,
… Sounds like tank sender unit.
That or corrosion on the contacts in the electrical connector to the tank sender unit.
Don’t know what iv done here tried to reply to the comments and cleared my original message 
You have pressed edit instead of post reply and edited your original message lol
Was it meant to be your twice daily post on how bad Downton are and how happy you are now you left? 
Darkside:
Was it meant to be your twice daily post on how bad Downton are and how happy you are now you left?
Was about a problem with truck,but was trying to reply on my phone not my tablet.
Not very good with phones me brain too slow and fingers too fat