how to pressure test fuel pump on 1989 k1500 chevy

If your tbi fuel system, tie into the fuel supply line. If vehicle is high enough off the ground, it might be easiest to get under vehicle and remove fuel filter and tie in there. Make sure no pressure before removing filter. Years ago, I made my own tbi fuel pressure gage, I used a gage from air tank, screwed the gage into proper size pipe tee. Used proper hose fittings in each end of pipe tee, then comes the hoses and hose clamps. The id on the hoses was big enough to push over a flare on the steel line. Even with the flare you might use hose clamp also. Pressure for tbi system is around 9--12 psi. Now. if you have mfi fuel system, there should be schrader valve on fuel rail. The fuel pressure gage has a fitting that will screw onto the schrader valve. good luck.

Just to add, with tbi system, I don't like to crawl up underneath the hood and try to work. Actually, I don't like to crawl up under the hood and squat while trying to work on anything, fuel or otherwise. My knees give out. just my opinion.