I have a 1989 auto that i am assuming has original turbo just put a boost gauge on it today . Climbing a hill at full throtle i only made 17 lbs.Holding the brakes and full throttle i only made 4 lbs. Truck just does not seem to be making power
what do yall thing is wrong

 

My basically stock '90 12v 5 speed only makes 23 PSI max and that is with an upgraded Cooler Tubz crossover tube.

 

My 91 would only make 12psi stock.

Nothing is wrong with it, just need to turn up the pump, tune, etc.

Maybe check for boost leaks.

 

The trans might not load the turbo enough sitting still like that unless you have an aftermarket converter. The 17 psi sounds about right for a stocm truck.

 

It has a low stall from goerend that dave recommended for it it just dont seem to have the power it should have

 

The engine is probably lugging when power braking because of the tight converter. Do some pump mods and it will be a different animal. You should check the fuel pressure too if it still has the diaphragm pump. It will still run with a dead pump but zero fuel pressure and less power.

 

I put a new lift pump in about 3 years ago from cummins what kind of mods should i look at

 

Simply put, when you add fuel, the increased exhaust drives the turbo harder. I would guess you're right at about zero smoke full power now. Turning up the pump will make a little more power, maybe boost to 23 or so, and also make some smoke.

That's assuming the air filter is clear, the exhaust is reasonably free, and the turbo isn't screwed up.