2 questions.
What's it mean Modular V-10?

My V-10 when I started having fuel usage problems.
I found a hole rubbed in one of the vapor lines.
When I repaired it the economy went back up.
Why would this happen.
What effect would this have on the system?
99/250 Super Duty V-10
Thanks,Jerry

 

I cannot help you on the fuel question, but the Modular refers to the tooling at the engine plant. It was set up so they could switch from producing the V10 to the 5.4 V8 to the 4.6V8 in just a couple of days.

 

Google "ford modular".

As for the hose, it depends on which specific hose it might have been.

 

There are 2 vents on the tank.
The rear hose had rubbed a spot and it was sucking air?.
Both hoses run together and go to the canister and to the purge valve.
Thanks,