Batteries Good Still won't Start
 

1999 F250 Super Duty 7.3L Diesel Won't start. Batteries have been checked at shop both pushing over 850amps It will start if someone gives me a jump and it started this morning with the battery charger hooked up and then started on its own a two more times, now it won't start even with charger hooked up. Try's to start but sounds like battery drained but it's not. Any ideas?

Make sure all your connections are clean. If that don't help, have the started tested. Good luck, and welcome aboard!

Take a digital voltmeter and during attempt to start, measure the voltage at one of the batteries..It has to be around 10 volts to start..
Does it turn over but real slow ? Or nothing at all ?
Try shorting out the 2 large lugs on the inside fender starter selonoid with a screwdriver..

I would also use the ohm meter and measure the resistance from positive to positve cable end and to starter and also ground end to ground end just to see if you have a corrosion issue inside the cable. Common problem. I had trouble with what looked like a good clean battery connection but turned out to be oxidized enough to cause problems when cold cranking. Clean the connections really well if resistance checks out.

Starter Passed But....
 

Took starter off and had it tested, and batteries re-tested. Starter passed but did sound like it ran long enough in other words it sounded like it spun but slowed down to fast the machine passed it though. All connections have been cleaned. Still no start the starter solenoid is good. What to do now?

850 amps is nice, but without volts the engine won't start. Sounds like dead batteries to me. The book says you must have 10.5 volts while cranking or the IDM won't fire the injectors. Are you getting any smoke while trying to start? If not then you really need to check the vehicle voltage like Clint suggested a few posts earlier.

Hope this helps.

I have had 2 fords with the 7.3 and on both the starter went bad and you could swear your batteries are dead. I put a new starter in both times and all was great! Not saying it's your problem butt it was mine twice. Good luck

Good point. A bad starter could have a huge drain on the batteries and cause the voltage to fall below 10.5v. Normally with bad batteries, the engine will crank quite quickly but still not start. With a bad starter, it will slow down while cranking as the starter heats up.

Again, checking voltage while cranking will give some clues. Might want to disable the GP relay so you don't have unnecessary drain while trouble shooting the issue.

Are you sure that you actually measured 850 amps coming out of the batteries? That is about 10,000 watts or 13 horsepower, no starter in a 7.3 needs the equivalent of 12 hp to spin. I'm guessing, but I seem to remember reading that under normal conditions the starter draws about 300 amps to start the truck (normal, I mean not extreme cold conditions when fluids don't flow as well). If you measured 850 amp, I'd look at starter first. Oh and the GP's would add another 100 amps to the draw...a good reason to install a GPR light so you don't start the vehicle while the GPR is still drawing amperage from the batteries.

Thanks for all the help
 

New starter installed. Cranked on first try. Thank you for all the help.

Glad you got her fixed ! thx for reporting back..

What Clint said :-wink^^^^

:-bigparty

Thanks for the update. Did you have to give up your original started as a core? If not, then you might consider having it rebuilt by a reputable shop in your area. There has been a rash of aftermarket starter failures so you might not get the same life out of the replacement part (unless you went with an OEM part...)

Glad to hear you are back up and running!

7.3 Won't start on 1st try but normally always on the 2nd
 

Just saw this thread and thought I'd try it out. What do you guys think could be my problem? I have a 1999 F250 with the 7.3 and 61,000 miles. Always garaged kept in in great shape but here's the problem:
This truck does the exact same thing EVERY time... Turn the key on, wait till the "wait to start" light goes out then try to start it. It will crank for a short time and act like the batteries are going down but not start. Then I shut the key off and immediately try the same sequence again, only the second time around, it starts like a new truck. New batteries and new glow plug relay. Are there any 7.3 gurus out there that can help?? Not really wanting to take it somewhere and spend a fortune for something I might be able to do myself with a little help.
Thanks!!

Just went thru this yesterday.




New Batteries, 2 year old starter, cleaned and inspected as well as bench tested everything.


Bought a new starter...........




VROOOOM.


Denny