Compression Ignition Addict
Join Date: Dec 2007
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So sure, let's start with the basics -
My usual No Start -
WTS Light? - do you get it when you first roll-on the key? (shows the computer is running)
Do you have a spare CPS to try?
Is there fuel in the fuel bowl now? Does it refill after cranking? (open the drain lever to check) Look above the pass ft tire, you'll see a 3/8" metal tube, against the motor that ends there, it's the drain for the bowl (yellow lever you slide to the side). Get a cup, open the lever, drain the fuel bowl, look at the fuel, close the lever. Then, turn the key to the ON position (should hear the pump) for 15 secs. Drain the fuel bowl again, whaddya got?
Can you hear/feel the pump running (below the dr seat, against the framerail)
Could the fuel gauge be giving a bad reading? (Below 1/4 tank?)
Is it cranking fast enough? - it won't even TRY to start if cranking too slowly.
Is your truck "chipped"? If so, remove it as a Test.
You can unplug the ICP sensor, as a Test, so the PCM sets a default value for the IPR to run on (expect this to set a new "Low ICP" code, don't let that misdirect you after a scan).
Did you check the plug and sheet metal nut going to the IPR? That nut can vibrate off and allow the solenoid going over the valve to slide around. The wires going to the IPR can get brittle, crack, and short together. Make sure the plug & wires look in good shape.
NEXT, think of the PCMs requirements for starting;
1) ICP over @500psi
2) RPM over 100
3) Cranking Voltage above 9v (in an '02 - earlier trucks have higher requirements)
If you can, monitor all this with your tuner while cranking.
Additionally, the IPR% will tell you much about the health of the HiPres Oil system.
Voltage too is going to be very important, if it drops too low the PCM may "drop-out" and not be able to read CPS signal.