PeachParts Mercedes-Benz Forum - View Single Post

stevebfl · #5 05-15-2005, 10:53 AM

Fuel pressure regulators are of course attached to the return, but they start in the pressure side. This is basic *****. They control pressure by dumping to the return. Just what purpose can a regulator accomplish with both sides hooked to the fuel return.

If we are to have a technical discussion you will have to state a technical theory of operation that fits your stated concept. I have stated that the fuel from the frequency valve is dumped through the diaphram into the return line. There is no significant pressure there. The frequency valve IS a pressure regulator. It regulates the lower chamber pressure by dumping it. By lowering the pressure the mixture is richened.

There are two other pressure regulators in that K-jet w/Lambda system. The first IS the true system pressure regulator. It is internal to the fuel distributor and regulates by dumping the excess into the return. The system pressure flows through a restricting oriface to the top of the metering piston and is re-regulated to a lower control/warm-up pressure. This pressure opposes the piston and leans out the mixture by resisting movement of the piston. It also regulates pressure by dumping the excess to the return. All of this dumping could buzz the steel lines since it would be pulses of fuel at velocity. Thus they have installed dampeners to keep the vibrations down.

The above is a simple theoretical description of the pieces you wish to call pressure regulators and the real regulators that DO exist in the system. I've worked on this system designed that way and taught that way by MB and Bosch since it came out in Volvos in 1979 and MB in 1980.

I await such a theoretical description as you see it using pressure regulators in the return side of the system. The only way they could regulate any pressure would be to defeat the operation of the real regulators that are before them in the system. Since the frequency valve regulates pressure just what do you suppose takes place between it and what you wish to call a regulator.

What do you say about the obvious part number relationship to the diahram dampener (not the regulator) I stated above in the D-jet system? Or do you claim that both parts 176 and 206 are pressure regulators. Your part book translation don't work there. You have been mislead by a poor translation in a parts book. The answer is in the actual design. Propose to us the system as you see it using two more pressure regulators, besides the system, control, and lower chamber pressures.