Yep. While accelerating, at about 4000 to 5000 rpm the battery light comes on and the guages on the right side of the dash shut off... drop to zero. The tach and speedo still work.

This condition continues for 2 to 5 sec and whether I let off the gas or not it corrects itself. Sometimes after the battery light goes off the Low Fuel light comes on and sometimes the Security light comes on.

WTF??

 

Maybe the alternator is going bad, it cant keep up at higher RPM & all the Juice it's taking to fire the coils & run the fans at that speed is enough voltage drop that it displays the battery message. I Don't know, Just a thought. Or the belt is not spining the alternator at that speed, Centrifigal force.? Just another Thought. Yeah I Been drinkin, so what Lol & Now I'm gonna go tune someone elses truck. (Just Kidding)

 

I think I have read about this problem before on this forum, Might try a search ( I will in a few min). I think they found the cluster was bad????????????

 

Speaking of belt slip, what size belt are you running with that 2.8 pulley?

 

Not sure of the size but when Zippy was trying to tune it he threw a belt. We bought one that is 10mm shorter than the stock Radix kit belt. The number ended in 10 instead of 20.

I have the 2.8 pulley but added some pulley size when I put on the 100mm Metco pulleys. Just went out to measure and the stock pulleys are 90mm so I added 20mm to the pulley size there. That would be about .75" added to the pulley size and the 2.8 pulley would be about .6" reduced from the stock Radix pulley so I'm thinking that the new belt should be short enough. Is my thinking correct?

 

Why would the "short" only occur at relatively high rpm's? Any thoughts... anybody? I gotta try a shorter belt today... but why the Low Fuel and/or Security lights? I wound it up some last night and had the same results.

 

low fuel and security lights might be just a by-product of the problem. The battery light though might be right. We had 2 vans (ford) that suffered the same symptoms and it turned out being a really nasty looking battery ground wire on one and the alternator to battery cable on the other was corroded just under the installation at the battery. Couldn't see it. Of course our vans aren't like your truck I am sure...they are severely abused and neglected.

 

Seems to me that the stock Radix belt with the 3.4" pulley is something like 112.5" Crunching the numbers, I only see about 1/2" difference between that and what you would need so 10mm sounds right. I took into consideration: the difference to the top of the pulley, amount of pulley wrap and the extra belt deflection with the larger idlers. Did I miss anything? Maybe try about 1 inch shorter than stock. Is the deflection on the tensioner similar to the stock Radix setup?

 

I'm using the Radix tensioner.

1 inch shorter than stock would be about another 15mm. I'm not sure I could get that belt onto the pulleys. I think maybe I can get 10mm to load and that should be quite tight, but the only issue I'm having is the battery and other lights coming on and there is a new development in that area.

This morning I was driving at normal speed, not revved up or anything, and the Security light came on briefly. Beats me.

 

I meant, does the tensioner look like it is as tight as with the original Radix setup. But it sounds like you have it pretty tight already.

Did you have to do the security relearn procedure(or whatever it is called)? Looks like you did a PCM swap for the new tune.