Wow Ralph...What a memory!

Is this the thread you were referring to?

http://barthmobile.com/eve/forums/a/tpc/f/3631087061/m/...411097061#8411097061

Yes Lee that was the post, seem to be having the same problem that you are having. I have a 1976 but it has the valve that Bill posted earlier, on my 76 the engine fuel pump has a return line going back to the right tank so when I'm using the left tank I still have fuel
going back into the right tank.

Ralph
1976 27' Barth
454

quote:

Originally posted by REGLOVER:
Yes Lee that was the post, seem to be having the same problem that you are having. I have a 1976 but it has the valve that Bill posted earlier, on my 76 the engine fuel pump has a return line going back to the right tank so when I'm using the left tank I still have fuel
going back into the right tank.

Ralph
1976 27' Barth
454

Hmmmm.........I wonder if there is an orifice that is too large on Lee's fuel pump. The return line needs only the tiniest orifice for vapor lock mitigation. But even a small amount of fuel being pumped back into a full tank would be inconvenient. I guess the drill would be to determine which tank had the return line and burn it down some before switching. Perhaps blocking the return line with a ball bearing would work for temporary trouble-shooting.

This seems to be a bit of poor engineering, anyway. May lightning strike me if I disparage Barth engineering unjustly. The three port Pollak valve pictured does not address return lines. Pollak does make a six port valve with return line switching ability. Or one could simply put another three port valve in the return system so that the tank that was being drawn down would receive the returned fuel.

I am a little rusty on all of this, as I have not used an engine-driven fuel pump for decades.

...Yours was designed that way?

What happens if you hit the road burning off the left tank and the right tank is topped off?
Can you actually pump fuel overboard?

Then again, maybe that's just the nature of the beast, including mine, and it took me 3 years to figure to out.....I guess it's easy enough to compensate for IF you're aware of the system's plumbing...

Thanks for the info......!

Lee theres no doubt that my right tank would overflow if it were topped off and I ran on the left tank for a period of time. I usually run for two hrs on right then switch to left until close to empty then back to right.
When I first purchaced the Barth back ln 01 I was told that I should not have any liquid returning back to the tank so I installed a new engine driven fuel pump which produce the same results, now I switch tanks like the pilots do.

Ralph

quote:

Originally posted by bill h:
I guess the drill would be to determine which tank had the return line and burn it down some before switching. This seems to be a bit of poor engineering, anyway.

quote:

Originally posted by REGLOVER:
I usually run for two hrs on right then switch to left until close to empty then back to right.
Ralph

Ralph, it sounds like you've got it under control. I think Barth should have stuck a little placard on the dash with instructions.

The idea of driving down the road spilling fuel overboard conjures up images of fire trucks and hazmat teams and EPA SWAT teams and black helicopters and ......oh well.

If you have smog inspections, be sure to have the right tank selected.

quote:

I think Barth should have stuck a little placard on the dash with instructions.

Amen to THAT!......In retrospect, over the past three years, I wonder how much fuel I've vented overboard......

At any rate, the mystery now appears solved, thanks to this thread.....I don't have a malfunction, I have a designed-in idiosyncrasy. Just gotta learn to live with it........

As always, thanks to all......

In the computer biz, this is not a "bug"; it's an "undocumented feature"!

It's great the mystery has been solved.