Some background, my truck has been sitting in the garage for a good month and I haven't started it. Been putting in 6 days a week for over 2 months at work, 60+ hour weeks. I have a company truck so that's what I've been driving, and the few times the wife and I have gone places we have used her car.
Today, I start the truck, it immediately dies. Successive attempts same result, blue smoke out the exhaust. I kept it running by revving it up but then it dies again. It's the original battery, 5+ years old now. MM shows 12v at rest, drops while cranking. I put the charger on the battery for a bit while I came inside to ask this, it's on trickle 2A and its at a 7 on the dial, and it goes to zero when fully charged.
I've been thinking I'll need to replace the battery before winter, but I'm hoping it's just that since its discharged that's why it won't stay running? Any thoughts? I have had zero issues with this truck but having a company truck over a year now, it sees very limited action. 2010 5.4 with just a tick over 40K, oil is good, air filter is clean and free of obstructions. We do live in the woods and have critters that hang out in the garage, like squirrels and chipmunks but I'm not seeing any evidence of chewed wires that I can see. It's in the garage and using a droplight I don't see anything obvious. Thanks in advance for suggestions, waiting for it to charge. Maybe it's as simple as I have to take the work truck and get a new battery I hope

 

Took the battery out, eye was red. Went to Advance auto and got a silver 750 CCA, put it in the truck and it's still doing it. Put the charger on the new battery, about half charged. Waiting for it to charge to see what happens next

 

Tim...I would suggest replacing the battery. More often than not those trickle chargers kill the battery over time. There are some chargers out there that ONLY charge when it is needed which does help save the life of the battery. Sometimes batteries can charge well and test fine...but when under load they fail due to a bad cell.

Blue smoke is an indication of a little oil burn but sitting like that it is possible to have some oil burn initially. (oil past valve guides etc.)

 

Hmm that is ofd that you would have to charge a new battery that much. What does the truck call for as far as CCA?

 

Factory was 650 CCA I replaced it with 750 CCA. Depends how long the new one was sitting in the store I expected to have to charge it. Making myself some lunch while it charges, fingers crossed. I can't understand why it starts every time but dies right away

 

Chumley- it takes a digital meter to acurately do this. A battery that is fully charged will measure 12.6 volts. A battery that measures 12.4 is only at 75% of its capacity. I worked in a battery shop for years and this has always been the standard- saying that I am aware of a 12.5 volt battery causing problems to my surprise!

Oldstuff

 

I was using a digital multi meter, and when I removed the old battery thats when I saw the red eye and thought "duh!" I'm hoping when the new battery is fully charged my issue will be resolved and it will run like it should. Am I assuming too much?

 

Of course I have to blame my wife for this. Whenever we were going somewhere on the weekend I'd say let's take the truck and she would decline. I must admit her Q5 is a nicer ride but my trucks no slouch either.

 

Dumped 5 gallons of fresh gas and fuel treatment in it, it revs but still won't idle. It just keeps dying. I'm stumped, and very irritated

 

Sounds like you have a couple of issues. A weak battery should not cause the engine to stall. As soon as it starts, the alternator should be putting out enough juice to keep the voltage up to running state.

The blue smoke is a little worrying. It's an indication of burning oil, but might be also be attributed to sitting for a month. You didn't mention if the blue smoke happens on the 2nd, 3rd, etc. starts. If it is always doing it, you may have some other issue going on.

However, if it doesn't run, I would expect it to be throwing codes. Have you got a scanner, or can you borrow one? It would be worth it to see what codes it might be indicating.

 

Blue smoke is gone, figuring it was just from sitting. I was charging the battery itself but I vaguely remember reading about hooking neg to something other than the battery. I just hooked the ground to the rad support, IIRC it was something about the memory and not letting the truck know it was recharged. I'm going to look in the owners manual. I just tested the battery and it's at 12.6 at rest with MM. Gonna let it charge as its set up now and check for that info in the manual
I have an SCT X3 I'm going to see if it has any codes. I did find a dead mouse stuck under the A/C line mounted to the x member under the radiator, I was all over the engine and underneath with the drop light and nothing stood out.

 

Chumley- Your situation is similar to mine- that is why I am taking note of it, my 2010 5.4 only has 38,000 miles and does sit as long as 6 weeks sometimes. I am wondering that maybe you have 2 problems- battery and possibbly bad gas? When i know mine is going to sit more than a couple of weeks I put Stabil in it. Good luck and keep us updated.

Oldstuff

 

X3 shows no DTCs, bad gas is definitely a possibility. I had put new gas in it maybe 2 weeks before it sat, and I just dumped 5 gal of fresher gas in it. If I could get it to stay running I'd beat on it a little but the tank is almost full now. Maybe I'll go get 5 more gal after dinner and dump as much in it as she will take, and drive it if it will stay running at idle. I'm pretty sure it's my own stupid fault for not using stabil or I usually use StarTron for the saws/bike/mower. I'd be willing to bet it's crappy gas at this point
Edit: I'm ruling out the battery at this point, it's new and should be fully charged shortly

 

I just can't see fuel going bad in that short amount of time...I have left fuel in my boat for months without starting it and had no issues. I have seen a video of someone with the 5.4 in their F150 and they replaced the IAC (Idle Air Control) motor. It apparently sticks due to carbon build-up, don't know if your year truck still has one or not but it's worth a look!

Here is a video on it:

 

Fires but won't run? Throttle body

The 2004+ 5.4L doesn't have the IAC, so we can rule out that one, but Rob that's a good video find!

I'd pull the throttle body and give it a gentle clean. Careful what you clean it with as it's incredibly sensitive. I'm trying to recall what NOT to use and carb cleaner comes to mind. If I recall correctly, most people use MAF Sensor cleaner.