Stag 300-8 System on BMW 540

[ZiggyB]

Hi All,
I wonder if anyone can help with my LPG problem.
My 540 has a Stag 300-8 system fitted with Valtek Red 3 Ohm Injectors and a Landi Renzo Vapouriser.
Until recently (40K odd miles and 3 years of use) all was fine.Then the car started to run very lumpy apart from on warm up. Initially I diagnosed a spilt in a vaporiser diaphram which was rectified which helped but it's still the same.
I have fitted a new filter, taken off the injectors and cleaned them and tested for operation by putting 12V across each of them (I can also hear each injector opening when the car is running).
To make it even run at the minute the multipliers are at max (X 2.4) when before they we're about X 1.2 but as soon as the vapouriser becomes warm it runs like @!##.
I did disconnect the heating circuit to the vapouriser and it ran fantastically due the the extra density of the cooler gas but, obviously, had running problems as soon as the vapouriser froze up!
This leads me to think that the injectors aren't opening fully although they are all working. I disconnected one of the lpg lines fron injector to manifold while the car was running and the amount of gas coming out is like a mouse's fart (i.e. not very much).
The pressure in the system is about 1.1 bar which remains constant under all loads (increasing the pressure has minimal effect).
Do Valteks 'wear out'? The rubber dampers on the ends of the pistons look in good order and they all seem to open fully when I bench tested each of them.
Am I missing something stupid like a poor 12V feed to the injectors or a poor earth in the LPG system?
Ideas anyone.
Cheers
Julian

[rossko]

Replace those o-ring bumpstops on the plunger backend. While most go to mush causing richness due to opening further and/or sticking, they can also swell and restrict opening.

[ZiggyB]

Rosko,
Thanks. I'll have a look at them and let you know the outcome.
Cheers
Julian

[lazydocker]

Must admit, the Red Valteks haven't been impressive on the Omega. I've converted several and fond them OK, but the Motogas injectors we're using now are better.

I wouldn't have thought that 40k was enough to destroy them though... My last Omega was 55k down the line on LPG (with Red Valteks) and still running like a dream when I sold it. But I bow to Rossko's superior knowledge

[rysiontko]

Buy injectors, not solenoids.

[rossko]

Just buy some rubber rings for another 40K ...

[ZiggyB]

Hi All,
I've currently removed the 'o' ring buffers from the top of the solenoid plungers until I can get some new ones and can report that the car now runs like a dream (after a re-map of course).
Thanks fro the help.
Julian

[rossko]

My lord be careful ... that must be making an awful clattering and noise means wear ... you could end up buying complete new rails yet.

[ZiggyB]

Hi,
Just running on petrol at the minute but had to make sure for piece of mind I'd fixed the problem.
Thanks again
Julian