Engine/Transmission (1998.5 - 2002) loosing power n boost

[rbarr]

Noticed fuel pressure dropping off every now and then a couple weeks ago so I baught a new transfer pump. Pressures used to be around 16psi @ idle and 11psi @ WOT. Now thry're at 14psi @ idle and 8 @ WOT. They drop to 9psi after running a while and comming to a stop. Before replacing I thought I'd replace overflow valve(cheaper). No difference. 3 days later fp dropped to 5psi. Replaced tp asap(already baught new vp44 30,000 miles ago from bad fuel pump). During this whole procedd I noticed my boost dropped from 34 to 27 without fuel box and from 46 to37 w/box. Fuel psi is now around 14psi @ idle and 9@wot. I have noticed more smoke(black) under acceleration wo box but power hasn"t seemed to change much. Also checked tps voltage @ wot and it's onlt 3. 5v. Shouldn"t it be around 5v? No codes in system. Any ideas needed. Thanks n paraniod, Ryan

Truck is a 99 3500, 5in exhaust, BD step 4's, powermax3, n Banks intake

 

[Jetson]

Check the easy stuff first like all the clamps on the intake hoses. I doubt your lower boost is due to fuel pressure. Mine was a little lower recently due to low MAP sensor voltage. I unplugged and plugged the connections 3 times and don't have any more problem with it. It doesn't take much of a bad connection to drop the voltage reading on a sensor that operates at only 1 to 5 volts.



I don't know the TPS voltage readings, would have to check my manual.

 

[rbarr]

I checked all clamps and connections-ok. Need to pressure test though. Also noticed while running @ 55mph I only run 1-3lbs of boost on flat ground. Used to be 5-8. Will check map sensor & connections though. Still orig and never out. But still, why SO much more smoke??? Thanks for input, Ryan

 

[GarrettPetersen]

Hows your air filter look. dirty air filter will cause black smoke

 

[rbarr]

Brand new BHAF 2 months ago

 

[Jetson]

You might try cleaning or even replacing the IAT sensor.

The extra smoke is due to the reduced boost. You could be having a turbo or exhaust problem, but that is less likely than some electronic measurement problem. The black smoke would tend to say that the VP44 is pumping the fuel. It's just not getting enough air to burn it all. You haven't noticed a different sound coming from the turbo have you? The stock turbo REALLY doesn't like to run over 40 psi.

 

[rbarr]

I cleaned the map sensor tonight and it made no difference. checked elec. connections at ecm- OK. I've got a new HX-40 in the back seat- mabye I should put it on and try it. I haven't heard any new sounds like whyning but maybe its on its way. Guess I'll find out. Either that or I've got an air leak some where.