WUR Repair Today
04-23-2012, 01:51 PM
#1
Racer
Thread Starter
WUR Repair Today
"Repair" being a loose term, I am delving into the WUR today as it exhibits some weirdness:
System pressure good
Dead cold pressure good
Warm pressure less than 3 bar
If I tap the side of the WUR the warm pressure goes up to 3.8 or down to 2.4. I mean "tap" lightly. This silliness demands investigation. I am hopefully going to find a bunch of crud inside of it and can clean it out and use it.
Pictures to follow.
System pressure good
Dead cold pressure good
Warm pressure less than 3 bar
If I tap the side of the WUR the warm pressure goes up to 3.8 or down to 2.4. I mean "tap" lightly. This silliness demands investigation. I am hopefully going to find a bunch of crud inside of it and can clean it out and use it.
Pictures to follow.
04-23-2012, 03:23 PM
#3
Three Wheelin'
this was posted some time ago, sorry can,t remember who ? might help ?
http://www.ferrari400parts.com/Warmu...atorrepair.php
Ken
80 928 S
5 Speed
UK
http://www.ferrari400parts.com/Warmu...atorrepair.php
Ken
80 928 S
5 Speed
UK
04-23-2012, 06:15 PM
#4
Racer
Thread Starter
I used one from landsharkoz and another from the VW forum, which uses his as a basis. I'm currently at "we'll see" - I removed the WUR, opened it up, cleaned it out, knocked both the plug and the regulator body back out, and reinstalled. Initially got 10psi, which was good considering I needed to knock it up (he he). I was able to get the cold to 2 bar (30 psi), within spec for the 72 degrees we're having today. On the warm side I have to wait until tomorrow because the plug to the WUR cracked and, although I have a new one, I decided to rebuild the entire FI harness as it is all pretty nasty. Too simple of a harness to leave like it is, especially since it carries 12V all around the fuel system.
The guts of the WUR were fine, not leaking, but the O-ring was a little flat and replaced. I get how the pressure stuff works now. Damn simple device but calibrating with a hammer and punch seems wrong.
The guts of the WUR were fine, not leaking, but the O-ring was a little flat and replaced. I get how the pressure stuff works now. Damn simple device but calibrating with a hammer and punch seems wrong.
04-23-2012, 09:41 PM
#6
Rennlist Member
I have tried rebuilding a wur, and found the size of the regulator O-ring to be sensitive. IIRC my next try is either 14.5 or 15mm rings. A low hot control is pretty unusual, unless the regulator body or the bold have been moved. Converting the bolt to be able to pull it out with a bolt and washer is easy to do. Keep your exeperiences coming please. I almost have a test rig set up, with a spare pump, gauge, adjustable regulator (to set system pressure), and using kero instead of gasoline - difficult to get the time lately to work on it.
jp 83 Euro S AT 54k
jp 83 Euro S AT 54k
04-24-2012, 08:50 AM
#7
Racer
Thread Starter
I have tried rebuilding a wur, and found the size of the regulator O-ring to be sensitive. IIRC my next try is either 14.5 or 15mm rings. A low hot control is pretty unusual, unless the regulator body or the bold have been moved. Converting the bolt to be able to pull it out with a bolt and washer is easy to do. Keep your exeperiences coming please. I almost have a test rig set up, with a spare pump, gauge, adjustable regulator (to set system pressure), and using kero instead of gasoline - difficult to get the time lately to work on it.
jp 83 Euro S AT 54k
jp 83 Euro S AT 54k
I wasn't clear - I had low pressures once I rebuilt it because I knocked both the regulator and the plug out a few MMs. I wanted to start with low pressure and work my way up, a safety measure.
I found the o-ring to be the whole kit and caboodle, everything in the WUR works to apply pressure to it. The amount of o-ring compression by the four screws determines what I would call the unloaded pressure. A load is then applied to the bottom of the regulator plate by the pin and springs; this load creates the control pressure. It is further loaded by the heated rod and then dynamically altered by vacuum.
I may have to take it apart again today but I have it down to a science now. I think I need to set my regulator (which is now set to 2 bar) to just over 2 bar, then set the plug to bring it up to 2 when cold. Just a theory, I'll explain better if it works.
Last edited by bradartigue; 04-24-2012 at 09:04 AM. Reason: poor word choice
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04-24-2012, 12:27 PM
#8
Instructor
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WUR "debugging" procedure
When I serviced my WUR I checked it out in stages.
