Cat was removed and replaced with a pipe to muffler, before me.
I can't remember the fuel psi reading numbers were, it was within specs of whatever reference I used at the time two days ago. I did key on only, check psi, watch for a drop, then engine running check pressure, then unhook vac check pressure. can do again tonight. How do you test under load? Put in gear, foot on brake, apply gas pedal a little?

 

Checked this again tonight. Key on 40psi. Running 33.5psi. Giving it more throttle 33.5psi.

Re-checked TPS. It's good.

Rpm drops to 750 with iac disconnected per the dash tach.

I've searched high and low for a vac leak there's not a hose leaking anywhere. The only thing I noticed was the pic valve hose is old and kinda sucking in on itself at the top of the pvc valve.

 

I pulled a 30' 6000# camper with it today on state routes. Level ground is fine. Torque below 2000 rpm is fine. It just has no ***** above 2000 rpm. I dropped to 30mph in a 55.

 

Fuel pressure should increase as the throttle (and resulting vacuum level drops) is increased.

You can try holding the brake then apply throttle to simulate load or run the hose and gauge out to the windshield to test under real driving conditions. Just be careful to not drive too fast or pay attention to traffic.

 

How did you you perform those tests? Did you use a hand held vacuum pump/gauge to test each vacuum circuit?

Do not forget there are a few vacuum reservoirs that come into play here. And always suspect any original vinyl vacuum line.

 

Fuel pressure did not increase when the throttle was increases in park. I'll try brake torquing it.

If it does not increase while under load , yet when the regulator is disconnected it does increase, what would cause the no increase in fuel pressure while under load?

I did notice a plug wire was used for the wire between the coil and distributor cap. The coil nippl is half the size of a spark plug nipple and it could not have been making a secure connection.

 

I'll use a pump next. Oddly Propane did absolutely nothing to change the idle even when put directly into the IAC intake. Besides pulling off every hose and pinching at the source I did notice one tiny plastic hose had been chewed but that only has vacuum when the max AC is turned on as it connects to the valve that closes the vent.

 

Most likely a bad fuel pressure regulator.

 

What size tires on the truck?
What is the base timing set at with the spout removed?

 

10btdc

235/85-16

 

Used the vac pump. Tested everything forward and back. No leaks. Also drenched different areas with carb cleaner, no change. Of course I broke one of the plastic hoses.

Vac from the intake while ideling is a steady 19. Dips then tops out at 20 around 2000rpm. Disconnected spout and IAC then sprayed carb cleaner.

Only thing effecting idle was messing with hose on the pvc valve.

Egr opens at around 4- 5. The EGR control solenoid allows air to leak down. I think that's how it knocks down the pressure to the EGR.

 

There is an area to focus on and repair. As well as figure out why the fuel pressure does not rise under load.

Normal operation and test results.