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Let's think if there's really a need for the factory to post separate pressure numbers for the WUR and TPR.
You can check that the WUR is operating (as in progressively increasing pressure) by starting from dead cold with the TPR unplugged. Applying 12V to the WUR should make the control presure rise. Ok, the numbers won't match the factory because the TPR is unplugged. Next, get the TPR back in line. By moving the throttle, you should see pressure moving by about 1bar up and down. If there's no variation, then the TPR it's bad. If you see variation, then you can try to bring it to spec by adjusting the 5mm allen on the WUR bottom. With a WUR completely warmed up, this should affect the warm control pressure. My point is, you dont need separate pressure readings from WUR and TPR to make an educated guess about which one is failing, and since neither is rebuildable, it's enough. Separate tests would add complexity to the procedure and need more fittings. |
I'm 100% agree with your statement........
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Jim, We have nothing to disagree!!!! I was hoping you have some test under your sleeves that we don't know. Those numbers are available in the shop manual. I was not questioning or doubting the procedure. What I was looking was a simple test procedure to test or evaluate either the WUR or TPR. Thanks. Tony |
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Also, as an old carb guy I can see that the TPR functions like an accelerator pump and can be adjusted as such by feel or better yet a mobile CO tester to check for proper A/F ratio under quick engine load transitions. My first 74 had "S" cams but FD was from a base model. Flooring the throttle, from say, 2500 rpms in 2nd would cause a bog that had to be remedied by swinging TPR all the way to the rich side (forward toward front of car, IIRC). Flipping over the spare WUR I have shows stake marks in the aluminum similar to injector bosses, so I imagine it could be rebuilt at least once if a guy had a dremel. |
Ok, I wanted to report and update from work completed tonight.
I have replaced all the return lines in the engine bay save the one from the TPR to the 4-line junction. With my brothers help, we blew high pressure air through the return line that goes back to the tank and I feel confident that we do not have blockage there. After all of these replacements, I did a cold control pressure test again with the same results as previous - 72psi. I did try one other thing that I didn't try the other day, and that was lifting the throttle lever which produced a reading of 78psi. I did not take any further readings for system pressure. So where do we go from here? The only other thing I can think of that I didn't do tonight would be to take the line off the 4 way junction that returns to the tank and run it into a container instead. S> |
Go back and read post #52.........
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The blockage is still there and probably around the FD. Don't keep changing fuel lines to locate the culprit. You need a systematic approach to finding this nagging problem. Isolate and pin point where the restriction is occurring. Read post #52. Have you contacted Andy (Schumicat)? Tony |
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I've read #52. I have not contacted Schumicat, but I've read his thread multiple times (my return line from the FD was just a standard hose and clamp, it didn't have a screw on fitting like the one he's olding in his last post... is this just a difference between his SC and my 74?). I understand that there must still be a blockage, and I will pull the main line that goes back to the tank from the 4-way to see if I get any difference and let you all know what happens. While replacing the lines last night, I pulled the 4-way junction and confirmed that it was clear. What else around the FD are you thinking might be causing the blockage? Is there something outside of a return line that could be causing it? |
When you blew through the lines with air, were the lines connected all the way to the tank?
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| | v v 3 4 1<-- ====== __|__|__ ====== <--- 2 Hey, Ok, so in my world there are 4 return lines that all attach to the 4-way T: (1) Return line to the tank --> T (2) Return line from the FD --> T (3) Return line from the WUR --> T (4) Return line from the TPR --> T I broke #1 loose at the T and blew high-pressure air through all the way to the tank. I got good flow results there. There was a short rubber line going from the T to the hard return line that exits the engine bay for the tank return, which I replaced with new hose. I replaced #2 with new hose. I replaced #3 with new hose. I did not replace #4 because I could not easily reach where it connects to the TPR to remove it. I will try that at some point in the near future. I blew high pressure air through all 4 of the ports on the T and there is no restriction there. I'm planning on pulling #1 off and dumping that from the T to a container and testing to confirm the tank return is in fact not restricted. Outside of that, I don't know what to do next. |
Just out of curiosity what are you replacing these lines with, the proper coline lines on barbed fittings I hope? I say this as I made the mistake of replacing one with FLAPS available 1/4" rubber line when I first got my car and got a schooling on just how bad an idea that was.