1. With only the o-ring and thin metallic diaphragm installed in the upper regulator body (no heated rod, springs, or pin). This gives the lowest possible WUR pressure, about 1 bar. You can actually do this with the WUR disassembled as only the top half is needed for this connection. This way you can check for internal leaks, too. If the pressure is too high, the input filter is probably clogged. I sprayed carb cleaner backwards through the input port from the inside after disassembling the regulator body to clean mine. If this doesn't fix it, you can wrap a rag around the output side and loosen the fitting. Normally, the pressure should stay the same when you do this. If the pressure drops off, though, there is a blockage in the return line somewhere. If you still have high pressure, you can disconnect the output line completely; if nothing is coming out at all, and you are certain that you have your CIS test gauge hooked up the right way, then the WUR is plugged up somehow. If the pressure is too low, the O-ring may be too thick or you haven't tightened the four small screws on the inner regulator enough. Make sure to do test #2 also, if #1 is a little high or low. If #2 is ok, don't worry about it. If #1 is way off, though, you have a problem.
2. Adding the springs and inner pin (no heated rod). This gives the maximum warm pressure. check it with and without vacuum at the side port. Should go up from 3 bar to about 3.6 bar when you apply vaccuum as the lower diaphragm pushing on the inner spring actually goes UP when vacuum is applied (not what you'd expect). It can be tricky to get the inner spring to seat properly. If the pressure drifts back down or doesn't rise when you apply vacuum at the side port, the diaphragm at the bottom of the WUR is bad or the inner spring is not well seated. Also, if you've replaced the gasket between the two main pieces of the WUR, the control pressure can be reduced if you don't tighten the two pieces down all the way. This gasket, by the way, is not critical as it is not exposed to vacuum; the top hose attachment is to atmospheric pressure only. This pressure can be adjusted by knocking the regulator body in (if you want a higher value) or out (if you want a lower value). Or, you can make another pin from an appropriately thick nail, round out the ends, and keep filing off a tiny bit to drop the pressure a little each time until you get what you want.
3. Finally, add back the heated rod, but don't connect the power to it. cold engine. jumper the fuel pump relay. Now measure the cold pressure. If #1 and #2 were in spec, you can tweak this by knocking the pin that the heated rod attaches to down/in (for lower cold pressure) or up/out (for higher cold pressure).
4. Connect power to the WUR, with pump relay still jumpered. Control pressure should slowly rise to full warm pressure measured in # 2 over about 5-7 minutes. If the pressure goes DOWN, the rod is in upside down. Then, apply vacuum to the side port. It should rise another 0.6 bar or so. If the pressure doesn't get close, then the rod heater element or wiring may be bad. Check for 12 volts at the connector with the pump relay jumpered. If voltage is good, check the resistance across the terminals on the WUR with the plug disconnected. Should be somewhere between 20-80 ohm depending on the version of the WUR, IIRC. If still low, start the engine and see if engine heat brings it to the correct pressure over 20 minutes. If so, this suggests that the heating element isn't working properly.
5. Leave engine running until operating temperature reached, and confirm control pressure = expected warm temp.
1. With only the o-ring and thin metallic diaphragm installed in the upper regulator body (no heated rod, springs, or pin). This gives the lowest possible WUR pressure, about 1 bar. You can actually do this with the WUR disassembled as only the top half is needed for this connection. This way you can check for internal leaks, too. If the pressure is too high, the input filter is probably clogged. I sprayed carb cleaner backwards through the input port from the inside after disassembling the regulator body to clean mine. If this doesn't fix it, you can wrap a rag around the output side and loosen the fitting. Normally, the pressure should stay the same when you do this. If the pressure drops off, though, there is a blockage in the return line somewhere. If you still have high pressure, you can disconnect the output line completely; if nothing is coming out at all, and you are certain that you have your CIS test gauge hooked up the right way, then the WUR is plugged up somehow. If the pressure is too low, the O-ring may be too thick or you haven't tightened the four small screws on the inner regulator enough. Make sure to do test #2 also, if #1 is a little high or low. If #2 is ok, don't worry about it. If #1 is way off, though, you have a problem.
