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1999 F250 7.3L won't start. Turn ignition on connect AE and carry out buzz test, either no buzzing at all on all 8 injectors or intermittent buzz when testing all 8 and either no buzz or very slight buzz in individual injectors.
If I leave the ignition on for approx. 5 minutes and then carry out a buzz test, the buzz test passes and the truck will start.
What could be causing this? is there a sensor or something that has failed that is pulling the voltage down initially preventing the injectors to fire?
No obvious chafing. New UVCH, injectors and glow plugs have been installed.
Putting a multi-meter across the battery shows 12.3V, on AE the battery voltage is showing 11.4V. After the ignition has been on for 5-10 miutes the AE shows a battery voltage of 11.7 - 11.9V
^^^Agree with Wes. 12.3V is low, even after a glow plug cycle. Your batteries, cables and grounds, alternator might need some attention.
How old are the batteries?
Battery cables in good shape? - check/clean both ends of each cable.
What is the voltage at the batteries at idle after 2 minutes (after glow plugs are off)? 13.8-14.4V would be a good range.
On Friday morning tried to start, just turned over. So turned ignition on and left it on , was sat in truck and heard a click (relay etc) from behind the dash after 5 minutes of the key being on. Turned key off, back on and started immediately, took for a drive to town - truck is running awesome with the new injectors etc lots more power than before. Had to go to a few stores in town, wondered if i would have to wait 5 minutes to restart the truck each time. Went to multiple stores varying in times leaving the truck anywhere between 10 to 30mins and every time started 1st turn of the key and ran perfectly with no misfires etc.
What would be making the clicking sound behind the dash after 5 minutes and only affect cold starting due to not firing injectors (buzz test always fails up until this point)?
Do you get a WTS light when you first try to cold start the rig? Trying to see if the PCM is getting power and alive during this event.
The relays in the central junction box include the fuel pump relay - that one might be tired and clicking late, on the first start of the day.
Any white smoke during cranking when you try to cold start? Can you hear the fuel pump cycle for 20 seconds when you turn the key on cold? If no smoke, or no fuel pump sound, it could be that the fuel pump is not energizing.
You can pull the radio and check this relay. I think 99-01 have the fuel pump relay in the central junction box.
Do you have any codes? I would think there'd be something captured during that crank no start period.
I would see if you can identify the relay that is clicking after 5 minutes on that first start. Maybe pull the radio out or ash tray, and the cover to the central junction box, and also pull the dash knee panel and fuse box cover, so that you can put your hands on each set of relays, and feel which one clicks after 5 minutes. That sounds like a long shot as I write that out.
Could try logging FIPW during that first crank of the day, to see if the IDM and PCM are in sync - 0.6ms PW. Throw in the other useful PIDs while you are at it: ICP, ICP DC, RPM, and whatever AE monitors for battery voltage.
Well, the trucks been sat there a while - been too busy to get some time on it, up until last week.
With batteries fully charged, meter was only reading between 11.4 & 11.7 Volts.
Removed front DS fender to gain access to IDM, carried out all the tests to check from IDM connector to injectors, all 8 injectors reading 3.3ohms.
Checked 12V supply to IDM with IDM unplugged - good (noticed battery voltage was now up at 12.8Volts.
Pried off the cover for the IDM, found the bottom RHS where the power goes in on the main connector to be rusty and was sat about 1" of anodized aluminum powder. Cleaned out the IDM with electrical contact cleaner.
Now absolutely no output from the IDM when trying to carry out buzz test.
Installed new IDM - truck starts 1st crank even when cold (and we are at -20'C at the moment).
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