We have a 99 F350 Diesel truck, it will crank but will not roll over. To get it started, most days, we have to jump it. We have had the batteries and the alternator checked and they are fine. It seems that there must be something draining the batteries, but we cannot find it. Anyone have any ideas what it may be, or what else we could try?

 

Welcome to FTE.
You say it ''will crank but not roll over''.Are you sure those batts are good.It will take at least 10.2 volts for it to fire.If one of them is bad it will not start.I assume it has been running fine?Is this a stock truck or does it have mods?

 

^^^ What Barry said ^^^^

Also if new or fully charged batteries will not work, Check fuse #30 under the dash, oil level too. If the oil is really low, then check the oil level in the HPOP. Should be about 1/2 inch from the top

 

Both batteries are less than an a year old! We had both batteries checked and they are good. We also had the alternator checked and it is good as well. This is a stock truck. I will check Fuse #30 (what is that for) and the oil level.... we have had an oil leak in the past but never had this problem (bad oil pan)! We have also talked with a ford mechanic and another mechanic.....one said that if there is something drawing from the batteries when you disconnect them it should spark the other said not necessarliy....either way we arent getting a spark! Weve checked everythning they have suggested.

 

If the #30 fuse is blown, unplug the fuel bowl heater, (plug on the back side of the fuel bowl). Then replace the fuse and try again leaving the heater unplugged. From what others have posted in here, unless you live in an extreme cold climate, you shouldn't need it. But either way, if that is the issue then replacing is pretty easy as well.

You won't alway get a spark when disconnecting or connecting the batteries. Kind of like hooking up jumper cables. Sometimes they spark, sometimes they don't. That won't really tell you anything.

Hang in there. I am sure there will be others that will chime in soon with more ideas. Put a meter on the batteries and check to see what voltage you have while you are cranking.