I suspect that my fuel selector valve is hung-up. Topping-off either tank (2-50's) results in an equalization of tank levels in a matter of a few hours (cross feed flow rate is greater than fuel burn rate)......Gauge still reads accurate.

Life is busy right now, and I'd prefer to wait until end of season to address this. Question:
Am I risking any potential problems down the road if I ignore this anomoly for now?......

On the positive side, the new rate-of-drop of the fuel gauge can fool me into thinking I'm now getting 16mpg rather than 8mpg

quote:

Originally posted by Lee:
cross feed flow rate is greater than fuel burn rate

Nice description, that. In some systems, that is a design goal.

Nah. On a previous MH, on a trip, I replaced a failed Pollak valve with a cobbled-up wye made from local hardware store parts. The only disadvantage was that I could no longer keep a tank of high octane for hills and a tank of regular for the flats.

Consider buying some Red Line fuel system cleaner, and dumping it in when the tanks are low and you will be driving a while. This will assure a concentrated application. Then work the valve a lot as you drive. That could clean things up, if that is what it needs. RL is good, anyway, no matter. Gensets like it, as well.

When you get some time, you might consider removing the valve, capping off the two inlets and filling it from the outlet with Berryman fuel system cleaner and working the valve back and forth electrically. Repeat hourly (or as the spirit moves you) for a day or two, keeping it full of Red Line. Does each tank have a filter before it feeds the valve? That will help keep swarf, crud and detritus out of the valve.

I may be paranoid after 20 years in the automotive business but if it were me I would replace it. Mine failed and I pumped all the fuel from one tank to the other that happened to be full. I left a trail of fuel from the overflowing tank down I-85 for miles. It can be done in your driveway in a couple of hours, better than the side of the road. At least buy one and have it on hand in case it does fail. I replaced mine with two electric fuel pump and check valves.

Neil.

quote:

I replaced mine with two electric fuel pump and check valves.

Hmmmm, in addition to or in lieu of
the engine-driven fuel pump?......pump psi design?

quote:

Originally posted by Neil T.:
I replaced mine with two electric fuel pump and check valves.

Neil.

That sounds like the best way to go. If my cleanout had not worked, I would have done that.

quote:

Originally posted by Lee:
Hmmmm, in addition to or in lieu of
the engine-driven fuel pump?......pump psi design?

In lieu of mechanical pump. I have two Carter fuel pumps with a relay to change between pumps. This relay is also grounded by a oil pressure switch so if the engine is not running the pump will not run. I am not sure it would work with the factory Quadrajet carb but it should. I run a Edelbrock carb. I got the check valves from Summit racing equipment. I can get part numbers if neded.

Neil.

quote:

Originally posted by Neil T.:
In lieu of mechanical pump. I have two Carter fuel pumps with a relay to change between pumps. This relay is also grounded by a oil pressure switch so if the engine is not running the pump will not run. I am not sure it would work with the factory Quadrajet carb but it should.
Neil.

My Barth came factory with a rotary vane Carter pump. Still feeds the same Rochester. They are good pumps. I have had them on a couple of boats, too.

The oil pressure switches fail now and then. If you use one, carry a spare or know how to bypass it. Or both.

I believe the Carter rotary pump comes in two pressures. Pick the low one for the Q jet. Qjets don't like a lot of pressure.

Bill,
The only thing I was thinking about is my P30 came the fuel by-pass system. That system used the mechanical fuel pump and complicated fuel selector valve to return the fuel to the correct fuel tank. I removed both of them. I assume the Quadrajet would be OK with 5-7 psi of the Carter pump but this is all foreign to me, I have worked on imports for 20 years.

Neil.

quote:

Originally posted by Neil T.:
Bill,
The only thing I was thinking about is my P30 came the fuel by-pass system. That system used the mechanical fuel pump and complicated fuel selector valve to return the fuel to the correct fuel tank. I removed both of them. I assume the Quadrajet would be OK with 5-7 psi of the Carter pump but this is all foreign to me, I have worked on imports for 20 years.

Neil.

Yeah, a return system would complicate things a little. A replacement valve would probably be simplest.

My cobbled-together thing was quite a while back, and was done on the road under duress, and I don't remember any return lines, but can't be sure. It was a 1970 (I think) Dodge chassis Newport.

Heck, I don't even remember if my Barth had a return system. In early '01 it got the 502 engine with no engine driven pump. It always passes CA smog, so I guess it is somehow in compliance.

I don't think that engines with carburetors have a return, only fuel injection whether it is TBI or port injection do.

quote:

Originally posted by MWrench:
I don't think that engines with carburetors have a return, only fuel injection whether it is TBI or port injection do.

I'm not sure when it started, but late carb engines often had return lines from the fuel pump to the tank. It was part smog and part vapor lock mitigation.

Here is a post that discusses it a little. I think my previous SOB had it, too. Tomorrow or the next day I will take a look at it if the owner is home. http://barthmobile.com/eve/for...501035803#6501035803

"I don't think that engines with carburetors have a return, only fuel injection whether it is TBI or port injection do."

Ed,
Mine definitely had a fuel return and from what Lee is describing he may have the same system. The fuel pump has three fittings, one to the carb, one from the fuel tank and one returns the unused fuel back to the fuel tank. I think they did this to prevent vapor lock. This requires a complicated valve that not only has to control what tank the fuel is coming from but also must return the fuel to the correct tank. Mine would intermittentley return fuel to both tanks, the wrong tank or not return at all and flood the carb. Not good. I would take this opportunity to replace the valve and hoses. I think the valves are only $80, mine was mounted on the frame between the fuel tanks.

Neil