Quote:
Originally Posted by Brian Fuller
Ossiblue, thank you for your comments. This helps me to clarify~
I did purchase all new lines, tunnel pressure line and and tunnel return line, new filter in tank, and all new lines that make up connections to the filter/accumulator/ and WUR, etc. Everything new.
"I believe, on your car, the return line from the WUR runs up to the rear of the FD where it connects with the fuel pressure relief valve. From there, both the FD excess fuel and WUR excess fuel share the same line back to the tank."
Yes, that's correct see illustration below:
"Your test description sounds like you disconnected this common return line without isolating the return line from the WUR."
Yes, in my first test I did this. I was trying to see if there might be a clog in the return line at the tank. But then reconnected everything and moved on to a second test which I called the "WUR Bypass test"
I had concluded that the constriction might be in my WUR. What I was trying to do is bypass the WUR to see if fuel would flow freely through all the lines. I connected "B" see illustration below to "B" above and "A" to FD with the fuel test gauge in between and valve open.
 (copied this image from other post)
What I am discovering is when I am doing the standard Fuel pressure test my pressure is way, way too high. What I have tried to do is isolate where the constriction is and it would seem that fuel is not getting through the WUR... my pressure goes high and stays high 4.8bar.
When I bypassed the WUR, the fuel flows freely and there does not seem to be any constriction in any of the lines.
BTW, I did disconnect both fuel lines from the WUR and blow compressed air (60psi) on the WUR fuel intake side, very little air would pass through. But I don't know if this is proof that the WUR is clogged. Which begs the question, do WURs get clogged? As I mentioned the screen looked clean so it would have to be an internal clog.
All the Best,
Brian
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Thanks for the clarification Brian. You'll see I edited my post as you were typing and now I see that all lines appear to be clear. The problem seems to be with the WUR, as you've found.
You can disassemble the WUR easily. Once the bimetallic arm is removed, you can open the bottom of the diaphragm housing and remove the two metal diaphragms. You'll now be able to see the inside of the entry and exit ports. The port bores are very small, but you should be able to see light through them and blow air, with your mouth, through them (though it will be difficult.) It should be clean on the inside of the housing, and the diaphragms should be clean as well. There is an O-ring that seals the bottom of the housing that should be checked before reassembly. This is the only area that could account for the blockage. Since your control pressure never changes from your system pressure, the only possibility, other than a blockage, is the pin that pushes up on the diaphragms is not adjusted correctly, but that is a bit remote if no one has been messing with the WUR.
Regarding the post about the functioning of the heating element, at this point the issue is moot. The heating element only causes the pressure to
rise from cold control pressure and yours does not drop below system pressure. Still, it's good to check the functioning of the heating element. You can do that easily, especially if you disassemble the WUR for the blockage. Apply 12v to one pin of the element plug and ground the other. Can you feel heat emanating from the heating element? Even if you don't disassemble the WUR, after about 4 minutes you should be able to feel the heat through the body of the WUR if the element is doing it's job.