924Board.org

[Lizard]

how do they work, can someone send a link to a page of a cross section,
also is it possible to damage them if run backwards?
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3 928s,

[CMXXXI]

They work by "bleeding off" the pressure in the fuel circuit that acts on the top of the plunger located in the fuel distributor. With more pressure on top of the plunger, it takes a greater flow volume to displace the plunger than it does with lower pressure. It results in a richer mixture with a lower pressure, and a leaner mixture with a higher relative pressure.

Try this link for some diagrams of the cross section. It's from SpecialTAuto, a DeLorean specialist, but the devices function the same in all CIS applications.
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'79 Eurospec 931

[Roger]

Not sure if you are asking about the WUR or an FPR. I am not sure wich Bosch system this artical refers to but I found it on a google search. Sorry I could not find any diagrams.

The regulator's job is to keep the pressure in the fuel system to a constant 28 psi. It does this with a spring-loaded diaphragm that controls a valve. The valve, when opened by excessive pressure in the fuel lines, uncovers a fuel line that returns excess fuel to the fuel tank.

The vacuum connection is there to help reduce emissions during deceleration. During deceleration, the vacuum connection serves to open the fuel return valve wider, which reduces pressure in the system and prevents excess hydrocarbon emissions due to less fuel being injected as a result of the lower pressure in the system.

This is a very nicely designed device in that it provides for an automatic self-adjusting pressure regulator and emissions control device all rolled into one. The simplicity of the design also contributes to its reliability; the fuel pressure regulator rarely, if ever, goes bad. There's just not much to go wrong with it.

Unfortunately, it's not particularly tuneable either. With Bosch's older FI system, D-Jetronic, the fuel pressure regulator was adjustable. The L-Jetronic pressure regulator is not.
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1981 924 NA

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.