Sub tank

[Idle Yorkshireman]

Hi guys I have a 2003 ex-military armoured 105 4.5 petrol with a sub tank and 24,000 miles on the clock. I'm not very mechanically minded so please be gentle......it does not seem to start up from the Sub tank but switches over from main to sub and works ok? I'm sure when I first purchased it would start up straight from the sub tank. It's no big issue as there is always plenty of fuel in both and i just start it on the main, just couldn't work out whether I was going senile or not.
Ps I'm loving my 3 months of ownership so far having moved across from the dark side of the green oval badge with a 110 double cab and Supercharged Range Rover. I've just about adjusted to the lhd, lack of speed at 5 tonne with armour and I don't look at mpg obviously - it's a great machine.

 

[GeekOKent]

Can't help with the why, but my 105 starts ok and runs fine with either tank.

 

[Idle Yorkshireman]

Excellent @GeekOKent - much appreciated. I'll get my mechanic to investigate why when its next in.