Occasional Engine surge

[RS Disposal]

2 hours ago, Freightrain said:

15# is about right.

I was having power issues years back and found my lift pump was failing.  I mounted a fuel pressure gauge out on the air cleaner so I could watch it while driving.  It would rise and fall.  Replaced pump and was a solid 15#.  

If you don't have a liquid filled gauge it will flutter due to check valves in the pump.  A liquid filled gauge will dampen the bouncing needle some.

The lift pump is where the plastic check valves are at that was mentioned to check by Terry.

truck seems to run fine around town but when I am climbing the canyon occasionally it will start to miss (more than just loosing power) and I would have to pull over and let it idle for a bit.  Then I could start back up again.  I do understand about a liquid filled gauge, but would think the gauge attached after the secondary filter would mellow the fluttering a bit.  I did notice a couple of times that the gauge did drop to zero for several seconds.  I did pull the plastic check valves and they did look ok, but don't have new to compare against.  Truck only has about 160,000 road miles (not sure about motor miles being there is a pto running a packer) but then again it is 47 yrs old and sat for about 20 yrs before being put back into service about 8 yrs ago.  Truck only really works part time anyway, but I do know stuff breakdown with age alone

[fjh]

14 hours ago, RS Disposal said:

truck seems to run fine around town but when I am climbing the canyon occasionally it will start to miss (more than just loosing power) and I would have to pull over and let it idle for a bit.  Then I could start back up again.  I do understand about a liquid filled gauge, but would think the gauge attached after the secondary filter would mellow the fluttering a bit.  I did notice a couple of times that the gauge did drop to zero for several seconds.  I did pull the plastic check valves and they did look ok, but don't have new to compare against.  Truck only has about 160,000 road miles (not sure about motor miles being there is a pto running a packer) but then again it is 47 yrs old and sat for about 20 yrs before being put back into service about 8 yrs ago.  Truck only really works part time anyway, but I do know stuff breakdown with age alone

Have you checked the tank vent?  And You can actually take the Drainback tee apart and stretch the spring to raise the pressure some 20 25 psi won't  hurt anything!  

[RS Disposal]

14 minutes ago, fjh said:

Have you checked the tank vent?  And You can actually take the Drainback tee apart and stretch the spring to raise the pressure some 20 25 psi won't  hurt anything!  

haven't actually checked the vent it self, but I did try running with the fuel cap loose. I will try the drain back tee and see if it makes any difference. Being a one man show with only one truck and this being my busy season and truck having to also work while I try to figure this out makes for some long frustrating days

[Geoff Weeks]

I had my truck have somewhat similar problem. It was the suction line from the tank to the pump. On hard pull it would draw in enough air to cause a problem, lighter work, it would tolerate the little air just fine. A new hose and the problem was fixed. 

Just something that is easy enough to try, and given the state of the other hoses on the truck, I would say is a good bet. Stratoflex etc hoses don't last forever.