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 Those of you following the saga on “What did you do to your 2002 today?” know that Zouave has been undergoing an extensive refresh of what I hope will be his last major system for a good while: fuel delivery.  To baseline the discussion, below is a description of all the work I have done on the fuel delivery system (and the other 90% of fuel delivery issues, ie, the ignition).  I may have missed something, but as you’ll see I haven’t skimped.  

 

The problem we’re having at the moment is hopefully a “last mile” issue: dialing in fuel mixture.  But it has been very hard to do.  Needless to say, I have read both KF manuals (BMW NA and Hoffman) and more than a dozen posts on the topic, some several times, and spent hours with Stevenola bent over a hot motor (sounds worse than it was).   I’m a lot smarter about the KF system than I would otherwise be thanks ot all y’all.  Just not smart enough to know where to go next from here.  

 

 So I generally get how to tune the KF.  Unfortunately, no matter where I set the d-cam and how I twiddle the mixture screw, my idle moves around, my afr readings move around,  it all changes a bit between test runs and I’m not seeing the kind of consistency others seem to see between idle and WOT.  The car is only even remotely happy at rich rich settings, like idling at 10-10.5, WOT at 12.1-12.4, CO (if I believe my cheap cheesy metering device) around 5%; these are averages, as neither the WB gauge nor the Gunson’s Gastester often stays still.

 

And I am getting the same intermittent miss/stutter under load (different rpms at different d-cam settings) I had before all this work started.  Finally, my cold start (once the best part of the system) is fitful.  Car starts, then starves to death without pedal feathering.  

 

So notwithstanding all the work done, something ain’t right.  

 

This post is to solicit help covering the last mile.  Before worrying again about the fine details of tuning, I have one more mechanical mystery I need to understand better —  how the pressure regulator valve may be affecting all this. As noted below, while my fuel pressure is 29-32 lbs in front of the pump, it is literally 0 after the pump.  I have read a ton of threads, and I have read McCartney.  Only McCartney specifies a max flow through that valve, but even he doesn’t say what happens if you have too free flow through the valve.  Mine is obviously pretty free.  I would not have thought it possible to have 29 at the front and 0 at the back, but that’s consistently what I’m seeing.  I have avoided taking it apart up till now because I have fat fingers, and dread losing that damned spring.  

 

Can anyone explain how the free-flowing pressure reg valve may be contributing to the above conditions?

 

To recap the work done/other vital data:

 

Ignition side:

 

1. New 123 distributor

2. New Kingsborne wires

3. NGK 6s with few miles — plugs are all burning evenly

4. 123 advance curve:

CC83D94B-F17E-4B5B-8B6D-5647625722FA.jpeg

The slight uptick in the curve at 500-800 is to account for the drag of the a/c when it’s running.  Keeps the car from dying on a hot day (virtual decel valve!).

 

Fuel side:

1.  Fuel tank and pickup cleaned.  New intank screen.

2. New fuel hoses throughout.

3. 5 series fuel pump (existing) observed to sound normal

4. Soaked hard fuel line interior in carb cleaner for 3 days; blew out with cleaner and air; observed clean/clear

5. New inline Bosch filter

6. Soaked KF delivery valves in evaporust, followed by carb cleaner; clean with compressed air; observed to be springy

7.  Winterton-reconditioned injectors

8. New BMW injector lines

9. Observed clean banjo bolt filter screen; cleaned it anyway; new copper washers

10. Blew out pressure regulator valve with cleaner and compressed air

11. New linkages and springs, including new intermediate shaft.  All adjusted per KF manuals

12. Cap under throttle body to block fugitive airflow

13. Removed stock decel valve; plugged all vacuum points related to same, including throttle body-to-breather hose

14. Maintained manifold vacuum connection to 123 distributor; engine has excellent vacuum characteristics

14. New tuna can spring

15. Did pro forma ‘gas leak’ test per p. 17 of Kfisch manual — all flowing

16. Observed WUR to be closing off after warmup.  Though it only extends about 7.5mm, pinching air hose after warmup does not affect idle