2. Adding the springs and inner pin (no heated rod). This gives the maximum warm pressure. check it with and without vacuum at the side port. Should go up from 3 bar to about 3.6 bar when you apply vaccuum as the lower diaphragm pushing on the inner spring actually goes UP when vacuum is applied (not what you'd expect). It can be tricky to get the inner spring to seat properly. If the pressure drifts back down or doesn't rise when you apply vacuum at the side port, the diaphragm at the bottom of the WUR is bad or the inner spring is not well seated. Also, if you've replaced the gasket between the two main pieces of the WUR, the control pressure can be reduced if you don't tighten the two pieces down all the way. This gasket, by the way, is not critical as it is not exposed to vacuum; the top hose attachment is to atmospheric pressure only. This pressure can be adjusted by knocking the regulator body in (if you want a higher value) or out (if you want a lower value). Or, you can make another pin from an appropriately thick nail, round out the ends, and keep filing off a tiny bit to drop the pressure a little each time until you get what you want.
3. Finally, add back the heated rod, but don't connect the power to it. cold engine. jumper the fuel pump relay. Now measure the cold pressure. If #1 and #2 were in spec, you can tweak this by knocking the pin that the heated rod attaches to down/in (for lower cold pressure) or up/out (for higher cold pressure).
4. Connect power to the WUR, with pump relay still jumpered. Control pressure should slowly rise to full warm pressure measured in # 2 over about 5-7 minutes. If the pressure goes DOWN, the rod is in upside down. Then, apply vacuum to the side port. It should rise another 0.6 bar or so. If the pressure doesn't get close, then the rod heater element or wiring may be bad. Check for 12 volts at the connector with the pump relay jumpered. If voltage is good, check the resistance across the terminals on the WUR with the plug disconnected. Should be somewhere between 20-80 ohm depending on the version of the WUR, IIRC. If still low, start the engine and see if engine heat brings it to the correct pressure over 20 minutes. If so, this suggests that the heating element isn't working properly.
5. Leave engine running until operating temperature reached, and confirm control pressure = expected warm temp.
04-24-2012, 04:35 PM
#9
Racer
Thread Starter
What I've arrived at is the o-ring has simply outlived itself. Regardless of procedure I cannot achieve good warm pressure without sacrificing cold pressure, and connect get good cold pressure without excessive warm pressure. This is consistent with my belief that the o-ring has simply become too elastic and provides adequate control over containment of fuel but not adequate resistance to maintain pressure.
With cold pressure @ 2 bar my max warm pressure is over 4 bar; with warm pressure then adjusted to 3 bar my cold pressure drops to 1 bar.
This explains the obvious adjustments to the WUR made by someone in the past, and why I believe it to be the culprit for my woes. I'm going to order a new one and see what happens, I would simply replace the O-ring but my heater element is cracked and even though it holds resistance and heats properly I can't drive around with an electrical device inside a fuel device that I know is falling apart.
I learned quite a bit about the WUR, and it really isn't very mysterious at all. Simply put, everything inside the device acts to either apply or reduce pressure on a plate that compresses an O-ring. The resulting fuel pressure dictates the extent of opening on the air metering door, which actuates the fuel delivery valves. The range of adjustment is relative to the o-ring's elasticity, or in my case, .5 bar to 4.8 ~ bar (relaxed to fully compressed), which apparently is too elastic.
With cold pressure @ 2 bar my max warm pressure is over 4 bar; with warm pressure then adjusted to 3 bar my cold pressure drops to 1 bar.
This explains the obvious adjustments to the WUR made by someone in the past, and why I believe it to be the culprit for my woes. I'm going to order a new one and see what happens, I would simply replace the O-ring but my heater element is cracked and even though it holds resistance and heats properly I can't drive around with an electrical device inside a fuel device that I know is falling apart.
I learned quite a bit about the WUR, and it really isn't very mysterious at all. Simply put, everything inside the device acts to either apply or reduce pressure on a plate that compresses an O-ring. The resulting fuel pressure dictates the extent of opening on the air metering door, which actuates the fuel delivery valves. The range of adjustment is relative to the o-ring's elasticity, or in my case, .5 bar to 4.8 ~ bar (relaxed to fully compressed), which apparently is too elastic.
