lack of fuel pressure
 

'86 forrunner 22 re 4spd,4wd. after driving for a distance the fule pressure drops so that the engine will not run. have hcanged out the pump already, still have the problem. towed the truck home sat over night, fired right up with 30lbs on the gauge. ran it for a while, drove around the block, pressuer droped to 29lbs. how do I deturmen what is causing the problem, suspect, pump, pressuer reg, or that resister, however I just havent ben able to track it down. any and all ideas are welcome.

When you say Changed out the pump was it new or used?? Bad fuel sending unit that you keep running out of gas?

When was the last time the fuel filter was changed??

I know they say these filters last forever but it is a 86.

Is this a electrical issue that the pump turns off??relay coil dropping out and contacts opening the pump circuit.

Low fuel pressure is either a tired pump or restrictions in the fuel line .

When it quit did it just slowly die or bam just like you turned it off.

pump is new, filter has been changed withen the last three mounths a new filter was also listaled with the pump, tank looked clean. the last time the fuel pressur started droping finley lost pressure alltoghter.

The long "J" line in the pump holder, I have seen get really clogged before on just about every tank I have been into. It is your return line so it shouldnt cause a lack of pressure, but wonder if it could be causing your pump to get hot. It was one of the first things I have had to fix on both of my 88 and my 86 builds.