I have a 2008 e250 just got from my passed brother law. It has sat for a year after his death ran good had all maintenance done. But now it would not crank. Had towed home charged battery. Still nothing triednothing tried jump start, nothing but click. Replaced starter and replaced battery, cleaned all terminals . now it cranks slow for sort time but not fast enough to start any ideas.

 

Its 4.6 eng.

 

Three things,
Cables corroded internally or connections at other end from battery,
Battery is not fully charged,
Problem with starter, could be solenoid on starter or starter itself.
Might be a good idea to remove a few plugs and see if they are wet. If so, maybe contaminated fuel. All levels check out good?
Coolant and oil?