Sooty #7

[Dynomite]

Originally Posted by Paul Workman

One other thought: isn't the vacuum line for the pressure regulator just about directly over the #7 plenum runner? You know where I'm going...!

I have no clue........please describe for us less familiar

[secondchance]

Originally Posted by Paul Workman

One other thought: isn't the vacuum line for the pressure regulator just about directly over the #7 plenum runner? You know where I'm going...!

Are you thinking fuel pressure regulator leaking internally dumping excess fuel into #7 cylinder?

[XfireZ51]

Originally Posted by secondchance

Are you thinking fuel pressure regulator leaking internally dumping excess fuel into #7 cylinder?

I would suspect that FP would be affected whcih would show up across the board for the plugs.

[mike100]

Poor man's leakdown test: What is the compression on one crank compared to other cylinders?

[Dynomite]

Originally Posted by XfireZ51

Well yes the PR vacuum line is by #7 but plenum volume is supplying vacuum so its hard for me to gather how it discriminates on #7.

As I recall the Fuel Pressure Regulator last time I had one fail (someone else ZR-1) there was raw gas all the way forward coming out the Air Intake in front of Throttle Body which.........raw gas got there through the FPR vacuum line.

Originally Posted by mike100

Poor man's leakdown test: What is the compression on one crank compared to other cylinders?

Yes.....I would be more suspect of the uneven compression. Blue or Black smoke for example.....burning oil or gas??

You say gray/blackish exhaust??

[XfireZ51]

Originally Posted by Dynomite

...
Yes.....I would be more suspect of the uneven compression. Blue or Black smoke for example.....burning oil or gas??

You say gray/blackish exhaust??

I do get a gray/blackish exhaust coming out when I jump on the throttle that appears to clear out. However, no such indication at startup or steady cruise.
I'm leaning a bit more towards out of phase cams on the driver's side. That side of the motor exhibits noticeably lower compression #s than the passenger side although all with the exception of #3 appear to be within the 10% tolerance level.