Washer Fluid Siphons out when tailgate down

I have an '03 Chevy Blazer Xtreme. When I put the tailgate down, the washer fluid is running out the spray nozzle on the rear wiper. It acts like it is siphoning out from the front tank. I have searched the forums and found the 90 degree elbow problem, but nothing describing mine. Both front and rear washer fluid work and spray correctly. It's like the tank is higher and when the tailgate is down, it is acting like a drain for washer fluid resevoir.

I checked to make sure the cap on the resevoir was on correctly, thinking that maybe that with the cap on correctly, it would not allow air into the tank to vent. The cap is on correctly, but I'm not sure it was designed to be air tight anyway.

Any help or ideas would be greatly appreciated.

Thanks....Lael Fitzgerald

I have seen one of these leak from the pump but still pump fine. No the system is not designed to be air tight.

Check your check valve. There should be a check valve in the line for the rear washer, and I pretty sure it is under the hood by the washer tank. Good luck.