Electrical/charging/battery Question

[stangposse]

My 93LX 5.0 is giving me issues. It seems I can only start the car 2times before the battery doesn't have enough juice to start it a 3rd time. For instance, I'll put a brand new battery in the car and it will start right up. I'll let it run for 10mins then shut it down. I disconnect the cables and close the hood. A week later I'll do the same and it will start. However, a week later it won't crank, just do that violent clicking sound that it's done whenever I had a dead battery before. The car has a brand new alternator. It also has underdrive pulleys. When I run the car, i use no lights or accessories and I make sure the car is revving a little higher to keep the volt meter up. The charger shows that the battery is charged and even with the charger hooked up in "start" mode I still only get the crazy clicking...but the lights and radio work. However, if I slap a brand new battery in there, it'll start.

I have the original cables (they are not too bad)on the car and it's also the original starter.

Any ideas?

 

[4valvemach]

You can start with new cables and instead of the negative cable going to the water pump bolt get a longer one and run it to the motor mount.

 

[stangposse]

What does the longer negative cable do?

 

[4valvemach]

From what Ive heard moving it from the water pump/timing chain cover to the motor mount or other steel or cast iron spot helps.When I did my water pump and timing cover gaskets in my 90GT I was having hot start and low charging problems after that.My guess is that RTV or corrosion on the bolt was causing a problem and making a bad ground.My next fox will have the negative cable moved to a better spot like the motor mount

You can start with just new cables and see if it helps and keep them at the same mounting points.

my mach its at the motor mount and my 93 f150 with the 5.0 is at the passenger side of the block O.E.The 90GT the NEG cable was on one of the timing cover bolts to the block.

 

[kbsonicstang]

i had the same problem with my 88 5.0. so i changed the altenator (stock replacement) and batery cables, but it still did it. turned out to be a bad battery, so put a new one on it and havent had a problem since.

what size altenator is on it?