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The K-Jet Warm Up Regulator (WUR) or Control Pressure Regulator (CPR) is an expensive and precision device and I have had two of them fail. The basic Bosch 004 type unit without the vacuum diaphragm. It seems from the Internet that the most common failure of the WUR is that the filter on the inlet port gets restricted or blocked, excluding some WURs that do not have an inlet filter, so producing a high control pressure resulting in a lean mixture behaviour of the engine.
This is what happened to me since on dismantling the WUR valve body, the diaphragm face was debris and rust free, but then dissecting the body with a hacksaw revealed a restricted inlet filter stack. I got a replacement junkyard WUR for A$5 but want to know what to do to make it reliable - dont want anymore blockage. Reconditioned WUR is A$279!!
On removing the WUR inlet banjo bolt the filter looks fairly coarse and clean but underneath this are four more stainless steel filters of various grades. The filter stack top to bottom is coarse, fine, superfine, fine, coarse. So you cant see that the superfine is choked.
Since some WURs are filterless, some Internet articles suggest punching a hole through the filter stack with a scriber to make the WUR "filter-less" or tearing out the filters with long nose pliers. The metal O-ring retaining the filter stack looks non-removable. This is a fast fix but as even a clean filter stack must present some restriction to fluid flow, (Bosch spec 160 to 240 cc/minute through WUR)so did removing it significantly change the control pressure (outside Bosch specs tolerance values) as evidenced by engine performance (or by JC Whitney K-Jet pressure test gauge?)
Some articles suggest completely dismantling the WUR and blasting carby cleaner through the hole in the periphery of the valve body to reverse flush the filter stack. But the WUR is a precision device so I wonder if on re-assembly its still within factory-set tolerance?
BTW some WUR "re-conditioning trade secrets" can be found at http://www.taunusfinland.com/tiedostot/ford/K-Jetronic/wurfix.pdf which helps better understand the WUR but I am seeking the actual practical experience of BrickBoard members.
sutherml
1979 244GL 535,000 km
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