Is it really full ?
In another thread I described how our tank was plumbed, with the vent and fill hoses drooping well below the top tank level and full of fuel. My tank is airlocked. For fuel to enter via the filler hose, air in the tank has to bubble thru the vent hose loop intead of just having the air flow out the vent tube. With the engine running the lift pump is strong enough to suck some air into the tank through the same vent hose so the fuel keeps flowing to the engine. Plus most of the fuel comes back to the tank via the return line anyway.
What I'm getting at is if yours is the same way, it may not actually be full when you think it is. When I fill the tank, it can overflow and only be half full. To check you can slowly remove one of the fuel gauge screws on the tank top immediately after it's been filled. First, there shouldn't be any air hissing in or out. That was the tip in my case. Then you can dip one of those long wooden skewers in the screw hole and see just how high the fuel level is. You might be surprised.
In another thread I described how our tank was plumbed, with the vent and fill hoses drooping well below the top tank level and full of fuel. My tank is airlocked. For fuel to enter via the filler hose, air in the tank has to bubble thru the vent hose loop intead of just having the air flow out the vent tube. With the engine running the lift pump is strong enough to suck some air into the tank through the same vent hose so the fuel keeps flowing to the engine. Plus most of the fuel comes back to the tank via the return line anyway.
What I'm getting at is if yours is the same way, it may not actually be full when you think it is. When I fill the tank, it can overflow and only be half full. To check you can slowly remove one of the fuel gauge screws on the tank top immediately after it's been filled. First, there shouldn't be any air hissing in or out. That was the tip in my case. Then you can dip one of those long wooden skewers in the screw hole and see just how high the fuel level is. You might be surprised.
Richard Elliott said:Unfortunately, I tested our 1989 E34 the hard way by running out of fuel. Attempts to bleed and prime by filling the fuel filter at the dock on the level were not successful, supporting the totally empty of usable fuel theory. Refilling completely to overflow (whoops - I thought it held 30 gallons!) took 22 Gal.
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