Is there a fuel cut off switch for the 850 T5?

**850t5** · Thursday 17th March 2011, 14:39

I've been testing my MBC out and last night I took the car out and held it in 4th gear to see the boost level

Then it just cut out? The engine sounds fine (on turn over) and the electrical system seems fine too.

I'm not sure if these cars have a fuel cut off switch due to over boosting. Is there a fuel cut off switch and where is it?

Thanks in advance

Danny.

**Al115** · Thursday 17th March 2011, 14:55

Doubt it. Fuel cut is kind of the opposite of what you want under overboost.

**Tomcat** · Thursday 17th March 2011, 15:55

See if there's pressure in the fuel system by pressing the small valve on the r/h side of the fuel rail.

**Al115** · Thursday 17th March 2011, 16:28

Turn ignition to pos II, hear fuel pump whirr up, when it stops, turn ignition off, and press schrader-type valve on the end of the fuel rail as Tomcat says. Have a rag in place to catch the petrol that will spill out. Best to do this with a cold engine!

No fuel or just a dribble means... no fuel to the rail.

**850t5** · Thursday 17th March 2011, 16:31

Ok thanks

The engine just cut out when I was under full throttle in 4th. My first thought was fuel pump. I shall dig deeper

**850t5** · Saturday 19th March 2011, 15:03

I've put the ignition on and then tried the button on the fuel rail. How much pressure should the fuel come out with? All I get is a couple of blobs shoot out but I wouldn't say they were coming out with much force at all?

Thanks for the advice so far lads

**Alan M** · Saturday 19th March 2011, 15:33

Check the fuel pump relay on the front panel above the fan. Wiring can be broken quite easily there on the plug due to the way it is bent round to accommodate the relay postion.

**Niles** · Monday 21st March 2011, 10:34

if the MBC is plumbed in properly and you floor it in 4th to check the boost levels if the turbo pushes over 14psi it will kick in 'overboost protection' (ignition cut). The car will not go over 14psi without a remap. Fact. It is not curable any other way. Set the MBC lower than 14psi or get it remapped.