Soo I picked up a 1999 chevy tracker last August with 90,000 miles on it for $600, since then I've had to do a few little fixes here and there but for the most part the thing is solid. The only thing that's not working properly right now is my front wheels won't engage when I activate 4wheel but I'm fairly sure it's the air actuator pump...that's why I need some help. I've been looking for some manual locking hubs to put in the front for a while as well as a hard top for the roof! If anybody could help point me in the right direction for either I would greatly appreciate it

Go to fixkick.com and search for 4WD Lock Hub.
And try this parts search engine too.

Car-Part.com

Welcome to ZW
There have been a some members here that have had the same issues and several different fixes.  I'm sure that answers will be coming shortly.

First - manual free-wheel-hubs - anything that fits the 89~98 Sidekick/Tracker will bolt on - I'm using SuperWinch hubs that I got from Amazon.com - please note however, that the front differential's internal free wheel mechanism has to be engaged for drive to get to whatever hubs you choose.

There are a couple of different ways to deal with the front diff's internal free wheel mechanism ranging from forcing it to stay engaged, either by welding, or fitting a spacer, this spacer can be as simple as a handful of appropriately sized nylon cable ties, to replacing the front diff with one from an 89~98 Sidekick/Tracker.

Second - diagnosing & repairing the front diff's free wheel mechanism...

This is controlled by a little air pump on the back of the bumper reinforcement - look just under the right side of the radiator - for test purposes you just need the ignition on, the engine does not need to run.  If you're working in a quiet place, you might be able to hear the pump start & stop from the driver's seat - the pump should start and run for anywhere between 1~10 seconds when 4H or 4L is selected, with the ignition on - if you don't hear it, get a volt meter or a 12V test light and let's get started.

Find the wiring connector for the pump and unplug it - there are three wires, red, black & pink - connect the lamp or meter to the black & red - you should get 12V or the lamp lit for 10 seconds when 4H or 4L is selected - if you don't the problem will be one of the following - the 4WD switch on the transfer case, the ECU (or 4WD controller) or a broken wire.

If the pump does run - how long does it run for?  Under normal circumstances it should run for 1~2 seconds and stop, at which time the mechanism would have engaged - if the mechanism does not engage, the pump runs for 10 seconds and then the ECU will shut it off - how long does your pump run?

If the pump runs for 10 seconds and stops follow the rubber hoses that attach to it - one (the inlet) connects to a metal line that runs up the radiator support  the other (the outlet) connects to a metal tube that runs along the frame rail and connects to the front diff - disconnect the output hose, cap the pump outlet, and cycle the transfer case shifter to 2H and back to 4H - how long does it run for now?

Let me know the outcome of the above tests and I tell you where to go next.

Wow thank you guys for all the info! So if I   were to force the internal free wheel mechanism by welding or tying it would that make it so my tracker is always in 4wheel? Or would 4 wheel still only be engaged when switched into 4L or 4H (with manual locking hubs). I'll have to try out that actuator pump test ya'll suggested this weekend and I'll post my results!

The transfer case is primarily what will determine if you're in 2WD or 4WD - that sends the drive to the front axle.  Having a front axle with a free wheel mechanism, whether automatic or manual, allows less wear & tear on the axle and perhaps slightly better fuel economy - there are thousands of 4WDs running around without free wheeling front axles, and probably thousands more where the free wheel hubs are always in 4x4

This weekend I got a bunch of new tools to start cracking away at the 4wheel drive system, and of course as soon as I get home and get ready to work on it something else goes wrong! (fuck you Murphy and your damn laws). The tracker is lurching and stalling really bad soo im fairlyou certain it is the crankshaft position sensor. From the research of done soo far it says you must remove the transmission in order to gain access to the CPS...is this true or can I replace this thing without dropping my tranny? (I dont want to have to go out and buy a tranny jack if I don't have too right now)

What makes you think the problem is related to the crankshaft position sensor (CKP) - it's my understanding that the CKP sensor is there for misfire detection and the engine will run fine without it (it will set a code).

Are you perhaps confusing the camshaft position sensor (CMP) and the crankshaft position sensor (CKP)?

You are correct I got the two confused. But I think it's the crankshaft position sensor because Ivery been having really random power loss and the tracker starts lurching really bad like it's not getting enough fuel than stalls out. There's no noise coming from the transmission and the clutch seems completely fine as well which makes me thing it's gotta be a sensor of some sort