Fuel pressure

[braz5711]

Hi everyone
I have a 99 F350 DRW with a 6 speed a few months ago I had the fuel pump go out ever so slowly and it got a couple of injectors and hurt the motor. Instead of rebuilding it I found a 2002 7.3 with only 80,000 miles on it that I got for a good price, so I switched engines and installed a new fuel pump, also before we installed the engine I changed the fuel return spring and housing the spring is a 65 -70. I have also installed a TS 6 POS chip and run it on the 50 hp setting when going back and forth to work. I have a 60 mile each way trip to work. I have also added gauges EGT boost and fuel pressure (don’t want that to happen again) the Engine runs great but what I have noticed is that when running about an hour at hi way speeds that the fuel pressure will start bouncing it will go from 65 to 70 or 80 then jump back to 70 and back up to 80,85, now if I get on the throttle it goes to 65 and holds also if I completely roll out of the throttle it goes to 65 and holds. It only does it when at cruising speed or if I have rolled slightly out of the throttle. Has anyone seen this before and is it a problem? Thanks for any input. Billy

[braz5711]

Bump anybody have any ideas

[BC stroker]

having the same issue right now, My input would be the fuel pressure regulator, Nothing should be able to tighten it up to build more fuel pressure, Less fuel pressure would open up the possibilites to more problems but when were dealing with higher than expected FP then I think its a regulator problem. I am going to install a universal, adjustable myself. Good luck. Remember that high fuel pressures will damage your injector orings and then you'll have a job to do... just did mine less than 1000kms ago.