How to replace fuel pressure regulator

Hello, I have been unable to find you a good step-by-step from anybody I know. What I would recommend doing is trying one of the auto parts stores online. You can both buy the part there and get some good instruction on how to install: http://replacement.autopartswarehouse.com/parts/autopartswarehouse/wizard.jsp?year=1991&make=FO&model=F150-CST_2WD_RC-001&category=All&part=Fuel%20Pressure%20Gauge&dp=true In addition, the fuel pump regulators in 1991 F150s have been troublesome. If you want to go the safest route, you could bring to a mechanic for a relatively inexpensive fix (part is not expensive, and it should not take them much time at all to swap it out). Best of luck! CarGrrl

Your fuel pump relay is stuck.This should take care of the continuous running but your fuel pump may be bad too since you have no pressure it may have worked the pump to death and possibly blown the diaphram in the regulator.