CIS fuel pressue/WUR question

[supercarrera82]

I own a 1977 porsche 2.7 911s and ive read all of the how to for dummy write ups on CIS adjustment. The car has been sitting for a while and i have it running however it dies after a minute or two of starting it up. I recently bought the CIS fuel pressure gauge from harbor freight , while checking the bar i was getting a reading of approx. 4.5 to 5 bar with it closed however when I ran the gauge with the line open I was not getting a reading (Ive read it suppose to be around 1 bar), the gauge barely moved. Also I checked my WUR and the ohm's were reading approx 10.4 which is under its range. I replaced the WUR with a functioning one and it is still dying after a minute or two.The car has a new fuel pump, alternator, plugs, wires etc... What is my next course of action? I dont want to touch the CIS mixture with an allen wrench unless I have to. Thanks for your input

[timmy2]

Could be your return line to the fuel tank is blocked. Or the return line from the WUR is blocked. Or many other things.
You didn't say what the cold and warm running pressures are with the new WUR.
Need the numbers to be able to diagnose the problem.
Warm running pressure can be obtained without starting the car. The heater in it will get you there in 5 minutes.
What is the number on the WUR?

[supercarrera82]

I didnt think of the return line being blocked, good idea. The new WUR gave me the same 4.5 bar reading closed and no reading open. I will get the WUR number tomorrow along with the other numbers. Thanks for your input

[timmy2]

Take a picture of how the gauge is set up as well.
It needs to be a "t" set up where only the WUR side of the gauge can be isolated.
Could be the gauge as well.

[don gilbert]

the return line on the middies usually is blocked where it enters the tank, a sharp bend there the does stop up, esp. if they have been sitting.

[boyt911sc]

Supercarrera,

Find or borrow a good fuel injection pressure gauge kit for CIS. These HF pressure gauges are unreliable. I have several people I am assisting now to get their engines started using the HF pressure gauge kit, we are no closer to finding the control fuel pressures after weeks of back and forth emails. The time and effort you have spent troubleshooting your CIS problem/s could be minimized by using a good and reliable set. Keep us posted.

Tony

[boyt911sc]

Originally Posted by timmy2

Could be your return line to the fuel tank is blocked. Or the return line from the WUR is blocked. Or many other things.
You didn't say what the cold and warm running pressures are with the new WUR.
Need the numbers to be able to diagnose the problem.
Warm running pressure can be obtained without starting the car. The heater in it will get you there in 5 minutes.
What is the number on the WUR?

Dennis,

It could not be the return line!!!!!! Why? If the return line is blocked, the more pressure reading you'll have on the gauge. There are several possible scenarios I could imagine that could have similar results. First, is the set-up, second is the reliability of the tool used, the WUR is questionable, etc. The way I would troubleshoot this problem is to isolate and test each section of the system. But without using a good working pressure gauge kit, it would involve a lot of unpredictable test results.

Tony

[timmy2]

Tony, I agree with the gauge probably being a big part the problem. (Or the set up)
That was the reason for the second post after I re-read that he was using a HF gauge.

[E Sully]

From the fact the gage reads no pressure, I would think the gage is not properly set between the fuel distributor and the WUR.

[T77911S]

Originally Posted by E Sully

From the fact the gage reads no pressure, I would think the gage is not properly set between the fuel distributor and the WUR.

thats what i was thinking.
a blocked return would read max preassure all the time.

when i get readings or results that are off the chart, i go back and look at what "I" am doing wrong

[L8apex32]

It sounds like we have some missing info. How do you know the 2nd WUR is good?

The only way to know for sure is to test it with a pressure gauge.

Since the pressure gauge shows the same "bad" reading for both WURs, either you have two bad WURs or the CIS gauge isn't reliable. If the CIS gauge is not reliable you don't know, really, if either WUR is working correctly.

I hope this helps.

[boyt911sc]

Originally Posted by supercarrera82

I own a 1977 porsche 2.7 911s and ive read all of the how to for dummy write ups on CIS adjustment. The car has been sitting for a while and i have it running however it dies after a minute or two of starting it up. I recently bought the CIS fuel pressure gauge from harbor freight , while checking the bar i was getting a reading of approx. 4.5 to 5 bar with it closed however when I ran the gauge with the line open I was not getting a reading (Ive read it suppose to be around 1 bar), the gauge barely moved. Also I checked my WUR and the ohm's were reading approx 10.4 which is under its range. I replaced the WUR with a functioning one and it is still dying after a minute or two.The car has a new fuel pump, alternator, plugs, wires etc... What is my next course of action? I dont want to touch the CIS mixture with an allen wrench unless I have to. Thanks for your input

Supercarrera82,

If you are still struggling to diagnose your CIS problem and unsure about your WUR's, I'll help you with that. This is what I've been doing the last 2 days:



These are WUR's from fellow PP members being tested and calibrated. I could do a few more before switching to FD. BTW, the test is FREE and you pay the round trip shipping. Most of the time, they are good and need only some TLC.

Tony

[supercarrera82]

Attached below is my gauge setup , the #17 connection is on the fuel distributor and #21 is on the WUR connection off the HF kit. Let me know if anything looks wrong.

Also the WUR # on my 77 sc is 0458140 .

Thanks again for all your input !!

[timmy2]

In your gauge setup the isolating valve is on the wrong side. It should be on the WUR side not the fuel distributor side.
Reverse it and you may see a change if the gauge is accurate.


Sent from my iPhone using Tapatalk

[supercarrera82]

Duhhh...well i feel like an idiot

I will try it today when I am home, once again thanks for all your help

[T77911S]

it happens. just think about what you are measuring.
the fuel comes out of the top of the FD then goes to the WUR. with it connected like you had it, the switch isolates the gauge from the pressure out of the FD. with the valve between the gauge and WUR, now all the pressure will be felt at the gauge.


i also dont think you have the correct WUR for your car. it should end it 033. a 045 would work.

[boyt911sc]

The Bosch WUR has 0-438-140-XYZ identification format. The last 3 digits (XYZ) would identify your specific WUR. Clean and wire brush the top of the WUR to show the last 3 digits (stamped) on it. Keep us posted.

Tony

[RDM]

Originally Posted by timmy2

Could be the gauge as well.

I had a HF gauge that worked 1 1/2 times. This is a serious possibility. I reconsidered and bought one much like our host sells. Deming had something to say about this...

[T77911S]

this is the one i use. $120

Amazon.com: Tool Aid 33865 C.I.S. K-Jetronic Fuel Injection Tester with Case: Home Improvement

i like the looks of the one the OP has. nice big gauge, like the one my friend has.

you still need another adapter for the one like mine. i had an old WUR i that i pulled the adpater off of that to use.

[heliolps2]

Also check your fuel tank, give it a knock and see if its empty, it happened to me once, my gas gauge stopped at 1/4 , do have a AFR gauge ? tio check if your running to lean or rich ...