New '72 Tii engine running problems

[Stein-man]

GWB -

True confessions.  I took off the throttle body yesterday to have a heart-to-heart on the bench.  I also removed the black runner to its left.  One o-ring never got put on.  It *might* have mad a difference.  More working today!

 

Phil -

 

[gwb72tii]

hope that's the issue stein-man. I wonder how many other runners are missing 0-rings?

 

BTW years ago my son and I tried and failed to find a '72 Golf tii. We found the Colorado one I own now but your car brings back great memories.

Edited May 25, 2021 by gwb72tii

[Solarphil]

6 hours ago, Stein-man said:

GWB -

True confessions....One o-ring never got put on.  It *might* have mad a difference. 

 

Phil -

 

Chuckle...I think we’ve all had a moment like that, although maybe not all are honest enough to admit it.  But yeah, I guess that could throw off the mix ? 

Glad you found it before pulling out all your hair, or messing with all your settings.  I did have a case once where I was chasing a problem and got my settings so out of whack the car was nigh undriveable. I got so frustrated I had to park the car, and a short walk-about turned into a longer than expected dormant period. When I finally turned my attention back, I started with setting everything back to a factory baseline, then proceeding from there. I don’t know what made the biggest difference, resetting the car or resetting my brain, but I had messed so much with the settings chasing some ghost or another, I was really lost.  After the reset, it was pretty quick to find the fun the car is capable of.

 

Enjoy

Another Phil

[Stein-man]

Phil and GWB -

I have been focusing on the WUR.  I had sent the pump out for calibration and cleaning at H&R, who does lots of 230/280SL K-fisch pumps.  I *presume* they as least looked over the WUR.  I took off the throttle body and unhooked the plenum end of the air enrichment hose.  I sucked on it, and when cold, air does indeed flow through it.  With a screwdriver, I raised up the preheater to operating height, while flowing air through the WUR.  It does indeed stop air from flowing when hot.  

Since the motor is a 2200cc,, I decided that it needed more enrichment than called for in the factory manual.  So, I gradually screwed down the washer/nut and tried to start the car.  Same as before - starts great with the 5th injector, then dies after 1 second.  So I went the other way.  I set it to factory cold clearance, then put on another 1/2 turn of height on the nut, so the clearance is around 3mm cold.  Lo, and behold, it started and continued to run, though at 2800 rpms.  While running, I quickly backed off the throttle screw until it cleared the D-cam and backed off the mixture screw until it gave clearance.  I think I have to reduce *slowly* the amount of fuel that enters the engine from the WUR until the idle comes down a bit, then dial back the throttle stop and mixture screw.  

Now I have to also wait for a cord that I lost for my Zeitronix AFR meter getup.  (BTW, miserable customer service there)  After calling for two days and sending two emails, on my 12th call to them I got an unpleasant gent who ultimately guided me to the correct cord on their site).

[Stein-man]

When I start the Tii up, the 5th injector does it's job, and the car fires right up.  After about 1.5 seconds the 5th injector stops, and the car dies.  I have tweaked the WUR to run richer in steps - no change, and leaner in steps - no change.  Thusly, my problem doesn't lie in the WUR.  On a whim, I put some small visegrips on the return line - the car fired right up and continued to run, a condition I haven't been able to achieve in the two weeks that I have been wrestling with this.

On the back of the pump, where the return line goes to the tank, there is a fitting with a restrictor or check valve.  I popped out the microscopic snap ring and have extracted the guts.  I'm not sure that everything is in there, since I have never seen one before.  The spring goes back in first, followed by the "relief plug" for lack of a better word, then the microscopic snap ring. Am I missing anything?  Can I shim the spring to make it stronger against the relief plug?  What should I do with this latest data point? 

 

- Rob

[dlacey]

Sounds like the pressure relief valve is faulty and, therefore, you've got minimal fuel pressure. If this has been 'calibrated' by some 'specialist' then I would be asking for a refund.

[jimk]

19 hours ago, Stein-man said:

Since the motor is a 2200cc,,

Is system "trimmed" for this displacement?

[Stein-man]

Hi, Jim -

Not sure what "trimmed" means.  Can you speak further about this?  Thanks, Jim!

- Rob

[Stein-man]

Does anyone smarter than I am about this know if there is a part missing?  

 

 

Edited May 26, 2021 by Stein-man

[jgerock]

18 minutes ago, Stein-man said:

Does anyone smarter than I am about this know if there is a part missing?  

 

 

Mine has a washer inside  - I assume it is a shim to adjust the pressure relief setting.

[jimk]

1 hour ago, Stein-man said:

Not sure what "trimmed" means.  Can you speak further about this?

Sorry, I was not clear.  Trimming means adjusting the fueling for the larger displacement engine.  At idle, the fuel flow is very little and the A/F ratio sensitive.  Your pinching the return line is a signal that the pressure (as is) could use an increase.  At present, the pressure control may be controlling lower than spec, if not then more pressure than spec helps for the 2200 cc engine.  There may be issues with fueling at load/rpm if the mechanical system hasn't been set for increased air.

[PaulTWinterton]

[PaulTWinterton]

I've found that tuning the engine should be done when it's hot and the WUR is no longer involved.  That is confirmed by the tophat being disengaged from the enrichment lever and the airflow input on the top of the unit has stopped. 

 

You can then do all your linkage and tunacan adjustments to get your engine running smooth throughout the range with an idle at approx 900rpms.

 

Once the engine is cold again you can set up your WUR to work with the modified engine.  Adjustment of the tophat will give you the 2.6mm gap recommended in the manual to increase fuel enrichment and faster idle until the engine warms up.  That's the process,  but tophat adjustment will likely be different due to the 2200cc modified engine. 

[Son of Marty]

A fuel pressure reading would confirm this, it would also be good to see what the pressure is with the return blocked, but it's almost sure to be a weak spring in the return/regulator valve.

[Stein-man]

Jim K -

There is an enrichening getup on the pump for richer WOT fueling, otherwise nothing special for other rev ranges. 

 

Paul -

Oh, my, it was good to see your post.  All I need to know is how long that 36 psi spring is.  Let me know!  Also, thanks for the advice about tuning.  At this point, I can't even get the car to start and run. 

 

Marty -

I pinned my 40 psi gauge testing fuel pressure, so I don't know what it is.  Let's see, "manufacture" a shim for under the spring, or stretch is as Paul W says? 

 

- Rob