You should test the BM strip. It could just be that everything is out of adjustment. It takes some talent though to get it adjusted right. Might just be better off buying a rebuild.

tirwin,

Sounds like your WUR is bad. A stuck or low control pressure would result in a too rich mixture when warm, not coughing and stalling when cold running. The symptoms would be fouled plugs, lousy fuel mileage and fuel in the oil. Perhaps the basic mixture adjustment has been leaned out to compensate.

Agree that you may have a problem with the bimetallic heating element, but it doesn't seem to account for your symptoms. Your numbers indicate the wur is functioning properly for a cold start and initial cold running. Even if the element has failed, the heat from a running engine would cause the bimetallic arm to adjust the pressure--unless the arm is faulty. You might do a follow up test by actually running the engine until it fully warm and then take a warm control reading. If it's still low, the arm is faulty as well.

A quick question about your test before you pursue any repairs: Did you check to see if there was current to the plug for the wur before doing the warm control test, or did you just plug in the connector? The heating element is the primary cause of failure in the wur but you should double check to see if it is actually faulty.

Back to your initial problem. I agree with Paul--it still sounds like a too lean mixture, though you still may have a problem with the wur. Could be air leaks or a leaned out mixture adjustment via the screw on the FD.

Just had a simular problem... Adjusted the FD, now it will start alot better. I still have a small air leak somewhere, but it sure helped the problem.

Hmmm... But the mixture has been adjusted to run rich. I am now confused. :confused: What am I missing?

The engine was not running when I performed the warm control pressure test, so as I understand it, the electrical connection to the WUR should be heating the bi-metallic strip in the WUR. Since there was no change in the pressure once I connected the electrical, I can only assume that:

(1) the WUR is not getting power, or
(2) the WUR is getting power but the bi-metallic strip is not heating properly

So, you are correct... I need to verify that the WUR is getting power before I assume the WUR is faulty.

Here is a link to a video on Youtube I used as a reference:

CIS Fuel Pressure Test - warm pressure test

My understanding is that at cold start, the arm of the BM strip pulls the diaphragm away from the valve which (a) increases fuel return to the tank and (b) reduces control pressure. When the BM strip heats up, it closes the valve which increases control pressure and decreases the amount of fuel return to the tank.

Under normal conditions (ie, not this bypass-starting-the-engine-but-run-the-fuel-pump-anyway test), it seems logical that the heat from the engine would cause the BM strip to warm and close.

This would seem to indicate that the strip works and explains why the car stars fine after the engine is already warm.

In my case, the control pressure never increased once the electrical connection to the WUR was made.

tirwin,

Did the PO say it was set rich because of the broken WUR ? Control pressure offsets the deflection of the air flow plate and low control pressure increases the amount of fuel to the injectors. When cold the pressure is low and you get a higher plate and more fuel for warm up. Your pressure never increases and it should be running too rich when warm as a result. Your cold running problem is probably caused by something else and after your replace the WUR, I would be checking the mixture at hot idle in case it was adjusted to compensate.

tirwin,

If the engine was not hot for the warm control pressure test, you need to drive the car several miles and check the pressure after the engine temperature has risen.

Previous owner didn't suspect the WUR to be bad.

If the BM strip has completely failed, then control pressure should never, ever increase, right?

But, what if the strip is just not getting power? In that case, it may be that the strip is still capable of doing it's job, it's just that it's not because it's not getting any current to warm it up. In that case, it would seem that heat from the engine would warm the BM strip and cause it to close the valve. In that case, I should see control pressure increase to a normal level.

If the control pressure is at a normal level with a warm engine, then the mixture should be at the "normal" setting (normal is of course relative, but let's not change any other variables at this point). If the control pressure never increases to a normal level with a warm engine, then what you are saying about that the mixture being too rich makes sense.

Sounds like I need to do two things: (1) check to make sure WUR is getting power and (2) run the engine for a little while and check the control pressure again to see if it's in the normal range.

Sorry if I'm being a bit thick but I do feel like I'm making progress. I'm still trying to sort this all out in my head and understand things. Hopefully it will help someone else. :D

The WUR is not getting power. The key must be on for the CIS daisy chain to light up on cold start. Your car would not run anywhere near normal at 2.5bar pressure with a warm engine.
Re-check the WUR electrical plug with the key on.
As the manual states, many things can cause the symptoms you are experiencing; faulty injectors, leaky CSI, intake leaks, sticky WUR b/m strip, and bad karma from the PO. You are improving your karma by working on the car yourself. ;)

Did you try removing the oil cap? It should drop your RPM's to about 750 frm 900.
If it makes little change I would start looking for air leaks.
Don't know if this was already suggested.

