The regulator has a fuel in flow from the metering head and restrictions in this effect the pressure on the plunger in the metering head which makes it move more or less to give weaker or richer fuelling as required.
The inlet to the regulator is via a 13mm banjo connector under which there is a mesh guaze which can clog up. I disconnected the fuel and vacuum pipes and the power supply and removed the unit from the base plate. It is held on by two 5mm allen bolts. I investigated the gauze and whilst is a bit tricky to pull out I felt I had nothing to lose. Underneath were a further four gauzes, none of which were very clean. These were easy to remove so I gave all a brush with some degreaser and set them aside.
The mechanism within the regulator works via a bi metal strip. As this heats up and bends upwards it allows a spring to expand and operate a small plunger that cuts off the fuel flow. The vacuum, via a sealed diaphragm counters this under load and allows greater fuel flow. To check everything was working I took the unit apart. It is held together by four screws accessed from below and you will probably need to hold the unit in a vice to undo them.
Once apart this is inside the top section.
I removed the spring and heating element by removing a U clip from under the electrical connector on the top of the unit and then undoing the 10mm nut. The element should have resistance of .25 ohms if all is well so I checked and mine seemed close enough.
You then have access to four screws that hold the plate that the plunger is within.
Again, these are very tight but once removed you will find a metal plate that acts against a rubber seal which controls the fuel flow.
Clean off any fuel residue, make sure the small plunger is free and then reassemble.
The little plunger is operated by a metal pin actuated by two springs on the base section.
These just rest in place and are not secured at all. I just made sure everything was clean then reassembled the whole unit. I found it easiest to place the pin within the locating hole on the plunger, holding the unit upside down, place the springs around it and rest them on the bi-metal and then lower the bottom half carefully over this and locate them into the fitting in the base. Then its tighten the nuts and refit to the car. In my case this has made a world of difference.