17. Replaced thermo time switch; new Zeitschalter guts from Jsnpp; new wiring harness from Dave Wetzel; cold start injector works; not     leaking

18. Extensive testing for vacuum leaks with carb cleaner spray — none found.

19. Fuel pressure at front of KF: 29-32

20.  Fuel pressure at rear of KF (hose behind pressure regulator valve): 0 — that’s ZERO.   When I pull the hose at the firewall and crank the engine, I get plenty of fuel. 2-3 seconds of crank delivers nearl 1/4 cup of gasoline

 

 

Other vital data is compression/leakdown:

1. 150lbs/30%

2. 160lbs/15%

3. 160lbs/20%

4.160lbs/12%

The leakdown is all rings, which I attribute to the car having sat for most of the last 23 years.  Legend says that can be fixed on some cars with extended close-to-redline driving (what my friend Peter calls “drrriving ze shit out of it.”).  If I can ever string together 1000 good-running miles, I intend to test that proposition.

 

I believe the motor to be stock, and to be original except for a valve job done by the original owner (I am 3d owner, by all accounts). 

 

Just to get it out of the way: one mistake I made when pulling the system apart for refurb was not to note correctly where the d-cam was set relative to the hole.  

 

Did I mention Zouave has no rust?  This is a really nice car, if I could just get it to settle in.   Thoughts appreciated.

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I think that pressure regulator is doing what it should... its maintaining 29psi in the pump head and 'downstream' of the pressure regulator is the unrestricted return to the fuel tank - should be low pressure.

 

How is your linkage pivot? The pivot point for the intermediate shaft is in a cup on the back of the WUR... that cup should have a plastic liner sitting inside it (and a rubber cover outside) - these positively locate the end of that rod and prevent sidewards slop. sometimes the plastic liner is missing, that will screw up your synchronisation hysterically (meaning with some hysteresis).

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Thanks for both comments.  I may be making too much of the pressure regulator valve issue, but there is so little discussion of the effect if you exceed McCarthy’s notional maximum of 1000 ccs.  It makes sense to me that flow back to the tank should be under no pressure.  In fact, pressure would suggest blockage.  But the sad thing is that without that as a reason for my issues, I am really scratching my head.

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2 minutes ago, dlacey said:

With 12.4 at WOT, maybe it's just a little rich...try a hotter spark plug??

It’s a good point.  Do my compression/leakdown numbers suggest hotter plug?  Running a fresh red coil already, no resistance….

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I don't know about leakdown, but the compression figures seem quite normal. Agree some exercise may improve uniformity.

Given the very thorough service you've done of the injection system, I just felt that something on the ignition side might be the missing link.....

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Don’t bet against Stevenola.  He only appears to be a couch potato. He will soon offer a miraculous solution.  To be fair, his tuning got us as close as we have gotten to good running.  

 

Leakdown numbers are scary, but I am told that that is likely because the top sealing rings (and their opposing cylinder wall surfaces) on the original motors are prone to rusting when the motor’s not run for long periods.  That creates air gaps.  But I’m also told that they will self-hone and re-seal if driven wirklich hart.  Trying to get far enough along in this process to try that.

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13 minutes ago, PaulTWinterton said:

FWIW, Original red coil uses 1.8 resistor.   My modern one uses the external resistor as well.

Paul, ‘74s use a clear resistor wire, not a traditional resistor.  But the 123 allows you to dispense with resistors altogether and take advantage of the full power of the coil.  Not that I’m very sophisticated in this regard, but my understanding is that I’m getting very strong sparking power this way.  One reason I’m not sure a hotter plug would be beneficial (but welcome further guidance in this regard).

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I don't think leak down necessarily affects these performance anomalies.

 

Suggest smoothing out your advance around idle to see if that makes idle... smoother. Timing will affect AFR also.

 

Check your AFR gauge and perhaps look for an exhaust leak? 

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