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How much flow should I get from my gas tank?

Started by hearn, August 19, 2016, 06:43:51 PM

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hearn

My 54 Cadillac md. 62, wouldn't start and run.  I took the outgoing line off the fuel pump and nothing came out as I cranked the car.  There was plenty of time in the cranking for gas to get back to the pump if it wasn't there when I started the cranking.  I am prepared to change the fuel pump (even though this is a fairly recently new aftermarket pump), but before doing so I am checking for a plugged gas line.  I have a ethanol resistant hose for about 1 1/2 feet in the gas line just ahead of the rear wheel.  I used to have an electric pump there.  When I take this hose in the line loose, it is clear from there to the fuel pump, but when I release my pinch on the hose, I get a weak steady stream from the tank.  I'm wondering if this is what it should be or whether it should be a stronger stream.  My previous gas tank even though coated developed a leak on a seam, and I replaced it with a tank bought locally that was very clean inside and therefore I didn't coat it.  I know I have the infamous bullet, but can't remember what is in the tank for filtering, etc.  I really want to avoid dropping the tank.  It is pretty much full of gas.  Any thoughts would be appreciated.  Jim

hearn


savemy67

Hello Jim,

If I read your posts correctly, you have plenty of fuel in the tank and atmospheric pressure in the tank, yet you get only a dribble from the tank through the hose coming out of the tank.  Are you holding the hose below the level of the tank?  If so, it sounds like you will have to drop the tank and check for a blockage at the sending unit pick-up (unless the short length of hose itself is clogged).

Christopher Winter
Christopher Winter
1967 Sedan DeVille hardtop

The Tassie Devil(le)

The amount of flow should be commensurate with the diameter of the fuel line inside diameter that comes out of the tank to the fuel pump.

Any less, and there is a blockage.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

hearn

It is a weak flow not a dribble, but I did expect it to be a stronger flow.  Jim

fishnjim

Depends on the fitting at the tank.   I'm not certain on your year, but some have a flare type fitting welded in for the steel fuel line and the inside diameter is much reduced, say 1/8" and the line is probably 3/8" or 5/16" OD.   
You only need to flow about >6 gal/hr to service the motor/fuel pump output, so take a clean measuring container and your watch with second hand(stop watch) and test the flowrate.   If it starts and stops or varies or less than minimum, suspect some blockage.   Check the vent line too.