The best way to test the true condition of your battery is with a load tester. If you do not have one most shops do and you can take your battery and test it. They may even let you borrow it. Even though you see 12.8 vdc on your battery it still may fail load testing

I had a similar problem..... I fixed it the easy way. I ran a 4 gauge cable from the batt switch to a block under the dash, also a 4 gauge ground cable direct from the battery. reterminated ALL the grounds & wire connectors to this new ground (zero ohms to ground!) block. Fed all the fuse blocks, instruments, lights & sound stuff to the new 12v block. No more problems, period!

interesting that this thread would pop up after so many months....
my slow cranking was the starter..i replaced it with a high torque starter and she spins great...
the issue of the gauges dropping when additional accessories were turned on was just diagnosed this week....i was having some other work done and the guys at gt performance found at least two splices in the main 12vdc wire from the engine compartment to the dash...additionally, there was a 16 gauge wire (hidden nicely in a taped up wire harness) from the main fuse block to the starter switch...the previous owner did some "rework" and obviously failed electrical 101...
any wonder the thing ran at all.....

my lesson learned...
check everything with the ohm meter and measure voltage drops..
undo the taped up wire harnesses and visually inspect..


hope this helps...

gary

I have a hunch it is the starter on my boat also. I need to get someone to help me measure the drop at the starter while I crank the engine over. As for the stereo going off and coming back on when I turn an accessory on, I think I can live with that for a little while, until I really get bored, then I think I will tackle that. Anyway what was the price on the new starter if you don't mind me asking? Thanks - Eric

You know when you said its interesting that this topic came up after being a few months old. I found this topic by using the search option. I entered slow cranking engine and your topic came up. Unbelievable, this website really has its stuff together. I bet there are a lot of users that don't know you can do that. I just found out myself. Anyway thanks for your input. Eric

i got the starter from gt performance...they get them from a guy in parker, az...i forget the name...

as i recall it was around $150....

i might have the box at home...i'll check the name

Thanks for your help.