belt tensonor
 

My belt tensonor is a bit loose and shakes a little was looked at it and can't find where to tighten it does anyone know how or a site that shows it....would that have anything to do with my problems starting the car? Still can't find whats causing the starting problem battery is fine starter is fine alternator is fine....it just seems to reset itself when I try starting it and when it does start its fine I am at a lose for words

Sounds like you need a new tensinor, as for you car not starting what do you by it " resets itself "?

Al

seems like the pcm resets itself. The speedo and rpm needles jump up about half way and the trip resets. Runs fine when started but won't turn over when trying to start

Reseting of the speedo and trip was a common problem on 99's, usally it was caused by a weak battery......if you can I would try a new battery. JMO

The trip and everything reseting is a problem but my main problem is the car has problems starting it might start one out of every ten tries. The battery isn't weak I tested that the other day and its puting out 12.5v. Could I possibly have a loose ground somewhere?

Is that with the engine running, also have you checked what the volts are while cracking the engine over?

My '96 Z28 did the same thing. My battery even tested ok. I took my dad's battery out of his Tahoe and the car started right up with no problems.

get the battery tested

a voltage reading doesn't tell the whole story ... amps is what turns the starter

I have a multimeter to check the amps the bat is putting out what is a good reading?

Don't even try to measure starter current with a multimeter, its probably 250+A. If the meter's got a fast max-min capture set it to volts and find the lowest value the terminal voltage falls to when you try to start the engine. I'm not sure what the PCMs are sensitive to on these, but it should be no less than around 8V at in 50-70degree weather. Slower capture (>10ms) will only show the mean cranking current dip, probably 10-11V.
If you haven't got those facilities, take the battery to an auto parts store, most have load testers that draw current through a big resistor to check the voltage fall.