My 2003 F-350 SD Crew Cab ran fine the day before, but the alternator quit again (fouth one the rotor wire pulled off) then it would not start in the morning. Turned over fine after charging the battery overnight, but no start. No smoke out of the exhaust when trying. I disconnected the ICP and still nothing, checked the glow plugs and controller and they were fine, but did not suspect that as there was no smoke, no fuel. I unplugged the ICP and still no start. Checked the fuel pressure KOEO and starting and it was just over 60 psi. Checked the FICM (7 screw) voltage, and it was 12.4 for a few seconds, then 48 KOEO during the buzz test and after. During cranking it started at 48 then after a few seconds of cranking dropped to 12.4. I removed it and resoldered the resistors as outlined in the tech folder for the four screw, but did not do the small flat resistors as they are different and I was unsure. Assembled the FICM and retested it, same scenerio exept the voltage is now 15.8. I am assuming that when the HPOP builds pressure when cranking and the ICP sees 500 psi, the injectors are powered and that is what is causing the low voltage. I must have not soldered well enough to repair the crack, but the solder looked to have flowed to the PC board. I will try soldering again unless there is something I have missed.

 

Are your batteries good? Bad alternators can ruin them. Sure sounds like the FICM is still an issue.

 

Yes, both batteries replaced a year ago and load test perfect, 500 amp draw, 10.6 volts

 

ok Im gonna say that a 750cc battery should be a little more then 500 amp and a little more then 10.6v.
You seem to be on the right track to fixing the issue.

 

I believe the spec is the CCA capacity X 50% the voltage should not be below 9.6 volts checking each battery seperatly. One battery at 500 amps was 10.6, the other at 10.75, that should give me 1000 amps at 10.5 volts, Cranking voltage is 12.4, more than enough to start it. I even boosted it off my tractor to no avail.

If the FICM voltage starts off at 48 volts at the initial cranking, then drops lower after a few seconds of cranking, is it possible it is turning off the injectors because of anothe problem? I have checked fuel presure and unplugged ICP and it still does not start.

 

if ficm voltage is droping below 45v durring cranking then either oyu have a supply issue or a dc/dc converter failed.

we can discuss what you think is a good battery. Just so you know the pcm will tend to want to reset at 9.6v.

 

Well, I sent my FICM to Swamps to get repaired and modified for higher voltage. It is still in the mail on the return trip, but I tried a freinds FICM that was replaced because his voltage was 28v. I hadn't charged the batteries for a few weeks, and had been checking fuel pressure and HPOP pressure and the voltages twice after resoldering. Installed his and it was hard to start and it smoked black for the firstminute or two, but once it warmed up a bit it ran fine. I am really glad with all of the comentors help, we found the problem, thanks to all. Now I am installing fuel and HPOP pressure gauges under the dash. I am also looking for an analog voltmeter as well