I just got thru rebuilding the trans on my '99 4l60E trans that had a bad 2/3 shift. I put the best money can buy as far as I know in it, got a lot of info from in here, I havin a problem with no pump pressure after the rebuild and the front pump is new. Trans go shift kit, been air checked after the pump , all checks out. Replaced the front pump again, still the same thing. Could it be the torque converter or a problem with the valve body? What could I be over looking? At 4 grand the speedo will raise up to about 45 mph and then fall off to 0. I even had a transmission guy look at it and he does not know either. Where could the pressure loss come from? The level in the pan never lowers, I could sure use some advise on this one

 

What gear is this in? Does it shift good?

 

Take it to Century Automotive in Rosenburg.
Mike can tell you what is wrong with it.
and fix it where it is as good as new.
http://www.centurytransmission.com/

 

have you put a transmission line pressure gauge on it to check, maybe the torque converter isnt splining to the pump right and not spinning it making no pressure, it could be you p/c solenoid not installed correctly or leaking around the o-ring. just some suggestion, good luck