Rear Windshield Wiper Wash Pump

Hello, I have a 1999 Ford Explorer with 137,500 miles with the SOHC 4.0L engine. I have been having problems with the rear wiper and rear washer. I have fixed the rear wiper by taking the motor apart and cleaning out the grease and it works fine. The problem is when I press the washer button no washer fluid comes out. My washer fluid for the front wipers works great but nothing for the rear. Any suggestions? I have tried to test if the hose was plugged only from the back not from the front. Any other suggestions?
Thanks,

Bryan