04-24-2012, 06:49 PM
#10
Racer
Thread Starter
I put in a longer post about this but Rennlist is giving me fits today, as in, I post something and it errors out. Therefore, here is a post from my blog on the WUR, with pictures:
http://www.artigue.com/porsche/928-w...-regulator-wur
http://www.artigue.com/porsche/928-w...-regulator-wur
04-24-2012, 07:30 PM
#11
Rennlist Member
Brad,
If your heater is electrically OK, but just has a crack in the stuff covering the element, cover it with something like a NOT hard setting epoxy, or other type of glue.
I suspect you have run up against the issue of having the EXACTLY correct O ring size - not so much the diameter, but the section. Check out the parts available at ferrari400parts.com - he does kits with all required parts. I have found that just testing the car stationery, idling, for getting enough heat into the WUR to see a true hot control pressure, is not good enough. I once saw 40-45psi idling stationery, thinking I was done, but withing 10 mins of driving and getting more heat, the power was largely lost, and control was up near 60psi. The WUR needs to be really soaked throiugh with heat to be reliable when hot. Your WUR looks like it has the ssimple version of the heated element - mine (086) has some sort of secondary bimetallic strip that opens/closes contacts inside - I think this turns off power to the main strip when the secondary strip has been fully heated through by conduction from the block.
jp 83 Euro S AT 54k
If your heater is electrically OK, but just has a crack in the stuff covering the element, cover it with something like a NOT hard setting epoxy, or other type of glue.
I suspect you have run up against the issue of having the EXACTLY correct O ring size - not so much the diameter, but the section. Check out the parts available at ferrari400parts.com - he does kits with all required parts. I have found that just testing the car stationery, idling, for getting enough heat into the WUR to see a true hot control pressure, is not good enough. I once saw 40-45psi idling stationery, thinking I was done, but withing 10 mins of driving and getting more heat, the power was largely lost, and control was up near 60psi. The WUR needs to be really soaked throiugh with heat to be reliable when hot. Your WUR looks like it has the ssimple version of the heated element - mine (086) has some sort of secondary bimetallic strip that opens/closes contacts inside - I think this turns off power to the main strip when the secondary strip has been fully heated through by conduction from the block.
jp 83 Euro S AT 54k
04-24-2012, 09:14 PM
#12
Racer
Thread Starter
Brad,
If your heater is electrically OK, but just has a crack in the stuff covering the element, cover it with something like a NOT hard setting epoxy, or other type of glue.
I suspect you have run up against the issue of having the EXACTLY correct O ring size - not so much the diameter, but the section. Check out the parts available at ferrari400parts.com - he does kits with all required parts. I have found that just testing the car stationery, idling, for getting enough heat into the WUR to see a true hot control pressure, is not good enough. I once saw 40-45psi idling stationery, thinking I was done, but withing 10 mins of driving and getting more heat, the power was largely lost, and control was up near 60psi. The WUR needs to be really soaked throiugh with heat to be reliable when hot. Your WUR looks like it has the ssimple version of the heated element - mine (086) has some sort of secondary bimetallic strip that opens/closes contacts inside - I think this turns off power to the main strip when the secondary strip has been fully heated through by conduction from the block.
jp 83 Euro S AT 54k
If your heater is electrically OK, but just has a crack in the stuff covering the element, cover it with something like a NOT hard setting epoxy, or other type of glue.
I suspect you have run up against the issue of having the EXACTLY correct O ring size - not so much the diameter, but the section. Check out the parts available at ferrari400parts.com - he does kits with all required parts. I have found that just testing the car stationery, idling, for getting enough heat into the WUR to see a true hot control pressure, is not good enough. I once saw 40-45psi idling stationery, thinking I was done, but withing 10 mins of driving and getting more heat, the power was largely lost, and control was up near 60psi. The WUR needs to be really soaked throiugh with heat to be reliable when hot. Your WUR looks like it has the ssimple version of the heated element - mine (086) has some sort of secondary bimetallic strip that opens/closes contacts inside - I think this turns off power to the main strip when the secondary strip has been fully heated through by conduction from the block.
jp 83 Euro S AT 54k
I have so much work to do on this car and I've been farting around with the fuel system for a month. I found an 063 unit like the one I have, which apparently is the rarer of the four used in 1979 (2 for AT, 2 for MT), so I feel like I was called to it. Anything to convince myself!
The WUR is the 2nd the last stop in the fuel system, everything will be new except for the injectors and fuel distributor, and frankly when the car runs it runs so well that I doubt the injectors are at fault. The saga...continues........
