1999 Chevy 3500 PU 5.7l gas. No power to starter there is one fuse #8 called "crank" that does not have power to it fuse is good just no power to it fuses to the left and right are good. All other fuses inside and in engine compartment good starter relay clicks and replaced with a new one anyway.Coulkd it be a key problem?

check the under hood fuse block/relay box,ive seen these go bad, i see you said starter was checked how was it check .also check to see if getting power to starter when you turn to crank,will have to have friend help you,if the test light lights up,give that starter a big smack with bfh! is there a sercurity light coming on and staying on,if so check your key,it could be worn out.there is a starter relay that controls starting is this a stck or auto,good luck,mike

check for loose grounds and powers-in need of cleaning-at the Battery

if it dont crank how would you say the starter is good.
you dont know that. sorry'
making assumptions is the top killer of all diagnosis.
you set in driver seat:
i key on, is the CEL ,charge and BRAKE lamps glowing
if not you lost all power ,12vdc to dash and ignition.
they must glow, if not the battery is drained or a fuse is blow.
check all fuses , now.
if all those normal lamps glow, (warnings) per the operator guide.
the good, you have 12v power.
proceed to cranking..
"as they say, Call the Auto Club time"
the first check, is called a jumper cable jump start off a running car.
if that works, then the starter is good and the battery was ONLY discharged. (no assumptions. see?)

then and only then could you say, starter is good. see?
if the car JUMP passes ,then battery bad or charge system failure....
(ask for help that topic, "my battery is drained, why?"
if the JUMP fails (to other cars battery)
we then hot wire the starter, does starter crank fast and robustly>>?
yes?, then the key line is bad.
no ?, then the starter is bad. or its 2 huge cables are bad.

YES?? starter hot wires good. then? !!!!
see the tricks here,
my guess is this car is A/T tranny, Automatic.

http://www.fixkick.com/nocrank.html#tricks


this page also teaches , hotwiring any starter , safely.

You have power on the battery cable terminal, and the purple wire coming from the neutral safety switch ?
Can you jumper the solenoid and make it crank ?

Check the fusible links (at the starter main post)
Look like normal wires but the last few inches by the
starter are a fuse ,sometimes they can burn out and not
be burnt through the covering on the wire,a gentle tug will verify that.
Could jump the terminals there also,to be sure the starter is ok.
Just make sure it's in netural first !!!
Also,,When the starter brushes get worn,sometimes there is not
a good enough connection to the armature,and the starter acts just
like yours. A rap on the starter case with a hammer is often enough
to seat the brushes. If that works it's starter time

check and make sure the powrr wite has a solid cconnection the check the grounds to the starter.

there could be a bad wire somewhere between the solenoid and battery. that is the only thing i can think of if you have done everything else. I will lean towards starter relay, it should be in fuse box. if not that I would check for a bad ignition switch. not letting power to go to starter. good- day !!

Use a test light and check to see if you have power goin to the alternator. If there is no power i would start looking at the wires on the starter as chevy used this as the junction point for all the power. Look at the wires coming off the starter. You should see a couple fuse links. Fuse links look like a smaller wire transitioned into a bigger wire coming from the starter out. Upon looking at them they look fine but pull on both sides of the wire. If it feels like a rubber band then you have a open there.

check then crank positon sensor, it control the fuel system. it tell the engine computer when to send fuel

If your engine is cranking really strong make sure you have proper engine timing. If your engine is having a hard time cranking like its cranking really slow. You probably need to check your battery.