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Discussion Starter #1 (Edited)
Tests to run in order to BEGIN diagnosing a no-start:

First - scan and record ALL codes (DTCs). Make sure batteries have been fully charged and individually load tested. Verify critical fuses and relays, especially fuse F2-22 and PCM relay 302 (under dash), FICM relay 304 (under hood), etc). Verify proper oil level (and oil appearance) and that you have sufficient fuel. You may want to even change out the fuel filters so you can inspect them (sometimes you can get bad fuel).

1. Verify injectors are buzzing (KOEO). During the test, all injectors will buzz for 2 seconds. Then each injector will buzz sequentially for 1 second.
2. Verify cam/crank sync and FICM sync when cranking. Both sync values should be "1".
3. Determine system voltage (battery power) while cranking, System voltage should not drop below 10 volts when cranking (10.5 to 11 volts is normal).
"4. Determine rpm when cranking. Rpm must be 150 or above to start. No rpm signal and no SYNC when cranking typically points to the CKP sensor.
If cranking rpm's are low, make sure an accessory (A/C compressor or pulley) isn't seizing up and causing the slow spin."
5. Determine FICM Power (MPower, VPower, LPower). Mpower should NEVER drop below 45 volts (47.5v cranking is normal). Lpower should be above 9 volts when cranking (below 8 v and engine will not start), and Lpower should typically be 11.5 - 12 volts. Vpower should be the same as battery power.
6. Determine Fuel Pulse Width while cranking. If no fuel pulse width signal is received, but rpm, Vpower, and ICP signals are normal, then the CMP sensor is in question. Typical FPW when cranking is 500 μ seconds or greater, up to 2 milli seconds (990 usec low idle and 680 usec high idle)
7. ICP pressure, ICP voltage, and IPR % duty cycle when cranking. ICP pressure should be above 500 psig (preferably 650 minimum); volts should be .9 to 1.2
8. Determine V-reference voltage. Voltage should be between 4.5 and 5 volts.
9. Verify (manual gauge required) fuel pressure is 45 psig minimum
10. Verify that the upper fuel fuel filter fills in several seconds KOEO.
11. If low ICP pressure, verify oil filter housing fills up when cranking (in several seconds when holding the drain valve closed, 10-12 seconds w/ drain valve open)
http://www.nosun.ca/wingnut/051207.PDF
12. Run a fuel bubble test (see detailed instructions). Bubbles from the stand pipe indicate air from the pump. Bubbles from the side indicate an injector problem.
13. Disconnecting various sensors & components one-at-a-time can often times prove valuable (EGR, EBP, ICP, EOT, ECT, BARO, GPCM, MAF)
14. Verify that MAP, BARO, and EBP are within 0.5 psi of each other with KOEO (within 3% of each other)
15. Verify that IAT1, IAT2, TFT, EOT, and ECT temperatures are all relatively close after at least 24 hours with the vehicle off (cold soak).

No Crank
Find the yellow with light blue striped colored wire adjacent to the passenger side battery in the engine compartment, near the vacuum pump that has a "squeeze-and-pull" type connection. Disconnect it, and jump the male end of the connector to the passenger side battery positive terminal. The starter should crank.
A shorted out fan clutch can cause a no-crank. So can a shorted out EBP. A bad transmission range sensor can also cause a no-crank. Try cranking with the EBP disconnected, then the fan clutch disconnected, then try cranking in neutral (in addition to trying to crank in park). Also, don't forget to check the inertia switch (it has a reset button).

Normal 6.0L compression is 400 psig. Anything under 300 psig is a concern. Ignition will be a problem at 260 psig.
 
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Discussion Starter #2 (Edited)
Hopefully I can successfully load some pdf troubleshooting tools.

Attachments not loading. Will get a mod to look into it.
 

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