RarlyL8,

The key was on. I ran the test using the bypass jumper as described in the Probst book and the Haynes manual.

So, just to be clear, the ignition was ON with the fuel pump running but the engine was not running. The link to the video on Youtube in one of my earlier posts clearly shows the control pressure increasing when the WUR is plugged in w/o the engine running. When running the same procedure, my control pressure did not increase.

Two things - put an ohm meter across the two pins on the WUR electrical plug. If you get no circuit you have a broken heater wire in the WUR finger. It is supposed to heat and bend against a spring and close up the diaphragm = increased pressure.
Second, get the car running, pull the WUR plug and put a volt meter across the wire PLUG terminals - you should register 12-13 v.
alan

Alan,

I tested the WUR with an ohmmeter and the circuit is good.

If I understand things correctly, if the fuel pump is running the circuit to the WUR should be energized. Right?

If you have resistance across the WUR pins then it should work as long as it is getting power.
I cant remember how the power circuit goes - but you can pull the plug while engine running, and you should get a 12v feed to the WUR wire. Just checked - your WUR feeds off terminal 30 off your fuel pump relay - so yes , if the pump goes, so does the WUR - Unless you have a bad connection on the way - there are two connectors en route.
Another option I have used is to hook a separate 12v battery source to the WUR terminals with a couple of alligator clips, turn key on and get pump running and watch the Control pressures. This likely is not going to fix your problem of engine dieing after start up, but if the CP is not rising within 5 mins you have an issue that needs fixing.
My outside guess is a leaness or airleak. Your Cold Pressure looks OK - so probably not lean as per mixture, but maybe via airleak. If your Warm pressure is same as Cold Pressure, maybe the airleak was compensating for an otherwise over rich mixture?
just guessing. But get the WUR functioning right first.
Alan

i think what happens when WUR's go bad is the car owner (or PO) adjusts the mixture and idle for a good warm running car, lives with the cold problems and passes the problem on or never realize they covered up the real problem.

first 2 steps in working on CIS,
fix air leaks then check fuel pressures before making any adjustments.

fix the WUR, then go from there.
dont waste your time trying to adjust it unless you can fix either the bi-metal strip or the heating element or what ever is wrong. (buy a new one, your headache will be short lived)

If in doubt of the procedure or how your car is wired simply plug the gage into the fuel system and turn the car on. Watch/time the pressure increase from cold to warm.
The pressure must be increasing or the car wouldn't run anywhere near normal. Gas fumes would water the eyes.
If after all this the WUR is off spec give me a holler and I'll see if I have one in stock.

http://forums.pelicanparts.com/support/smileys/wat5.gif

Well, I feel stupid.

I tested the WUR electrical connection today. It was fine. Scratched my head for a minute. I was expecting to see a dead circuit. So I plugged it back into the WUR. In a few seconds the control pressure started climbing! It reached 3.5 bar in just about 20 seconds and maxed out at that point. Grrrrrrr. Maybe I didn't connect the plug far enough the other day.

SO, it seems that WUR is fine after all and all CIS pressures are in spec.

Guess I'm on to hunting vacuum leaks?

Wur......
 

There's nothing wrong with your WUR!!!!
1). The control pressure won't change or increase if there was no power to it.
2). WUR gets power at the same time as the FP.
3). You have unmetered air in your system.

It takes only a few minutes to set-up the test and 10 seconds later you're done. Avoid the guesswork and you'll find this air/vacuum leak/s in your system. All you need is a continuous supply of low air pressure between 5 - 10 psi. And PRESTO!!!! They will be right in front of your nose where you least unexpected to find. There are too many possible sources of air leaks in a CIS and some people get lucky by using carb cleaner to find them. But you cannot rely on luck all the time. The test will tell you whether it is leaking or not. No if's or but's.

Tony

We've all been there and done that.
I pulled an engine/g/box once, and stripped the gearbox right down to find why I had lost two gears. After no luck in the g/box and reassembling engine (g/box integral in engine), I found a stone in the linkage tray.
You have a way to go yet to catch up.
Vacuum leaks would be a good follow up - as previously suggested - run engine and spray hydrocarbon around all joints, rubber intake runners etc - if the engine note changes try and locate source of intake.
Alan