New 1996 CCLB 3500 454. Help set my expectations on power or is there a problem

[brycebba]

Yeah, I undid the bolts on the rail but it lifted up just enough that I could slide the injectors out. It didn't look like the supply line was loose or anything but I'm new to this

- Bryce -

 

[brycebba]

So here are my questions that I have and maybe what I can do to test them.
1. What should the fuel pump pressure be if I plugged the gauge right into the line coming from the tank

2. I noticed that sometimes my voltage gauge drops a couple ticks below 14 while the truck is running. I went to actually check voltage and my multimeter died so I need to get another one. What would a voltage be that would start to decrease pump pressure below what it should push

3. I plan to look for possible pressure bleeding since I cant see any evidence of fuel leaking. Are the places I should around the parts I replaced accessible or is it ultimately easier to just pull the intake off again?

4. The little hose that connects to the FPR I have heard can crack when you pull it off, what would the symptoms be if it did crack?

5. Is it possible that the supply line pre-FPR has a minor leak that is dropping pressure or causing bleed off like was told a few posts back and that is making it hard for fuel to get back to the engine after it has been parked for a while?

Sorry for all the questions! I really want to learn and not rely on mechanics for some of this stuff. I have been pretty handy in the past but havent done much with big engines and would love to teach my sons as they grow up.

 

[someotherguy]

The line to the FPR should have been replaced while you were in there. Last one I worked on crumbled when I touched it. Correct vacuum signal to the FPR is pretty important.

Richard

 

[brycebba]

What does that line go to?

 

[someotherguy]

Vacuum source from the rear of the intake.

 

[brycebba]

Sorry for the dumb question but can that be accessed without taking the intake off? Its been pouring rain here all weak so I havent had any chance to do anything but I could pull it this weekend if I need to. Say that it is cracked or something, what kind of problem does that cause? I would guess it would be the same as a bad FPR but that's just a guess

 

[someotherguy]

I'm not going to say it's impossible but I'm going to bet it's extremely difficult with the intake installed. Consider where the FPR lives - right there under the end of the plenum. That's the area you're working in. You could try using a small mirror and bright light to see the area but I have my doubts.

Be sure to use line rated for vapor applications; you don't want some plain rubber hose on there like windshield washer line; the oil/fuel vapors will destroy it quickly.

Vacuum signal drops in relation to quick opening of the throttle, and under load; the FPR is vacuum referenced to up the pressure as needed...it also drops pressure when it's not needed. This is why you expect to see a spike in the pressure as you blip the throttle. Kind of a rough and simple description but that's the gist of it.

Richard

 

[brycebba]

Sounds like to do things right and check everything I need to pull the plenum off again... When I take it off and seal up the ports can I cycle the key on to see if I can find a leak and test pressure again or is that a problem?

 

[VorTecxas]

Yes, you can safely cycle the pump with the upper plenum off

 

[VorTecxas]

As long as your lines, etc are sealed. That's what I mentioned earlier. The line pre-regulator will have considerably more pressure, I believe the free-flow pressure is above 100PSI