At the fuse panel, measure the amperage draw with the pump off. It should be zero. If it's not zero, it's possible that some knuckle head at the factory or the dealer tapped the circuit to run something else. Next measure the amperage draw with the pump on. Compare that measurement to the stated amp draw on the spec sheet of the pump. If it's out of parameters, you have a bad pump. If it's not out of parameters, you may still have an intermittent fault in the wiring or an intermittent fault in the pump itself.
Change out the pump. If that solves it, it was the pump. If it doesn't solve it, your problem lies elsewhere.
On edit: it's also possible that the circuit has been fused improperly with a fuse with a rating too small for the pump. BUT, if you suspect that may be the case, do not unilaterally replace the fuse with one of a higher rating. Let the dealer's tech or a qualified expert make that call.