dieseldog123

i bought a issopro fuel pressure gauge from genos garage and the billet filter cap so i can run the fuel line off the top of the filter housing my fuel pressure is reading between 8 and 9 at an idle and between 7 and 8 driving and 7 wot is this normal 05 2500++++++++++++++++++++++

RowJ

Will get better response in 3rd Gen Forum!

truckjunkie

With everything stock my gauge reads between 6 and 8 at idle, depending on the temperature of the engine and the outside temp. My gauge is connected via a banjo bolt coming off the CP3 though...

njmaier

I'd say it's normal.

I'm at around 7.5-8 at idle and 5.5 - 6.5 at WOT.

I also have the same setup with the fuel filter cap as you do.

eb290

Just put a Westach setup on today with the tapped banjo coming out the bottom of the fuel filter housing (the clean side) The pressure at idle is 10-10.5 lbs. I had a lot of other things going on today and couldn't drive it any. That will change tomorrow. I tow daily, we will see what the pressures are then.

DmaxEter

All stock for me. Idle is about 9.5psi and when I really ring it out it will drop to about 4psi. Connected directly to the CP3.

eb290

I made a run today of about 375 miles with a light load behind me, about 12,000 lbs including the trailer. As I stated yesterday the fuel pressure at idle was 10 psi. When I started the pressure could be pulled down to 3-4 psi going through the gears, I could pull it to 0 if I went to WOT. Pulling down the highway it ran at about 8 psi going up there on level ground, in the hills it would pull down to 3-4 again. On the way back, the fuel pressure dropped quite a bit. With a 7000 lb trailer and going with the wind it was running at 3-4 psi all the way back and would pull below 0 in the hills. I assume this is because the fuel was heated up. Is that correct? I have seen several comments about temperature. (of the fuel?) This is running an Edge EZ on level 2. I have disconnected it now and will see what it does tomorrow. It will be a shorter run but a lot heavier, probably 25,000 lbs, total load. I have the pump in the tank now, the old one on the block was replaced in Dec.

Geico266

Anything below 5PSI is not good.

no_6_oh_no

....and 0 or below is SEVERELY reducing the life expectancy of the CP3.

N.Johnson

On a 3rd gen stock lift pump 8 psi at idle taken from the banjo bolt is normal and 3-4 psi wot is no problem according to Pier's. The factory manual states 11.5 psi for the stock lift pump but doesn't say where to get that pressure readin from? I'm running the full fass with a 95 gph plumbed to the stock filter and the reading I get at the cp3 tapped banjo bolt is 15 idle/cruise and 13.5 wot. No fueling boxes still stock . I was advised not to run the full fass to the stock canister, but I swear, having the 300 watt fuel heater doing its thing makes a difference. When I first had the fass right to the cp3, it ran great in the summer but winter the cold starts and running was rough and lots of injector noise.

truckjunkie

I guess I should have included the following two tidbits in my original statement:

1) My gauge is tapped into the CP3 with a banjo bolt and then goes through an isolator prior to the gauge.
2) My fuel pressure hasn't changed (usually 6-8) since I installed the gauges about 8 months ago. I pretty much just included the pressure gauge to keep an eye on the lift pump. If it starts acting erratically or drops below 6 lbs. I'll start thinking about replacing it.

big_papa_moo

Do lift pumps usually go out in a flash or is it gradual? Meaning, If I put a fuel pressure gauge on my truck and keep a eye on it, will I be able to tell when and if my lift pump is getting suspect?

I have not added anything to my truck at this point, but don't want to get stuck in the boonies camping with a failed lift pump, or kill the VP44. I also don't have the cash to drop on a FASS at the time, so wondering if I can at least monitor the situation with a gauge.

Say it starts dropping under 5, I make myself get around the money for a FASS system.

fwd talon

i have the 150 gph fass system with filters and im getting 22 psi at idle and around 19 psi at wot.

eb290

Ok, went back to the stock setting today, (disconnected the EZ) like yesterday, everything was fine for a while then the pressure started dropping. I left the house at 5:30 this morning, drove to the location to pick up the tools, I had to load them myself with my winch so I had a lot of idleing. By the time I got back to the yard at about 1:00 it was no different than it was running the EZ on level 2. The slightest hill or pull would peg the pressure below 0.
When everything is cold, the pressure is fine. The longer I run, and I will run the engine sometimes 10 - 12 hrs at a time, the lower the pressure gets. Is the fuel getting hot and causing this? Is the pump getting hot and loseing effiency? This is with a new filter put in yesterday. This is an in-tank pump, put in on Dec.22, last yr. Any ideas?

N.Johnson

Where are you taking that pressurre reading from on your rig. I'm guessing your fass is plumbed directly to the cp3 and your reading pressure from where and with what?