Ive got a few more problems with my truck that I'd like to fix while I have the extra cash. Heres the list: My temperate gauge inside the truck always says cold, even during real hot days; My battery only lasts a week and then has to be recharged; I've got dual tanks, but the front one works very rarely; My speedometer fluctuates everytime I turn a corner and sometimes it never goes back to where it was before I turned the corner, And my airbag light blinks the code 51. I got the alternator checked and it tested fine, So I know that it isnt the thing running my battery down. I found a short on a wire hooked to my fuse box and I found a short on the wire that connects the starter to the battery, fixed both of them and battery still isnt holding. Battery just got replaced a week ago because the old one was found to be defective, they checked this battery said it held but im still having problems. My volt meter reads 12.78 when the battery is fully charged and by the morning its down to 10.
Hopefully yall can help me out. Wanna get this truck up and running fine so I can put another 170k miles on the 170 it already has. Put new U joints on it last weekend, and it was running great... until the battery problem began again.

 

I hate to be the pessimist here but if you are getting a battery drain it could be almost anything. Best I could say is to pull one fuse a night till you dont see a drain and when you've got it narrowed down trace the harness and start disconnecting or replacing parts.

 

The temp gauge is either the gauge itself (unlikely), the wiring (somewhat likely) or the sender (most likely). If it moves even a little, then replace the thermostat with a 195.

Front tank - check the wiring to the pump and the switch in the dash.

Speedo - take the VSS out of the rear axle and clean it off with a rag. 99% of the time that fixes the problem.

You can also trace the battery drain by putting am ammeter in line between the battery and cable. Start pulling fuses until the current drops off and you've got your circuit. Unfortunately, the next part is hard.

Can't help with the airbag, unfortunately.

 

Found another short, this time on the alternator. Fixed it and the battery has held for 3 hours. Gonna check out the wiring on the front pump tomorrow when I get home from work and look at the other problems this weekend. Anyone got any help for me with the airbag code?

 

95 manual lists code 51 as intermittant short to ground that blows the diagnostic monitor fuse (Internal) - says short in system must be repaired prior to replacing diagnostic monitor or fuse will blow again requiring replacement of diagnostic monitor repeatedly without fixing the problem. Short could be in any sensor or the wiring to the sliding contact (clocksprong) in the steeering column. Good luck.

 

I'll just note, they are all common and frequent problems with most of our F-series trucks. You are in no way alone or the first person to have any or all of those same bugs. I bet you could find lots of info by using the search feature here. I can't count how many threads I read about the same problems you mentioned.
The alternator must be putting out 13.5 volts while running, maybe the battery isn't charging. I wouldn't trust that alternator, does your alternator have two plastic wiring connectors going into it, and an external cooling fan under the pulley?