6.1 bar system pressure

We had a cold start problem with the cabby sportline, the wire to the cold start valve had snapped, I repaired this and took the valve out, checked the spray duration and pattern - both spot on. Cold start problem gone away.

So now the car starts fine but now has the tendancy to stall for the first 2 to 3 mins during warm up, it will idle fine, rev up and drive fine but coming off the revs when changing gear it will just stall.

So the only thing that has changed is the reconnection of the cold start valve !! I have double checked that it only sprays for a few seconds and does not leak.

Measured the control pressures, 2 bar cold and 3.9 bar warm.
However system pressure is 6.1 bar, this 0.7 bar too high, is this dangerously too high ? What effect would it have ?

Bentley says that this is caused by either a faulty metering unit or a partialy blocked return fuel line. Going to try taking the return line off later to see if that drops the pressure.
What I am not sure about is if someone has shimmed the pressure regulator in the metering head in the past, is 0.7 bar realistic to get it reduced by ?

First thing, is obviously to check for kinks and blockages in the return line. This might not be as simple to fix, if the blockage lies within the metering head.

If that's ok, then you should be able to adjust to within specs, having said that I can't remember if you add or remove shims, to increase/decrease pressure, so you might run out of shims to remove. In which case you'll need a new metering head. You can only try/have a look though?

if its the same as the RS turbo metering head then you add shims to increase the pressure

Someone once advised me to run at about 6.0 bar, said the spray pattern from the injectors is more even. I tried it and it didn't make any difference. If your return lines are not blocked and there's no other problem just remove one of the thin shims, that should put you back to around 5.4 Bar.

The only real issue with the 'overpressure' is:

1. You'll be putting more strain on the pump, so it won't last as long
2. There is a greater chance of a fuel connection which would be otherwise leak-free, of leaking fuel.

Thanks for the advice guys.
Going to measure the pressure with the return line removed from the metering head tomorrow, if no change I will remove a shim.

The car runs really well except for a tendancy to stall during the first minute of running, the weird thing is that it will idle but if you blip the revs it will either stall or drop really low and then recover instantly to idle. If it does stall it struggles to restart ( but always does) like it is either flooded or starved of fuel.

The above all started with cold start problems, I found a broken wire to the cold start valve, fixed it, cold start sorted but now the weird stalling problem !! I have had the cold start valve out and it sprays and operates fine. I am now starting to think that I have a weird electrical problem that causes the thermo time switch to give the valve another spray when coming off the revs to change gear !!

Thoughts ?