81 911 Cis-k Test Questions

[81white911]

Since I Cannot Start The Car, It Quit At Operating Temperature, And I Have Not Been Able To Restart Hot Or Cold. I Got The Jc Whitney Fuel Pressure Tester And Recorded The Following With The Ignition In The On Position, I Heard The Pump Running.

Wur 9.9 Ohms
Wur Connector 11.5 Volts

Valve On Tester Open Cold(75f) 70 Psi
Valve Closed 70 Psi

Immediately After Ignition Off And Valve Open Drops To 32 Psi Within A Minute Its Down To 22 And Holds For 10 Minutes, After 20 Minutes Down To 21 Psi.

I Tried To Measure The Fuel Flow By Relieving The Pressure Tester Button Into A Jar. I Got 250 Ml After 2 Minutes Whether The Valve Was Open Or Not On The Tester.

Should I Be Testing The Pressure As I Am Cranking The Engine?
Any Guesses As To Whats Wrong?

[mca]

I can't answer your questions ... so I am going to ask you some.

Did you jump the fuel pump relay to get the pump to run?

Turning the key shouldn't start the fuel pump.

Also, make sure that the WUR is unplugged (electrical connection) when you take your cold control pressure.

[dlagerstrom]

Weldome to the board. You need to post a pic of your ride!

There is a screen in the WUR that isn't that hard to get to. Pull the fuel connection and make sure the screen is clean. That can make a big difference in the CCP.

When did you last replace the fuel filter?

Before digging into troubleshooting the CIS, you really need to make sure everything else is running top notch. Since this is your first post, can you update us on what you have done as far as a basic tune-up goes? Is the car new to you?

Good luck.

[81white911]

The Pump Runs When The Ignition Is In The On Position, Maybe It Shouldnt But The Previous Owners Might Have Changed Something With The Alarm System, Who Knows, Ive Had It For 9 Years, Hasnt Run Well For At Least 4, The Plugs Are New, Distributor Cap Rotor Also, New Rubber Boot On The Injection Assembly, I Capped Off The Two Ports On The Back Of The Boot To Try To Eliminate Any Potential Vacuum Leaks. Also Replace The O2 Sensor. The Catylitic Converter Is Bypassed With A Pipe And It Passed The Ohio Epa Tailpipe Test 5 Years Ago When It Still Ran.

Is This Wur Screen On The Port That Is Piped To The Center Of The Fuel Distributor? How Do You Remove It?

[dlagerstrom]

I didn't remove it but blew it out with some carb cleaner. Be sure to wear your safety glasses.

The pump should not run with the ignition on but nothing else. Have you looked at the fuel pump relay? Is it standard? There is a switch on the air flow meter that should keep the fuel pump from running when the engine is not. There is a connector on the back of the AFM that handles this switch. Once, when I had been messing around with the CIS, I left this connector off and noticed right away as when I turned the ignition on, the pump ran. Maybe check to see if this connector is on properly. The connector is on the AFM toward the front of the car. You have to reach around behind to find it.

[ossiblue]

Originally Posted by 81white911

The Pump Runs When The Ignition Is In The On Position, Maybe It Shouldnt But The Previous Owners Might Have Changed Something With The Alarm System, Who Knows, Ive Had It For 9 Years, Hasnt Run Well For At Least 4, The Plugs Are New, Distributor Cap Rotor Also, New Rubber Boot On The Injection Assembly, I Capped Off The Two Ports On The Back Of The Boot To Try To Eliminate Any Potential Vacuum Leaks. Also Replace The O2 Sensor. The Catylitic Converter Is Bypassed With A Pipe And It Passed The Ohio Epa Tailpipe Test 5 Years Ago When It Still Ran.

Is This Wur Screen On The Port That Is Piped To The Center Of The Fuel Distributor? How Do You Remove It?

Yes, the screen is on the port you describe. Probably the easiest way to get to it is to remove the WUR, then you can pry out the screen and clean out the port.

Definitely follow the advice and disconnect the electrical connection when testing the WUR cold. Your ccp is too high and that may be accounting for the no start at cold (high pressure=lean fuel mixture) but you are on the right track in cleaning out the screen to relieve pressure.

Your ignition off pressures seem to be within specs.

Keep us posted.

[mca]

Also, remember that you need to interpret your test results according to the ambient temps when the test was performed.

The Bentley has a nice reference chart.

[Gunter]

No need to remove the WUR.
Just disconnect the line, use a light and look at the screen.
If it's dirty, you'll see it right away. Blow it out without removing.

That may not be your problem.

Your pump shouldn't run with ignition ON, someone changed something.
The Airflow Sensor Switch on the back of the Metering Body may be disconnected.
It's just a Ground, green color plug/switch.
It's hard to reach but a light and a mirror will tell you if the green plug is connected.

Buy the Bentley SC Repair Manual if you want to be serious about working on your SC.

[boyt911sc]

Originally Posted by 81white911

Since I Cannot Start The Car, It Quit At Operating Temperature, And I Have Not Been Able To Restart Hot Or Cold. I Got The Jc Whitney Fuel Pressure Tester And Recorded The Following With The Ignition In The On Position, I Heard The Pump Running.

