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Mr9146's Avatar
 
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STOP!

The only things you need to buy are a little spec book and a fuel pressure gauge so you can check your fuel pressures. You can diagnose and repair 99% of CIS problems with a good fuel pressure gauge, a test light, and a can of carb spray.

If you don't know your control pressure when cold or hot then you don't know anything about how the car is running. Don't worry about air leaks or any extraneous nonsense until after you know your fuel pressures.

YOU HAVE TO START THERE or you're just pissin' in the wind.

Hook up pressure gauge, disconnect power to WUR, check cold pressure. The spec is in your spec book.

Then hook up the plug to the WUR and WATCH the gauge ... it'll move fairly quickly. When it stops moving, that's your warm control pressure. The spec is in your spec book.

Then, use the pressure gauge to check your system pressure. Again, the spec is in the spec book.

Once you have this info THEN you can start messing with everything else.

You don't need a bunch of equipment to diagnose these cars. You need a spec book, a pressure gauge, patience, and a basic understanding of how the system works.


Last edited by Mr9146; 06-24-2016 at 07:03 AM..
Old 06-24-2016, 06:59 AM
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Thanks Marco.....I'm on it
Old 06-24-2016, 04:35 PM
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Ok
Got my fuel pressure test kit and hooked it up between the Fuel head and the WUR.
With the ball valve closed (System pressure check) 7.3 bar. good
Open ball valve to check cold pressure..way high..5 bar then climbed up to 7.3.
performed test without WUR plugged in 3 times. Same result. Bad WUR ???
Is there any other scenario that would create this result.
Turned off pumps and pressure went down to 3 bar and stayed there for 5 min and then very slowly started to lower.
Any input would be greatly appreciated.
Thanks, Mark
Old 07-04-2016, 02:33 PM
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forgot to mention I have a andial fuel enrichment system hooked up
Old 07-04-2016, 02:41 PM
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Did you have the motor out recently? Is the return line free of obstruction and/or kinks? I've seen an SC fuel pressure go haywire when the return line was pinched during a motor/trans install.

The Andial boost enrichment should only come into play when the car is under load and boosting.
Old 07-04-2016, 03:19 PM
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Quote:
Originally Posted by mas88s View Post
Ok
Got my fuel pressure test kit and hooked it up between the Fuel head and the WUR.
With the ball valve closed (System pressure check) 7.3 bar. good
Open ball valve to check cold pressure..way high..5 bar then climbed up to 7.3.
performed test without WUR plugged in 3 times. Same result. Bad WUR ???
Is there any other scenario that would create this result.
Turned off pumps and pressure went down to 3 bar and stayed there for 5 min and then very slowly started to lower.
Any input would be greatly appreciated.
Thanks, Mark
Just my story, BUTT... When I first got my car it was really eye watering rich. First time with the gauges showed 5.6 bar system and cold pressure. Most said it would not run like this but it did. What I found: the needle valve was missing from the fuel pressure regulator and the spring was stretched to compensate, also the fuel mixture screw was turned all the way rich. A new FPR and mixture adj helped followed by a BL WUR and new fuel pump (it had low volume) all is good now. Just sayin' you never know what problems a PO might do to fix a simple problem. I have the innovate LM2, an in dash a/f gauge, fuel pressure gauges in dash and on the wur to keep up with this system. Good Luck!
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1981 SC Steel Widebody, DP Lid, 930/51 to 3.2l, K27 7006 Turbo, DOD, P&P Twin Plug heads, Twinfire Ignition, Ruf Intercooler, Powerhaus headers, Zork, CIS Euro FD, 009 injectors, 044 pump, BLwur, 930 4 sp LSD, Mocal 44 w/fan, LM2, Brembo, Retroair, Euromeisters
2003 BMW Z4 Daily Driver & Autocross car. Sold
Old 07-05-2016, 04:26 AM
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Thanks for the replies.....
After sleeping on it I went back to check on the fuel pressure gauge (new) and found that the quick disconnect couplings are sh**...Thank you Harbor Freight
After correcting and re-testing
System pressure 7.3 bar
CCP 3.1 bar
WCP 4.1 bar
The only pressure thats off seems to be the CCP but only by 1/2 bar. Is that enough to screw things up ?
When I was performing the test and waiting for the WUR to warm up the yellow relay started to go crazy on-off flickering in conjunction with the fuel head buzzing ???
Some sort of over pressure release??
Any body ever heard of that ?
Old 07-05-2016, 08:10 AM
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The yellow relay shuts down the fuel pumps if overboost is detected. At idle, it should not be doing that, and I would think you have poor connectivity at the pins. Very common problem. Pull it out, clean it and many (including myself) have used a razor blade to slightly spread out the male pins to make better connection.

No idea if this is related to your issue, but it certainly has to be addressed.
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Old 07-05-2016, 08:30 AM
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Hi Jeff,
This happened when I was doing a fuel pressure check.
Engine off, fuel pumps running.
I think the yellow relay was doing its job...???
Old 07-05-2016, 05:32 PM
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The overboost relay doesn't measure fuel pressure, it measures boost. In fact, it doesn't even measure boost, the boost sensor does. When the sensor detects overboost, it grounds out, which signals the relay to open, which cuts off power to the fuel pumps. Unless there is something else to it that I do not know about (many here have far more knowledge than I do), the relay should never cut out while the motor is off, even if the fuel pumps are on. To my knowledge, fuel pressure has nothing to do with whether it cuts out or not.
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Old 07-05-2016, 05:44 PM
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It's best to test fuel pressures with the car running.

