dr bob

The pressure reading with the valve closed is system pressure. Valve open shows control pressure. Engine is full-rich with lowered control pressure. Warm-up regulator is bypassing full flow back the tank.

82EUROATM

so if I understand it correctly what controls the pressure on the return line is wur. I looked at it today and checked the oil and it’s full of gas where the oil is like water. I was told don’t start it until I change the oil. I crimped the rubber return line that had the injector and turned the pump on and only got 20 psi.
I can’t seem to find the correct wur unless I spend 500.00 I spoke to roger at 928rus and he’s trying to find one. Is there anyway you manipulate the one I have to work ?

jpitman2

Close, but not quite there. The system pressure is controlled by the valve in the FD. The control pressure is regulated by the WUR - low when cold, increasing to ~45psi when fully hot. The control pressure is fed to the FD to allow more fuel (low control) when cold(rich), and lean out the mixture as it warms by reducing the control piston stroke. Usual problem with WUR is that crud gets caught in the gauze filters and partially blocks the unit, producing high control, making the car hard to start cold, and severely reducing power when hot. With control up in the 50psi area mine would not get over 20mph, and then only slowly.
Your system of 68psi is in the ball park.
See if you can find Ben Watson book on Bosch injection, or I could send you the CIS section if you give me an email address - very good troubleshooting in the there. My copy was $15 , but now its at crazy prices.
jp 83 Euro S AT 57k

dr bob

After yesterday's exchange, I realized that you are flying pretty blind through all this. JP's recommendation on the Watson book is good. I also like the Probst book on CIS. Bought a used one recently on Amazon for cheap, on the way to helping a local '79 owner. Regardless, you'll want to study the book(s) before you go much further. Knowledge of function of the WUR and the effect of control pressure on mixture is absolutely essential.

As you move forward, you'll want to ventilate the intake and put new oil and filter in it before you start it. Between now and then, you'll be doing all your system and pressure testing with the engine off. Connect your battery maintainer at the battery, and use a switched jumper to bypass the fuel pump relay for any testing. Don't even try and start the engine before you see pressures that meet the WSM chart criteria. Ultimately you'll want to see the correct chart pressures with the modulating valve working, unless you can find the correct original WUR and the plumbing to bypass the modulating valve completely.

There may be, but it involves changing the bimetal strip and the spring. Mods would be done on a test fixture as described in post 23 above. I use a fuel-injection cleaner can as a source of cleaner and for primary pressure control, and could test a calibration against known WUR curves. You can make a similar fixture as I described, especially since the gauge plumbing fittings are already in your garage. You'll need a vacuum test pump, as the specs all include a specific test manifold vacuum. Getting the balance between the coil spring pressure and the thermo functions with the bimetallic spring is the challenge. Or send yours to be "rebuilt" to its own original specs, and get the rest of the system working.

For sure, don't go in bending and twisting pieces blindly, trying to chance on a result that might accidentally land on a result that sort of runs sometimes.


Read the books. It will save you a huge amount of additional frustration.


For those playing along at home, the Probst book includes a lot of info on Bosch injection from CIS through LHA and more. It's a casual cure for insomnia too.

82EUROATM

i ordered the Ben Watson book but it won’t be here till 5/22 and your right I paid 50.00 for a used book.
im getting fuel in the oil and have to change the oil.
why am I getting so much fuel in the cylinders and oil ?

82EUROATM

I changed the oil and filter and let it sit for a day or two.I’m waiting for the Ben Watson book to make it to my house. I’m getting 65psi cold with gauge closed and open is still zero I tried to start it and it ran for for about ten minutes and at first it idled high and then idled down but would stall after I give it gas. When it was running I pinched the rubber return line and the idle went up and went down when I let it go but it ran until I shut it off but still no psi. Your right With the analogy I’m flying blind with no lights in the dark LOL. Kind of curious as to why it idled up almost 500 rpm when I pinched the return line. I think the wur in the car works with the injector and the box in the fuse compartment when it was federalized. I think the car will only run correctly if get the 086 wur that belongs in the car with no injector. I’m in the process of getting a oscilloscope and a gas analyzer because there’s no way to dial anything in without them. The best thing about getting to where I am with the car is my wife coming outside in amazement when she heard the sound of it running for the first time. I think she’s getting shark fever.I appreciate everyone’s help and I am greatly thankful for all the time everyone has spent answering my questions.

dr bob

Re-read post 49, focusing on the part that sez to do all your testing with the fuel pump jumpered AND THE ENGINE OFF. Since you've run the engine with zero control pressure and therefore a more than full-rich mixture, best not to run the engine again until you can swap in fresh oil.

All that gas washes the oil off of cylinder walls, and you scuff pistons at best. Damages the iron coating on the piston skirts, scuffs the bores. Somewhere in the middle of this, the engine becomes a boat anchor. Save yourself from that. Unplug the starter or something.

82EUROATM

hi bob I was able to get the car to run after draining the oil and new filter the oil is nice and clean.
the car cold with car in the on position and the pump jumped I have a system pressure of 65 which is right on the money but the minute I open the gauge I get zero control pressure.I also have good rest pressure.The car will run for 10 minutes but start to run like crap and eventually die. While it’s running it has good throttle response but will die out. The plugs get black but not wet with gas like before.i can’t seem to find or locate a 086 wur which calls for my car. I purchased a Snap-On mt3000a which has a dwell / oscilloscope/ and all the goodies to get info.
I think I’m close but I can’t get past wur being bad or the FD

dr bob

I figured that disconnecting the starter would keep the engine from running while you sort the WUR. I figured wrong...


Something is holding the WUR open. You mentioned that you "rebuilt" it. What exactly did you do?


Reiterating: Don't Run The Engine Until You Get the WUR and Control Pressure Correct. Running it now buys you nothing, risks irreversible bore and piston damage in a hard-to-find engine. Did you get a chance to go through the Watson book? I shows you the internals of the WUR. Since you show zero control pressure, something is drastically amiss inside the WUR.

82EUROATM

Is it possible that the wur in the car is set up to run only with the frequency injector. I’m trying to find a wur 086 but it’s almost impossible to track one down I found one guy in the uk but he wants 2000 with is crazy

82EUROATM

I didn’t rebuild the wur i took it apart and cleaned out the screen and put it back Very carefully knowing that bimetal strip is very sensitive

82EUROATM

I did receive the Ben Watson book and agree that I can’t go forward until I get the wur in order

gbgastowers

Did you check here??

dr bob

The possibility exists that the frequency valve is actually set up to work like the KE-jet (no WUR used...), and the installed WUR is just a placeholder. All the control pressure management is done by the electrical box. To work, it would need to know coolant temperature and manifold pressure, plus the connection from a working oxygen sensor. Look at the connected sensors for the tan box, and see if there are manifold pressure (vacuum) and coolant temp sensors wired in. It would also need a key-on or fuel-pump-running input. Those connections would be a clue to whether the tan box is even able to do the calcs needed. Else, you are shopping for the original-to-the-car part number for a replacement WUR.

Received an Amazon link for an auto-ranging DMM that includes a duty-cycle measurement, around $30 IIRC. Have to go hunt it down if that interests you. I'm old-skul and use on ascilloscpope, mostly because I have one and need to justify the shelf space it pigs up in the years between uses. Else I'd spring for the meter and have it read to me.

82EUROATM

i just purchased a Snap-On mt3000a
machine that reads dwell / dutycycle and has a oscilloscope in it. I think I’m going to put frequency valve all back together and try and get reads to dial in the control box. I’m not sure exactly how to hook up the oscilloscope to the car. I have no manual