Fuel starvation, who else?

spearfish25

There is no way the pickup is at the top of the tank. You'd 'run out' of fuel every time you used a few gallons.

Much more likely is the pickup is at the bottom, but either the tank design or the pump internals have a problem with lateral g's. Tank design would suggest all the fuel sloshes away from the pump and the pickup can grab air. Pump design would be more difficult to assign blame (aside from pickup location), but raises my suspicion as the reason when fuel starvation occurs with a full tank. I don't know how a full tank can slosh enough for the bottom of the pump to be exposed to air.

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2013 Cadillac V-Wagon, RIP Z