Also, if your fuel pumps are running with the key in the ON position and the motor stopped, the frequency valve is buzzing away and your sensor plate plug is disconnected. Not a big deal, just an FYI.

Check the fuel pressures with the car running...
Old 07-05-2016, 06:31 PM
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Just to add some more info to what Jeff and Marco said about the fuel pumps running and the yellow relay - that relay also plays a role in preventing the fuel pumps from running if air is not being drawn over the fuel head, air metering disc. If the fuel head safety switch is plugged in and working (passes an "open/closed" continuity test - switch is activated by the position of the air meter arm), yet the pumps run with the key, then that part of the yellow relay is not working or the pin associated with that function is not making sufficient contact in the socket.

Based on what you describe in post #27, that's likely what you have going on, mas.

Last edited by Rawknees'Turbo; 07-05-2016 at 08:26 PM..
Old 07-05-2016, 08:24 PM
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Quote:
Originally Posted by Hot Euro View Post
Just my story, BUTT...
You Lubbock TexASS folks are my kind of peoples!

PS - is your pimpin' a/c still pumpin' out the frosty air (saw how you posted your build thread in the "Best DIY accomplishments" sticky thread in the 911 forum - man that was a lot of fun helping from afar and your results sure were good)?!

Last edited by Rawknees'Turbo; 07-05-2016 at 11:55 PM..
Old 07-05-2016, 11:52 PM
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Quote:
Originally Posted by Rawknees'Turbo View Post
You Lubbock TexASS folks are my kind of peoples!

PS - is your pimpin' a/c still pumpin' out the frosty air (saw how you posted your build thread in the "Best DIY accomplishments" sticky thread in the 911 forum - man that was a lot of fun helping from afar and your results sure were good)?!
Still have blue knees every time I turn it on! Couldn't have done it without you ... and Jim Fairman, Thanks!
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1981 SC Steel Widebody, DP Lid, 930/51 to 3.2l, K27 7006 Turbo, DOD, P&P Twin Plug heads, Twinfire Ignition, Ruf Intercooler, Powerhaus headers, Zork, CIS Euro FD, 009 injectors, 044 pump, BLwur, 930 4 sp LSD, Mocal 44 w/fan, LM2, Brembo, Retroair, Euromeisters
2003 BMW Z4 Daily Driver & Autocross car. Sold
Old 07-06-2016, 04:21 AM
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Quote:
Originally Posted by mas88s View Post
Thanks for the replies.....
After sleeping on it I went back to check on the fuel pressure gauge (new) and found that the quick disconnect couplings are sh**...Thank you Harbor Freight
After correcting and re-testing
System pressure 7.3 bar
CCP 3.1 bar
WCP 4.1 bar
The only pressure thats off seems to be the CCP but only by 1/2 bar. Is that enough to screw things up ?
When I was performing the test and waiting for the WUR to warm up the yellow relay started to go crazy on-off flickering in conjunction with the fuel head buzzing ???
Some sort of over pressure release??
Any body ever heard of that ?
The harbor freight pressure tester works great, but you need to remove all the schrader valves from the couplings... They just unscrew. Once removed, pressures are very accurate...

If you left the schrader valves in, your readings are likley way off...
Old 07-06-2016, 05:03 AM
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Quote:
Originally Posted by Hot Euro View Post
Still have blue knees every time I turn it on! Couldn't have done it without you ... and Jim Fairman, Thanks!
Blue knees in Texass is a sure sign of success right thar!
Old 07-07-2016, 11:50 AM
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Schrader valves removed and gauge works great.
Who knew?
Performed test 3 times on 3 different days and all values are just about dead on.
ccp 2.5 wcp 3.7 system pressure 105 psi
After performing these tests car runs great for about 2 days. ???
The only thing I touch is the input line on the WUR and the power supply plug.
I disconnected the o2 sensor...no change
\If I run the car every day, no issues. It acts up when it sits.
Are there any fuel issues after the wur and should I go after the ignition??
Old 07-13-2016, 02:01 PM
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Quote:
Originally Posted by mas88s View Post
Schrader valves removed and gauge works great.
Who knew?
Performed test 3 times on 3 different days and all values are just about dead on.
ccp 2.5 wcp 3.7 system pressure 105 psi
After performing these tests car runs great for about 2 days. ???
The only thing I touch is the input line on the WUR and the power supply plug.
I disconnected the o2 sensor...no change
\If I run the car every day, no issues. It acts up when it sits.
Are there any fuel issues after the wur and should I go after the ignition??
The car doesn't have the low rpm popping problem if you use it every day? And after you mess with the WUR line to the fuel head the car runs well for 2 days and then starts acting up?

Am I understanding this correctly?
Old 07-13-2016, 04:45 PM
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Yes
I didn't even want it post this because I think its coincidental.
First time I did the fuel pressure check...engine off...when I put it back together it started right up with the high idle and then kicked down, ran perfect.
Next day no problem.
Following day, barely ran, if I try to accelerate, just popping, but if I let it idle for 5min I can slowly work up rpm's . After 10in or so, I can drive it but still has hesitation below 3000rpm.
So following day, I started it, same ****..immediately shut t off and took fuel pressure test.
Engine running.
All specs within range.
put it back together...just the fuel line from WUR, so not to disturb anything else.
Problem gone....grrrr
Next day, no problem
Following day , same ****..low popping, no rpm's
fuel pressure within spec
It feels electrical but I'm just guessing. Almost like distributor is in wrong place.
Ignition module? I had t rebuilt last year but you never know.
Old 07-14-2016, 05:35 AM
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Are you unplugging and plugging in the WUR each time you do the test?

Old 07-14-2016, 06:51 AM
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