What a fantastic guide! Thank you SteveW for taking the time to do this step by step.
I had a similar issue, under a quarter tank the needle and electronic read out were jumping all over the place. One minute 80miles, ----- the next!
Followed this guide to a T and fixed my issue! 90 odd miles back in my tank and going down slowly!
Only problem is, once i had put the sub and cover back, car wouldnt start and petrol gauge didnt seem to be fixed. Slightly miffed to say the least. Took the sub back out and the tank cover off....i hadnt connected the pump back up to the loom!
Again, Thank you!