warm up regulator

I've had problems with my fuel system lately and I think it stems from the warm up regulator.
The car is loosing all fuel pressure when warm and struggles to start, if it starts at all. I have no problem starting the car when cold as I believe the cold start 5th injector negates the need for fuel pressure in the system.

I have replaced the warm up regulator with what I think is from an escort xr3i, both parts have the same bosch part number 0438 140 073. Is this the correct part number?

The old part caused a miss fire and loss of power due to excess fuel pressure.

The new part has no vw part number but the old part was 049 133 403. Is this the correct part number? I have been given a part number 063 133 403 by a friend but if this is the correct number it means my car had the wrong part fitted originally.

Can anybody shed any light on this for me please?

Firstly, how did you measure the pressure? The 5th injector doesn't negate the need for fuel pressure in the system, in fact it needs fuel pressure otherwise it wouldn't squirt fuel. All it does it provides a bit extra fuel for cranking and the first 10-15 secs of running.

It was tested with a fuel pressure gauge at a garage. It was fitted in the fuel line after the fuel filter.

Am I barking up the wrong tree?

No, you're not barking up the wrong tree, but they've measured the fuel pressure in the wrong place. You need to measure it in the line between the metering head and WUR (the thicker of the two), and preforably with a T piece in it. This way, you can measure both the control pressure (which varies with how warm the engine is) and system pressure (constant with temperature). Also, each time you replace the WUR, you need to reset the CO (you'd need a gas analyser for this).

Ask the garage if they have the necessary adaptor fittings to connect it to a K-Jet VW, if they don't, then you'll need to find a better garage or buy the kit yourself.

should you have fuel pressure at the fuel unions at the top of the metering head when pump isn't running ??

just to add to pauls post, you need a tap on the car side of the pipe to the WUR as you need to close it off to measure system pressure (I'm sure thats what he meant about the T piece? )

you will only see full fuel pressure with the fuel pump running, once the pump is switched off the pressure will drop back to the residual pressure setting, and should be at least 2.6 bar after 10 minutes once switched off on a fully hot engine

this guide covers it in detail plus the 'wur tweak' if you have a 16v
http://www.clubgti.com/showthread.php?81658