been watching your thread about to go back and try and tackle continuing idle issues in my '75. |
Further testing
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Further suggestion - Remove the TCPR from the hookup temporarily. Hook up the gauge set to the FD at the WUR connection. Disconnect anything from the other end (the end that would normally go the WUR). Put the open end of the gauge set into a container to catch fuel, preferably a graduated container. Make sure the gauge valve is closed, and have a timer ready. Turn on the fuel pump, and verify you have 72 psi or so at the gauge. Fully open the valve and start the timer, letting it run for 30 seconds and close the valve. Measure the amount of fuel and report. No fuel = blockage in the FD. 160 to 240 ml/min flow rate = no problem here. Need to look somewhere else. |
Had a very few minutes today to run some further tests:
Jim, flow rate out of the FD was measured thusly: ~115ml --> 30 sec = 230ml/min (which is within the 160 - 240ml you mentioned) Fuel pressure with primary return line pulled off the return to the tank into a can: 72psi Fuel flow out of return line is good Fuel pressure with WUR return pulled off the t-block into a can: 72psi Fuel flow out of return line is non-existent So based on these observations, this is what I'm thinking: Return lines are clear and unobstructed WUR is either obstructed or out of adjustment and has the return closed completely off. Next steps? Pull the WUR apart and look inside? send the WUR out to be rebuilt? If so, who should I send it to for the rebuild? sobamaflyer, I used hose that came with the car that appear to not be cohline (there are no cohline markings on them). School me on the cohline, please... To be clear, these are just for the return lines in the engine bay. Thanks for all the help! Steve |
Test.......
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Steve, If there was no fuel coming out from the WUR outlet, that's the obstruction in the fuel flow return. Were both pressure readings of 72 psi. taken with the valve open? There should be continuous flow of fuel via the WUR and TPR when the FP is running. I had a chance to look at the fuel system for '74 CIS. So what is your system fuel pressure now? You have to run your test with theFD's, WUR's & TPR's return lines open to atmosphere and collect them in a suitable container. All three (3) fuel return lines should have fuel coming out while the FP is running. The TPR could be also contributing to the problem (?), we don't know until it is tested. Why? Assuming the the WUR's return line is 100% blocked, the TPR is always open (theoretically) and would result into slight reduction in the pressure reading for the control fuel pressure. If I understood correctly your data, they are both control fuel pressure readings (?). So what is your system fuel pressure reading (valve closed)? Keep us posted. Tony |
Tony,
Both pressure readings of 72 psi were taken with the valve open (cold control pressure). There was a continuous flow of fuel out of the TPR return but not out of the WUR return. I have not taken another system pressure reading, but as none of the other pressures have changed with any of the changes that I've made, I would expect them to be the same as before. I don't understand how if the WUR and the TPR are not included in the system pressure reading having them open to atmosphere would make any difference in a system pressure reading either. I'm fairly confident that the WUR is the root of the control pressure issue at this point based on all the testing over the past 20 days and the results from today. Should I pull it apart myself and attempt to clean/unclog or can you please recommend someone that would be best to have it rebuilt? Once I've got a clean, well adjusted WUR with good return flow, if there are additional issues that need to be addressed, I will address them at that point. Thanks, Steve |
Please update the status..........
Steve,
The last email I got from you stated that the refurbished WUR -009 did make the engine run for the first time after several futile attempts in so many years. It would help others if you update this post. Sharing your experience with us would benefit others that might encounter or have similar problem with their cars. Thanks. Tony |
Please update and share your results.........
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Steve, I know the engine started right always for the first time with the rebuilt WUR. So how's the car doing these days? Still running OK? Or PM me. Thanks. Tony |
Jim. You say in item no.60 that wur o438 140 129 is for '75 US models and vacuum operated. I have one with that no. with no vacuum fitting [not original to my car] Think I will have to start a story of my own. I'm having starting/running problems after a long sleep [the car!] + it appears to have an identity problem too.Regards,Michael.
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