WTH -- Odd Pressure Readings???

[Ron]

First some background:
BAE turbo Car (boost OK).
Started and idled OK, hot or cold.
Would not rev over 4000 RPM (neutral).
Accelerated OK, gradually or full throttle, from a stand still up to ~3000, then loss of power -- only symptom was the deep throat sound as if running out fuel but no bronking if throttle held steady at any position).

=======

Primary pressure OK. Control Pressure high when dead cold (54psi then 72psi within 15 seconds).

Replaced the CPR/WUR (1st) => Pressures to specs at all temps.
No significant improvement in rev or performance.

Suspected FD. Placed injectors in separate containers -- delivered ~6oz in 1 minute, ~equal.

Replaced FD => Revs 5000 RPM max (neutral), no significant change in performance.

Replaced CPR/WUR (2nd) => Primary pressure 100. Control Pressure 100 psi.???

Suspected gauge- Swapped back to CPR/WUR(1st), pressures OK.
Blew out return line w/ 120psi air. Line was clean.
Swapped back to CPR/WUR(2nd) => Primary pressure 100psi. Control Pressure 100 psi cold.

What am I missing??? How is it possible for the primary pressure to be 72psi with 2 CPR/WURs and changing NOTHING but swapping for yet another CPR/WUR change the Primary Pressure, much less raise it over the 72psi???
I have always understood that the PPR sets the system pressure (72psi) making it impossible for either pressure to ever be higher as long as the pump is not changed and the return line is clear???

I don't think this has anything to do with the performance problem, necessarily, but WTH?
Any thoughts appreciated!

[David T]

If it stumbles at high revs it can be a couple of things.
Fuel delivery (not enough at high flows)
Air blockage (dirty filter)
Plugged cat
My personal favorite, high voltage breakdown in the secondary ignition circuit. (bad plugs, cap, rotor, coil, wires).
Because it is a turbo car you can also be leaning out because of air leaks (false air) with all of that extra induction plumbing.
Other less likely causes include valves needing adjustment, low compression because of a cracked piston, etc. Maybe start with a compression test and read the spark plugs. That will tell you the condition of the mechanicals and if you are running rich or lean.
David Teitelbaum

[Ron]

It doesn't do what I would call stumble...it just runs out of power quickly but smoothly at ~3000, a lot like a governor kicking in. If I let off of the accelerator to say 2/3 to 3/4 it will pull fine, press it back down and all you get is the deep throat sound while pulling just the same (unlike when one is running out of fuel...I can hold it down anywhere higher and it will never change.

I thought 6oz in one minute with the plate down was the norm?
I am going to do the test again with a couple of brand new injectors to compare all with...

Tried another new filter...other was clean inside.

I will try dumping it before the cat for sure (but those pressures are bugging me to no end).

Plugs, cap, rotor, wires are new. I tried my D's coil - no change.
(fwiw- I tried another distributor before the pressure weirdness.)

Compression is very good (he had the bottom end beefed up for the turbo a short while before the problem presented itself).
(And I checked it anyway.)

New plugs looked good after running it around (as hard as I dare) 5 min and after 30 min.

Thanks for input!

P.S. any thoughts on the 100 psi pressure?

[Spittybug]

Sounds like insufficient advance. Is dizzy mechanical advance working smoothly? Advance should be ~ 33* at WOT, 3,000 RPM. As high as maybe 50* at cruise at 3,000 RPM.

[Bitsyncmaster]

100 PSI is no good. If the return line is clear then the PPR is broken or plugged. I think the 6 oz/min is about normal but a turbo may require more.

[Ron]

Sounds like insufficient advance. Is dizzy mechanical advance working smoothly? Advance should be ~ 33* at WOT, 3,000 RPM. As high as maybe 50* at cruise at 3,000 RPM.

The distributor was reworked to limit advance per the BAE installation instructions when the turbo was installed. Tripple checked.

100 PSI is no good. If the return line is clear then the PPR is broken or plugged. I think the 6 oz/min is about normal but a turbo may require more.

That's what is puzzling about it...the primary pressure is fine with all but one CPR...how could a CPR cause the primary pressure to go above 72 psi, or change it at all???
The CPR return line goes to the FD, so I thought it might be the passage in the FD, on the way to the port the frequency valve and line to the tank. So, I tried another FD -- SOS.


Yesterday, I removed the return line at the tank and put it in a jug and started it up...Got a little dripping at first... nothing. ???
Disconnected the FD end and manually blew it out with ease. ???
Inspected the PPR for debris etc, again...nothing.
Put the other CPR/WUR on...same as before, ~54psi then 72psi within 15 seconds, cold.

[David T]

I understand you replaced ignition parts and they are new. Just because they are new cannot rule them out as to being the cause. It sounds like an electrical problem because it is very repeatable. I would reinspect each part and verify it's condition and installation.
David Teitelbaum

[DMCMW Julee]

Ignition problems will not cause erratic/wrong fuel pressure readings.

Erratic/wrong fuel pressures will make the engine run poorly.

(Dave on julee's phone)

[Kukem]

Ignition problems will not cause erratic/wrong fuel pressure readings.

Erratic/wrong fuel pressures will make the engine run poorly.

(Dave on julee's phone)

The jig is up! Apparently it's been Julee all along giving out the technical information but just letting "Dave" post it. We're on to you... =P

(Sorry I couldn't help myself... back to the topic at hand)

[David T]

The jig is up! Apparently it's been Julee all along giving out the technical information but just letting "Dave" post it. We're on to you... =P

(Sorry I couldn't help myself... back to the topic at hand)

I understand where you are coming from but since the symptoms do match up with erratic fuel pressures, for the moment I am disregarding them as to the original problem, loss of power above 4,000 RPM's. If the fuel pressures were that bad you would be seeing other symptoms more indicative of a fuel system problem. At this point I am not convinced it is a fuel delivery problem and certainly not a CPR or PPR problem. I agree it is often hard to distinguish which system to blame, ignition or fuel. Right now my bet is on ignition. A 50/50 bet and I could be wrong. More troubleshooting and diagnosis will settle this but for now I would stay with ignition.
David Teitelbaum