Wur 9.9 Ohms
Wur Connector 11.5 Volts

Valve On Tester Open Cold(75f) 70 Psi
Valve Closed 70 Psi

Immediately After Ignition Off And Valve Open Drops To 32 Psi Within A Minute Its Down To 22 And Holds For 10 Minutes, After 20 Minutes Down To 21 Psi.

I Tried To Measure The Fuel Flow By Relieving The Pressure Tester Button Into A Jar. I Got 250 Ml After 2 Minutes Whether The Valve Was Open Or Not On The Tester.

Should I Be Testing The Pressure As I Am Cranking The Engine?
Any Guesses As To Whats Wrong?

81White911,

Gunter has given you a very good advise. I'm having a difficult time reading your post with all the CAPITAL letters you are using. Try to communicate emphasizing on the technical info you got rather than using those capital leters and you'll get better responses.

All SC's should not have the FP running when the ignition switch is turned to ON postion unless:
1). Terminal #85 (FP relay socket) is OPEN (no ground). This has to be corrected for safety reason.
2). The normally close (NC) 87a & 30 terminals of the FP relay is stucked CLOSE. A defective relay could cause this problem.
3). Or someone has altered the wiring set-up using a jumper wire.

At this point, I would assume that you are familiar with the procedures needed to manually run a FP without running the motor. If not, these are the basic steps you need to understand. Keep us posted.

Tony

[81white911]

ok guys, i have no idea why the fuel pump runs when the ignition is in the "on" position, i agree it could be a safety problem, but it has been that way since 1999 and is a side issue to my main problem.

I did find a two wire original connection hanging loose, it come up from behind the distributor and air cowling. It is red/white and brown wires, female, and the connectors look like trailer hitch connections (round).

I removed the wur electrical connections and got the same results 70 psi for control and primary pressure.

I blasted the port where this screen is with carb cleaner and my favorite PB Nut blaster. The control pressure dropped to 60 psi and the primary stayed at 70 psi. the ambient temp is 75 F.

I'm letting it sit for awhile and soaking that screen with PB Nut Blaster.

Does anyone have thoughts about the fuel volume test? From what ive read i should get 1 liter in 30 seconds. I am relieving fuel from the pressure release button on the cis-k fuel pressure kit. Is this the correct way to do it.

Pictures later when i figure how to post them.

Thank you all for your great advice, the books are on order.

[mca]

I don't think you can measure fuel volume using the relief valve on the testing equipment. That is there to remove air from the testing gauges.

To measure volume, I would imagine that you would pull your injectors and place each in its own glass (something to catch the fuel) and run the pump for 30 seconds. Then measure the amount of fuel in the glasses.

After you allow fuel to flow from the distributor to the WUR, what is your pressure?

After you get that reading and reconnect your WUR, what is your pressure? This will change as the heating element in the WUR warms.

Also, are you getting any spark?

[boyt911sc]

Originally Posted by 81white911

ok guys, i have no idea why the fuel pump runs when the ignition is in the "on" position, i agree it could be a safety problem, but it has been that way since 1999 and is a side issue to my main problem.

I did find a two wire original connection hanging loose, it come up from behind the distributor and air cowling. It is red/white and brown wires, female, and the connectors look like trailer hitch connections (round).

I removed the wur electrical connections and got the same results 70 psi for control and primary pressure.


Does anyone have thoughts about the fuel volume test? From what ive read i should get 1 liter in 30 seconds. I am relieving fuel from the pressure release button on the cis-k fuel pressure kit. Is this the correct way to do it.

81white911,

When the control pressure and system pressures become the same in values or equal, the WUR is not allowing the fuel to pass through. Check the fuel flow of the return line of the WUR. This return line is connected to a T-connection of the main fuel return line from the fuel distributor and goes to the gas tank.

To measure the delivery flow rate of your FP, you could do it with FP mounted in the car or off the car. On car: Disconnect the fuel delivery line to fuel accumulator and run the FP. This is not easy to do alone (solo) unless you have the correct set-up and extra fuel line to collect the fuel. Off car: Simply remove the FP and bench test it but you need a special gas tank set-up to do this procedure. The on-car test is more convenient unless you have the hardware and set-up for a bench test.

Someone has suggested doing the flowrate measurement using the 6 injectors. This procedure will tell you the flow rate via the FD (fuel distributor) and the value of the flowrate obtained is no where close to the fuel pump delivery rate. WHY? A portion of fuel delivered by the FP is diverted back to the tank via the FD pressure release valve. Since a good FP can deliver excess fuel needed by a CIS, the excess fuel is directed back to the gas tank.

Any more questions? Just ask. Good luck.

Tony

[81white911]

Gunter you are the man, I soaked that screen on the wur for another 4 hours with PB Nut Blaster and then blew it off with a can of compressed air that you would use to clean a computer. The wur control pressure dropped to 30 psi and the primary stayed at 70 psi. Ambient air temperature still 75 F.

Boytsc , I plugged the wur connector in and the control pressure climbed steadily from 30 psi to 55 psi and stablized in about 60 seconds.

Boytsc, I understand what you explained about recirculation of fuel and the way i was trying to measure it.

Going to get a new fuel filter Wednesday after work and install before i try to fire it up.