2008 Ford F250 5.4L drove to store shutoff and tried to restart and would only click. I jump started, drove home and tried to restart and there is nothing with the key on. I bought a new battery and still nothing with the key on, but it will start and run when jumped. As soon as the jumper cables are removed it dies. Any suggestions on what to check next?

 

I would start by cleaning the battery cable terminals. Then, put the battery on a good charger until it's fully charged.

 

If a vehicle starts and runs when a jump is applied then dies when you disconnect a jump cable the alternator is faulty and is not making power.

Take the new battery and have it load tested. It may be dead. A bad alternator will kill a battery.

 

The battery cables are clean. When the new battery was put in the lights came on for about 10 second before everything went dead, but it will still start and run as long as it is being jumped. I will try a new alternator. I just wanted to see if anybody might know of a possible simple fix before I pulled the alternator.
Thanks for the help.

 

I recommend starting with shorebird's recommendation. Have your battery(ies) load tested. Mine were showing fine at 11.7VDC but my cells were dead and wouldn't take any load (0.1VDC when a load was applied). Just about any auto parts store will load test them for free.

It sounds like your battery is your starting problem. My guess is the longer it sits, the harder it is to start (or won't start). That's the same problem I had. If I let it sit overnight it was a 50/50 chance it would crank over and start in the morning.

To check the alternator, start the truck and let it idle. Using a voltmeter take a Volts DC reading across the (+) and (-) terminals of the battery. The rated output of your alternator is 14.4VDC, but that will be at a higher RPM. If your voltmeter reads anything over 13VDC you are probably good and your alternator is at least working and trying to do its job of charging your battery. If not, that is probably the culprit.

There are too many possibilities to list of what might be the problem, but hopefully this gives you something to work with. I am by no means a certified wrencher but I have dealt with my share of electrical issues. If your cable connections are clean, I would also make sure that your starter is mounted solidly (no loose bolts) and the connections are clean and solid too. My last issue was due to a dying starter so don't rule anything out.

Best of luck and welcome to FTE!

 

The alternator was bad.
Brian42 great write up, but it would not stay running on its own to test. The thing that had me stumped was it drained the "new" store battery in 10 seconds, but as shorebird said "A bad alternator will kill a battery". I just didn't know it would be that fast.
Thanks again for everyone willing to help.

 

If it Killed the battery that fast, Its a good thing that the battery didn't explode on you. I have seen it happen before. the alt was shorted on the inside and made a direct ground to the positive wire and the battery exploded on my friend burning him with acid.. He got very lucky he was not over the battery.. If you have Two battery's in your truck, Its almost a must to replace both. As a weak battery in a set will also kill a new battery..