TheSamba.com :: View topic

Thu Mar 20, 2003 8:36 pm

I have replaced the original 10 gallon tank with a later model 15 gallon tank on my 64 split. I followed the directions provided on vintagebus.com (nice!). The problem is, my bus dies after about 30 minutes of continuous freeway driving. When I open the deck, I see both filters (one from tank to pump, one from pump to carb) are dry. This has happened twice to me. After being stranded on the side of the road for about 20 minutes, I noticed the filters were full of fuel. I originally thought this may be the fuel pump. But after overhauling the pump, the problem still occurs.

So not I believe the problem is venting. I have capped off both tubes at the top of the tank with screwed off hose per the directions on vintagebus. Are there vent plugs that let air in and keep gas from flowing out that I can buy? Is there a special gas cap that I need to buy that facilitates venting? How do you vent your gas tanks? Do you? Does it sound like my problem is something other than venting.

Fri Mar 21, 2003 4:45 am

IM not familiar with bus fuel tanks, but I know about aircraft ones! SImply put, you need a vent of some sort and by the sound of things you have sealed of the factory vent lines?

Fuel evaporation is a much nicer "problem" than a tank trying to do an impression of a balloon in summer. I am guessing there are 2 vent tubes at the top of the tank? as you indicate in your post. If so a pair of weakly sprung one way valves (facing opposite ways) will keep the tank at ambient or close to ambient pressure at all time, and help prevent fuel loss due to evaporation.

Fri Mar 21, 2003 8:18 am

Split bus gas tanks didn't come with vents because it was the job of the cap to allow air to go in and out. You need to get a vented gas cap and you should be fine.

Fri Mar 21, 2003 5:27 pm

Any suggestions on vented gas caps, or just head down to NAPA?

Fri Mar 21, 2003 7:32 pm

On my 66 and 67 buses, I had to 'make' a vented cap. I used the tiniest drill bit in my 'up to 1/2" ' set. 1/64th?
With the cap on, I marked the top. Then drilled a hole thru the top layer of the cap between the inner edge area of the gasket and the center. Then when I put the cap on after putting gas in, I make sure the hole is up.

Sat Mar 22, 2003 11:34 am

You learn something new every day eh? :)

Mon Mar 24, 2003 8:34 am

I did the same thing but went one step further. I drilled the hole just big enough to allow a tack nail (that I shortened) to snuggly fit into it. What this does it allow some pressure build up, but will release when it gets too high. And it doesn't leak gas.

Mon Mar 24, 2003 1:58 pm

I gotta ask? Do you keep a handful of nails in your bus during the summer? I like where this is going, because my next concern was about gas leakage when it came to drilling holes in gas caps. I would assume that it would be minimal unless I parked on a hill right after filling up.

Mon Mar 24, 2003 4:04 pm

Like I said, the nail is pretty snug in the cap. When pressure builds up, you can hear is whistling out the cap. And where it is placed, you would have to be on one hell of a hill to get it to leak (and have a full tank). I put the nail in because it did leak at one time. The whole used to be really small like aufeverprodigy.net did to his. A good vented cap should work fine though.

Mon Mar 24, 2003 7:51 pm

I have not been able to find a vented cap available on the market. The only ones I could find were 'pressure-vented' but they are not truely vented caps. They have to be used on a charcoal cannister/evaporative system.
The repo 211 201 551 cap being marketed as the 56-67 cap is not a vented cap. [at least the ones I have tried] That is why I had to drill a tiny hole in two of mine....

Mon Mar 24, 2003 9:30 pm

There are OG used vented caps available out there. That's what swap meets are for.