Poor fuel delivery from Auxiliary fuel tank

[Bear]

Hi I'm Bear and have a 1977 Ford chassis Coachmen Leprechan. it has the 360 with 112k on the odometer. it is very sound mechanicwise when I drove it home I discovered a problem with fuel delivery from the aux. gas tank. with the main tank it runs like a "Bear" but it spits, sputters, loses power, and backfires when using the aux. gas tank. it has 80% fresh fuel with 93 octane and a can of gas dryer, it did no good. is there a separate fuel pump for each tank? could it be a problem with the switch over valve? with the Aux tank it runs fine, as long as it is at idle. any ideas? the only other problem is an exhaust doughnut at the manifold on the pass. side
the interior just needs some updating with cushion recovering, a good cleaning, and checking to see what all works.
Thanks in advance for all your help.


Bear

[HandyDan]

From the sounds of things, the first thing I would look for is a rotten fuel line from the aux tank.  It sounds like it is getting air in the line.  If it still has original lines from the 70's I am sure they are cracking by now.  You probably have a mechanical fuel pump on the engine that pulls from either tank.  There is a possibility that an electric fuel pump was added somewhere near the fuel tank, but I doubt it.  I'm betting on the rotten fuel line.  At least it is an inexpensive item to fix.  Or, now that I think about it, you might have a fuel filter that is clogged coming out of the aux tank.  Some of these fuel filters are hard to find.   

[DaveVA78Chieftain]

I agree.  Old rubber line at the tank sucking air instead of gas.  Just went through this on my 78 Chieftain.  If there is no access cover to the tank from above then you will have to drain the tank, drop it and replace the rubber fuel line.  I was lucky, was able to transfer gas from one tank tothe other.  Oh, if the hose for one tank has gone bad, the other is soon to follow.

Dave

[Froggy1936]

RE : Acess to tanks can be very well hidden. On my Mini Winni I have to remove the rear table leg socked on the floor to get to the sending unit Or remove the tank  Frank

[Bear]

Thanks guys, I will certainly look at them first and check the main tank while I am at it.  again Thanks, your help is greatly welcomed.