53 Block King

My fuel pressure has been moving from 16psi to 8 or 9, when it drops I can give it more pedal and it will rise up to 16 again. I changed the fuel filter and drove it for a few days and it continued. So... I put in a new injection pump (blue chip diesel) I have been running on my old pump with multiple death codes for over 17,000 miles so I figured I would quit pushing my luck and buy one. My truck runs better however my fuel pressure is still moving! What causes this? Possible lift pump problem? Why does it raise again when I accelerate? Any ideas guys?

firehawk

Every now and then my pressure will drop from about 15psi to 9psi, as soon as I rap the throttle it will go back up and stay there. Ive wondered what could cause this as well.

slim51015

Sounds like electrical to me. I'd have the batterys and alternator checked. Seems like the more RPMs your getting more voltage to the pump.

caper

Mine does the exact same and I believe its the lift pump, it does it more and more as time goes on and the throtle blip has less effect on it returning to 15 as fast.

micah

mine did the same thing for a couple weeks. It has now moved on to the next stage of LP death in which it runs at about 5-7psi all day, until randomly it decides to wake up and run at 13-14... but even when it is actually running, it is real weak. the slightest bit of throttle can really pull it down.

to confirm it was the lift pump, once while it was running low like that, I shut it down and bumped the starter. nothing. again and nothing. third time was a charm and the LP started to run.

I already ordered a FASS.

bdaniel

Same thing here. Really odd. A new lift pump solved the problem. I also did the Vulcan relocation kit. I'm happy.


Bobby