Fuel delivery problem

[Rook]

Some History first, I have a 76 Cherokee w a 401 edelbrock man,carter 4 bbl carb There are two fuel tanks with an electric switch (new switch, new fuel pump, filters, and lines from fuel pump. The problum I am having is after about 20 to 30 minutes of highway or city driving, I get a exhaust backfire and the engine dies, if i am going fast enough i can tap the accelator and the motor will fire back up. If I am not going fast enough and the motor dies I try to restart the motor from a stopped postion the motor turnsover but I have found that I am not getting gas to the carb, or for that matter to the fuel pump if i undo the hoses to the electric switch and reconnect the motors fire right up this problum was happing before I replaced the electric switch and fuel pump. I think the problum has something to do with the vapor recovery system but I welcome any information on ideas to help me trouble shoot this problum.

Update 01-10-02
I went on a 400 mile trip this week and experianced the following, While running for approx. 15 minutes at 65 mph. on the main tank the rig exhaust backfired two to three times and the motor died I costed to the side and switched to the auxiliary tank and the rig fired up after about 60 seconds of cranking. I continued driving and after about 10 miniutes the rig backfired so I switched tanks back to the main and throtlled the pedel the engine fired right up and I continued driving. during the rest of the trip I kept switching tanks every 10 to 15 minutes and the problem did not happen. Please give me any Ideas you may have on this problem.
Thanks,

Scott

[ January 10, 2002: Message edited by: Rook ]

[ January 10, 2002: Message edited by: Rook ]

[Rogue]

sounds like you are building a vacuum inside the tank, also check to see if you have the proper gas cap as the system needs to be pressurized to work properly. if that all seems to be fine there might be a "rollover" valve somewhere in the system hanging up - i'm not sure if you have one or not or where it would be. good luck
ps - one other possibilty would be vapor lock are your lines routed close to any exhuast pipes?

[ January 06, 2002: Message edited by: RogueStar ]

[Rook]

Thanks Rogstar, I have two vented locking caps new, and the switch roolover is new I also think its a vacum or pressure problum somthing in the plumbing.

[LHopper]

Hello & Welcome have check the pick up tube in the tank I think there is a screen or a filter on the pick tube, just one thing to check and i had to replace my fuel pump more than once some pumps bad out of the box. ONE THING I`ve done is install a glass fuel filter in line befor the carb.just to help me anytime my 78 dies on me. Fuel or elect. at a glance, and I`ve uesd it more than once.good luck LH.

[Tad]

That thing in the tank at the end of the fuel line is called a "sock" as I was told. Mine was so encrusted with sludge & goop no gas could get through the line except during the early stages of running or when the gas was sloshing around alot.