Tach trouble on new build

[kipo]

Finally finishing up a new build that's been in the works for several years. 

April of 2000 built truck with 6 spd.  We ppumped it with 01' wiring harness and ecm/pcm's. 

Installed the tone ring on the cam gear and just about everything else I can imagine that came on the 01'-02's. 

We are having trouble picking up the tach.  Upon start up it will register (kind of erratic) for about 15-20 seconds then drops off. 

We haven't verified it's charging but assuming its not since there is no tach. 

We swapped wiring harnesses ecm's and pcm's with known good ones off an 01'.  We've grounded and re-grounded just about everything. 

Swapped alternators, checked all fuses and relays and still can't figure it out. 

What would be the next step?  Check air gap on sensor?  Haven't swapped sensors yet but it's brand new. 

Could the 00' dash/instrument cluster have something to do with it? 

[kzimmer]

Is there any way to temp wire in a cheapo tachometer straight to the sensor to rule it out?

[jlbayes]

Is it throwing any codes related to the cam sensor? The build date doesn't tell you what year it is, the 10th character of the vin does.

[kipo]

so many codes from the ppump swap so I didn't bother to look. 

we took some measurements, found our air gap a little to big.  shaved 30 thou off sensor adapter and she's steady as a rock now.

thnx