7.3 no start

[Denver]

I took the batteries out and had them tested at Napa. They failed. 1 year old motorcrafts. 850cca. Napa testing device showed one was only producing low 500's cca at 12.4 volts and the other was high 400's cca at 12.3 volts. Ended up getting new Napa batteries as the Fords were a warranty set and the prorate would probably be little by now.

Installed the Napa ones and it started right up. Key off was showing 12.6 volts. Key on 12.1 volts. Key on starting it went to 11.3 volts. Charging volts is 14.46 within a minute, maybe 20 - 30 seconds after start. Haven't driven the truck yet but have a battery tender on them topping off the voltage.

I'll see if replacing the batteries fixes this intermittent no start issue. I'll report back over time. This was a first though for finding out the batteries were bad. Usually it's just been a slow crank right away or they are just dead. This one threw me off as it turned over strong, for about 20 - 30 seconds though and then it got slow. They were also a year old. I've had some batteries go dead in a year but was usually only one of the two, instead of both.

[Denver]

Originally Posted by CTC DEEZUL

Hows the big power wire that's behind driver battery that's right atop the fender well? See if it's clean

It looks good and is tight on the stud at the battery. I was taking a strong look at it. There is a connection right behind the airbox on the fender liner I was thinking of messing with. Is it some type of breaker or fusible link?

[CTC DEEZUL]

No that's the cab /fusebox power feed connection. I wanted to make sure he's good. Very intermittent issues there

[CTC DEEZUL]

Do you have a chip in the PCM?

[lincolnlocker]

Batteries and alternator can play a huge roll in run ability issues...

live life full throttle

[Denver]

Originally Posted by CTC DEEZUL

Do you have a chip in the PCM?

No chip or tune in the truck and it's never had one.

[CTC DEEZUL]

I'd back probe all powers at IDM PCM while cranking and see what's getting good power

[CTC DEEZUL]

Or send them both to Johnathon so he can test them both on the bench. It really does clear up potential issues with them and eliminates alot of guess work and dio