Hey everyone!
I am having problems with my fuel pressure again! I had lost pressure 3 weeks ago! i would only have 10 psi at idle and crusing but other then that it was 0! so i pinched the return line and the pressure shot up to 60 psi. so i installed a new OFV from TRQ TECK. so when i installed it the pressure was at 25 psi at idle and 28 psi at 2500 rpm no load! so i jacked it up to 30 psi at idle and 32 psi at 2500 rpm no load! all is good right! I also got a snubber vavle when i ordered the OFV. so after i installed the OFV and made sure all was good i installed the snubber valve and a new steel braided line cause the rubber hose i had did not look nice! started the truck up and pressure was back down to 27 psi at idle and 29 psi at 2500 rpm no load. so I adjusted the OFV back up to 29 psi at idle and 32 psi at 2500 rpm. took it for a ride and found that the pressure would drop to 28 psi if i got on the truck hard. put a post up on here and someone said it was normal to see a pressure drop due to the IP pump using more fuel! that brings me to now! i was driving home and noticed when crusing at 70 mph the pressure is 29-31 psi if i pull a hill or get into it the least little bit the pressure will drop to 20 psi. i was told it should never drop past 25 psi? so the truck has 178k on it has the stock lift pump and IP pump i just changed the filter in january and have ran 3 tanks of fuel through it so far. do you think the filter is bad or is the Lift pump starting to die on me. the truck was stock till 5 weeks ago when i installed the #10 plate and a 3 gsk spring. any thoughts? should i change the fuel filter agian?

Thanks
Eric

 

The fuel pressure at idle is supposed to be 20 lbs, at 2500 rpm it should be 30 lbs no load. Under full throttle it will go down. I change my fuel filter if the pressure drops beow 15psi at full throttle under load. The difference in pressures you are seeing can just be the snubber smoothing out the reading, I do not think anything changed in reality. If you suspect the lift pump just pinch off the return line again and check it but I think you will find that it is fine. I have the same mods and more that you just did and that is what my readings are. I have about 100 miles on a new filter right now and at full throttle under load I have 22 lbs.

 

OK!!! If you say so!! I really thought it should be higher then that! But hey if it is normal then i am game! When do lift pumps normally give up?
Thanks for your help again!

 

Cummins specs are no less than 18 psi at all times but as said you have to take into account the snubber.
Snubbers make the gauge read slow and may not be showing you the true psi.

 

infidel
do you think i am ok? do you think the pressure is less then what the guage is reading? is there another snubber valve i should buy? when i drove the truck last night it went down to 18 psi at one time!
thanks guys