readings.
MT

[Dank1979]

Happens on hot or cold starts - crap shoot. Pump is discount, learned my lesson here. Plugs are bosch platinums. It's not the security, had a new BCM module put in 18 months ago. Don't have a pressure gage at the present time, i'll have to go get one. Thanks for the advise, will post back when I have more info...

[MT-2500]

Pitch the bosch platinums plug in the trsh can and get a good set of AC-Delco plugs that the good ac plug book calls for.

Most discouunt or airtex fuel pumps are junk and do not have the proper fuel pressure to start or run it right.
Only use ac-delco/delphi fuel pumps.
When no start check fuel pressure and for good hot spark to spark plugs.
Does the security light come on key on and go off or stay on when no start?\
Also check fuel pressure regulator for gas in vacuum hose.

[Dank1979]

No on the security light. At the risk of sounding stupid, how do I check for gas in the vacuum hose? Will it be obvious?

[MT-2500]

Does security gight stay on or go off?
On the vacuum line pull it off of reg.and check for gas in line.
We need the fuel pressure readings?
Pitch the bosch plugs and get some good AC-delco plugs.