Windshield washer fluid

[LMP]

'93 Transport:
Windhield washer fluid has always been taken down from full to the level of the rear window pump, even if I did not use any of it. THis happens only when driving long distances at highway speed. THe fluid tank has been tested over and over again as leak proof.

My theory - that I will test starting from now - is that the pressure vacuum created at the rear of the car at high speed siphons the washer fluid through the rear window washer nozzle. So I have dead ended the rear pump outlet and I'm waiting for the results to show now. I'll post the conclusion. Notice that because I had the well known "windshield wiper syndrome" (that I'm taking care of now with the great help of this forum), at times I had disconnected the electrical feed to the pumps in case some freak contact would have activated them without my knowing...to no avail .

I was just curious to know if anyone has also experienced that problem.

[formulaross]

Had a '92 up to 256K miles and never had this happen.