Hi, a quick question. My truck runs the 8BA motor, using an electric fuel pump. The fuel cap fitted leaked a lot when the tank is 3/4 to full. I removed the cap and noticed the rubber seal was missing. I made a seal from some flat rubber. But after a few hours noticed that the fuel pump was much louder than it usually is. It is a new pump by the way. The cap does not appear to be vented, I am assuming that it probably should be a vented cap ?.

Suffolkman

 

Yep, definitely.

 

Yes, and some of the repop caps that i've purchased (yes multiple) did not vent or fit correctly and i found out the hard way last summer driving around. My truck started losing power and stalling til it finally wouldn't start. It was seeming like it was not get fuel after a while messing with it along the road it finally started and i limped back home. I pulled it into the garage and shut it down then started to pull out my manual when i heard the gas tank "oil can". It had so much vacuum pressure that it was starting to try and collapse. i removed the cap and the air hissed going INTO the tank. That's when i decided to find a NOS cap. No problems anymore with that.

 

Check out this thread, there are others too.
https://www.ford-trucks.com/forums/1...49-vented.html

 

Without any fuel tank venting after a while the pump will not be able to compensate for the fuel used and the engine will stall.

 

There's supposed to be a rubber seal!???

Mine vents great either due to missing rubber or bent or design...

 

Yes, it was obvious that there should have been a seal, but I suspect that someone removed it to make the cap vent. I think I have found a new vented cap that will fit. Thanks to all for their interest.

Suffolkman

 

1948/72 use the same vented fuel cap, except 1970/72 F100 with Evaporative Emission.

 

Not exactly, 48-50 have a larger opening for some reason. https://www.ford-trucks.com/forums/1...l#post17191810