First time MH owner and bought a Hymer B634 (2.8 Fiat base) in the summer and loving it. Had a few trips out and travelled all over Cornwall - she ran like a dream. Have her in outside storage at the moment due to the cold and Covid. Popped down few days ago just too start her up and give the engine a run. Started ok - then after a minute our so stopped running - started up and same issue stooping after a few minutes. Now won't start at all - battery ok and turns over well. Seems like some type of fun issue. Anyone any ideas?