It's really hard to tell, becuase I might just be to 'used' to the power now, but it feels like I'm a little down on power in my truck. My lift pump pressure, measured by tapping the fuel filter at the output side, is 15psi at idle, dropping to 9psi at WOT going up a long freeway onramp.
The last 10% of the throttle doesn't seem to add any power, but it DOES generate a bit of screeching noise which MAY be coming from the VP44. Starts easily, no white smoke, no codes. It's bone stock (inlcuding origina lift pump) 3.55 rear, 150,000 miles. No guages except fuel pressure.
Anybody else get that screeching? I don't know how else to descibe it.

 

Have you had the valves adjusted yet? At 150k, your due.

 

Good point, that's what I plan to do this weekend (weather permitting).

 

Screeching? That's hard to place.

If the last little bit of pedal doesn't add any power, then it could be the APPS.

It's hard to prove a negative, right?

 

I finally got off my backside and checked the valve lash. Since all were within tolerance, that's not the problem. I think the 'problem' may be that I've gotten used to the power it has (relative to trucks I've owned in the past) and it's having a hard time impressing me.
About the valve 'adjustment': First, I was amazed at how clean everything under the valve cover was. The inside of the valve cover itself was CLEAN. Second, if you're going to check your valves, don't assume just because the truck has 150,000 miles on it that you need to replace the gasket. I did, but only because I already bought it. Third, if you've ever adjusted valves before, this will be super easy for you. The only hard part is REACHING for #5 and #6
Total job took me less than an hour. I think I'll just drive it, and forget about my senseless worries.

 

Do you have a boost gage?

My truck starts screeching from time to time when the boost comes up and it always means that the exhaust manifold bolts have loosened up. It sorta sounds like finger nails across a chalk board if your old enough to know what that sounds like. Check your exhaust manifold bolts.

 

Chalk boards? That's new technology! When I was a kid, we had ROCKS.... and we liked it!
Thanks, I'll check out the exhaust manifold.