K 30 P/U 4WD V6-262 4.3L (1985)
Figure No.1 - Inline Check Valve Location
To repair this condition, remove the two screws attaching the washer fluid reservoir to the fender. On the back of the reservoir, remove the check valve
and short section of hose connecting this valve to the windshield washer motor (See Figure No. 1). Reconnect the main washer hose to the washer motor
and reattach the reservoir to the fender.
With the removal of the check valve, a short delay in the delivery of washer fluid to the windshield will be experienced. This delay generally lasts until
the wiper blade is 3/4 of the way up the windshield on the first pass.