Try replacing a fuel pump.

Massey

 

could also be a failing fuel pressure regulator.

 

yeah I've tested the fuel pressure regulator it dose not seem to leak or anything I guessing it might be the pump is there any way I can check to make sure whether its the FPR or the Fuel Pump?

 

here you go. got this from here,
http://shbox.com/1/4th_gen_tech2.htm...essure_testing

What the factory manual says to temporarily install, is a set of "fuel line shut off adapters" (probably something the normal guy is not going to have available). You remove the fuel lines from the rail and connect these valves in between. This lets you shut off either side of the lines for testing.
You can do the same thing by pinching the flexible lines to shut them off, but risk breaking them. You might be able to do it (your risk) by using a needle nose vise grips and putting some scrap hose as cushions on the jaws. Then use that to clamp off the line just enough to seal it. Obviously, this is not the best way to shut off the lines and could result in breakage. Heat and age can make the hoses brittle. If you don't want to risk it, don't. It's just a suggestion.

i used some cardboard folded over. i also slid the cover to the fuel lines up so i could get to softer fuel line that hadnt been made brittle by the sun and so on. you clamp the return line which is the small one.