BB fuel pump/lines

[cheyenne10]

I searched the boards but did not find the explaination for the 2 inlet lines on the stock fuel pump. I beleive on the tank sending unit there are 2 lines leaving tank and both hook to fuel pump. Trying to start truck after an extended period and have uphooked tank and fuel tank switch and trying to pump fuel from gas can. No fuel present yet and carb inlet line. Fuel pump is in tight quarters so R/R is discouarging. Also will be pulling motor for swap after I get it running and compression test and once over.

Also are small block and BB fuel lines the same size on 71/72 trucks?

Let me know what you can.
thanks.

[cheyenne10]

Any help?

[RenoKeene]

If the pump has 2 inlet lines I believe it had an aux fuel tank (like my 72 sb custom camper), not sure what year you have but take a look at the 2 lines comming from your sending unit on the tank, one is smaller than the other. This is the vent line, it runs through the floor along with the fuel line but it runs to a charcoal canister. Hope this helps.

[cheyenne10]

If I traced it right both inlet lines come from tank, 1 supply line and 1 vent. Hoping to use supply line into gas can for soure to start truck. (not bothering with vent line). Not getting fuel to carb so wondering if vent matters or am I seeing things wrong in the dark upside down1

[DANTIP]

There were two pumps available for '72 trucks. One is a 2-line pump and the second is a 3-line pump. I believe the 3rd line on the pump is a vent line. I believe it was necessary for the vapor-control system.

If you are having trouble getting fuel to the pump, I would check the condition of the hoses/lines. Lastly, you could have a corrosion or debris problem associated with your tank.

[cheyenne10]

I tried to eliminate some of these problems by disconnecting fuel line at frame rail and inserting line into fresh gas tank. Only have about 3 feet of striaght fuel line and fuel pump in the way. A little fuel in carb fires truck so ignition system is ok, fuel line at carb is dry. Need to pull pump it sounds like. If I remember there are 3 mounting bolts on fuel pump? I can see/feel the side 2 but if there is one on top I'm in for way more work (factory AC above pump)

My wonder was how this vent line affects the pumps actions.

[DANTIP]

Changing the fuel pump can be a PITA! My recollection is there are only two bolts holding the pump onto the block. Often the cover below needs to be removed in order to put some grease on the pump shaft in order to keep it in the block while installing the new pump. While you have the cover off, you can make sure the old gasket material is scraped clean as well. I have also used a little grease to hold the new gasket to the pump with the mounting bolts protruding a little. otherwise aligning the gasket can lead to four letter words escaping your mouth. I think it's a good idea to replace the two hoses if they are old.

Good luck!!