1999 7.3 diesel 150K miles.

Over the winter, it sits in my driveway. I keep it plugged in and start it once a week. Lately when I start it, it cranks over and over several times but will not fire up. I stop cranking, wait a couple of seconds and try again and it will then fire right up. After warming up it everything was fine.

Now that it has warmed up outside, it still requires the cranking, stop and trying again but now even when the engine is hot, I have to do this. Otherwise, runs real good.


Any suggestions on what is going on?

 

Do you have any gauges? Is it tuned? Do you have access to a scan tool?

It could be so many different things......

 

Sounds as though your not building pressure fast enough to fire the Injectors.

echo=on
No Start / Hard Start / Cold / Warm

Tools: OBD-II On-Board Diagnostics, Phase 2 Vehicle Media Communications Unit (Scanner)

1. Select the parameters indicated from the Scan Tool parameter list and monitor while cranking engine.

Data List Monitoring Parameter:
V-PWR 10.5 VDC Minimum.
RPM 100 RPM Minimum (0 - CMP Suspect)
ICP 500 PSI or 3.4 MPAM Minimum
ICPv (KOEO) Spec 0.20v - 0.30v
FUEL PW: 1 MS - 6 MS ( <1 / >6 IDM Suspect)
V-PWR - If indicating a low voltage condition, check battery voltage, charging system or power and ground circuits to the PCM.
DC% - Cranking NTE 20% / 65% is Closed. (IPR Suspect)

2. RPM - Low RPM could be an indication of starting/ charging system problems

3. No RPM indicated with the engine cranking - could be CMP circuit fault, check for DTC’s.

4. ICP - A minimum of 500 PSI (3.4 mPa) is required before the injectors are enabled. No or low oil in the reservoir, system leakage, injector O-Rings, or faulty IPR could cause pressure loss.
Note: If no RPM signal is received, IPR duty cycle will default to 14%

5. FUEL PW - Even though a 1 to 6 mS FUEL PW is shown, it’s possible the IDM did not receive the signal due to a CI or FDCS circuit fault or internal IDM failure.
echo=off

FWIW: Starting the Truck without driving it to OT does nothing for it other than contaminates the oil and drain batteries. Better to just let it sit until you're ready to use it.

 

What Tom means by "not building pressure fast enough" is that our trucks use engine oil, downstream of a high pressure oil pump (HPOP), to fire the injectors. The truck has been sitting, so:

1. How old is the oil? Old, sheared oil won't build/sustain pressure well.
2. What oil is in it? Oil that isn't rated for our trucks is a no-no.
3. Is the oil level above the minimum mark on the dipstick? Low oil levels can cause this issue as well.

There are several things that could cause your issue (fuel pressure, possible glow plug issue), but start with the oil.