well I am guessing I can post this here. my fuel pressure has been going crazy the past few weeks along with the weather outside. normally the pressure is in the 12-13 psi range after the fuel filter. but today like others it was all over. down to 3 psi down to 0 psi at idle and a revs, then after 3 hours of the truck running its back in the 12-13. NOW I don't want to listen/read you all to tell me to change the lift pump, so NOBODY SAY THAT. what I am thinking that eather a few things like the fuel in the line for the gauge is semi gelling. or the tank is frosty like, just thinckend and as the truck warms and the fuel returns to the tank it heats/sturs it up. yes I am running addative and all that good stuff. the truck gets parked out side in a apt lot too far from any outlet to plug in. the weather has been all over the past few weeks up 50f down to 5 degree days of a max of 16 degrees. it just seams the pressure stays up once the fuel is a little warmer. And all you guys out there said I didn't need a rv tank heater on the fuel tank. ps it's 4.5 degrees out now and droping fast

 

i'd put some kerosen(sp) in the tank to see if it helps or some anti gel. or you could check your fuel filter.

 

It sure sounds like a lift pump. I would verify the guage as being correct first. Is the guage mechanical or electric?

 

It's the lift pump. Cold weather took it out.

I know you didn't want to hear that, but it is fact. Get a FASS II or a Walbro set up. Don't replace junk with junk.

 

I said I don't want to hear that and it's only been on there 4 months. I also forgot to add that there is No power change what so ever as the fuel pressure varys. and when I disconect the pusher lift pump. the truck sputters and bairly idles so the pump is working. the gauges are 6 months old and mechical, autometer with no isolator. I talked with a few diesel guys around here. and they said our pumps just got #1/winter blend and since we got this low sulfer junk. that no addative is in there. maybe I will try thining out the mix or heating the fuel tank some time.

 

Denial is not a river in Africa. You are chasing the same problem I had, and I thought I could fix it also. I went through 5 LP's thinking it was something I could overcome. Ain't gonna happen. Your stock LP is already shot, the internal check valve for the pressure regulator is damaged, or stuck.

These pumps can be bad right out of the box. Pressure is pressure, makes no difference if the fuel is #1, #2 or some blend in between, or water. Trust your guage, your fuel pump is bad.

Try this just to humor me, I would hate to see you burn up your $2,000 IP. Replace the LP with a new one. I'll bet your pressures are just fine, and this will buy you enough time to replace the POS stock LP with a FASS II or Walbro. If this doesn't work and your pressures and still bad, at least you have a back up pump.

 

I agree. Better to be safe than sorry!

 

I had the same identical problem 2 years ago when it got cold, crazy pressure readings. Check valve is messed up in the pump.
I had 214,000 miles on that pump - the original.
I replaced it with a one from O'Rileys, lifetime warranty.

 

My last lift pump I replaced (from Napa) lasted 5 months. If you don't believe your lift pump is failing, test your fuel pressure with another fuel gauge. If you have a gelling problem, add some anti-gell additive to your fuel tank and drive around for a little bit. If your fuel system is operating well, it won't take long for the additive to circulate through the system.

Have you open up your fuel filter and looked at it????


Hope you get this worked out!!

Joe

 

We just had this blast of cold weather come through Oklahoma a couple days ago, I filled up at a station that truckers use and asked the people running the station if the fuel was winterized? Their repy was they owned a diesel pickup before and as long as I plugged in the engine heater I would be fine! I went and doubled up on the Power Service and added a couple gallons of kerosene to be safe.
A gelled up fuel system is no fun - been there done that.

 

fuel filter is one month old and only has about 800 miles on it, but I will take a look at it in the nexted few days. I am ordering 2 more pressure gauges for the truck. on will be installed on the prefilter outlet the nexted on the post filter outlet. the gauge that is on the inside of the truck is feed off the elbow going into the injection pump. it's a bit cold to be out there messing around. I think I will add a shot of the diesel 911 emergancy to see if that will thin it out a bit. right now I got the truck pluged in via 150 foot cord. ya ya but you got to do what you got to do.

 

heres my post on the same topic https://www.dieseltruckresource.com/...pressure+crazy
it sucks mine was only 6 months and 10k miles.

good luck, dieselfan.