Dinner

I tried searching for a topic close to mine but didn't find it, maybe I just missed it but hopefully you fellas can help me out. I noticed lately my FP has dropped a bit, no biggy so I bought a new filter today and replaced it tonight at the end of work. My pressure really hasn't changed that much that i've noticed...however my gauge has been acting up ever since I changed the filter tonight. I changed it like any other time, primed the filter and away I go. Before though, when i turn the key to on and the LP started, the gauge would jump to about 11-12.5 within a blink of your eye. Now it slowly goes up to about 11 Psi, probably takes a few seconds actually. It also drops off real slow after the truck has been shut off. Where before it would drop right to 0 once the engine was off. I am thinking that there is a lot of air in the line (I could see bubbles when I changed it), and my line was kinda lose so I tightened it up a lot on top of the filter. Could it be the air in the lines, or I tightened the fitting too much and am pinching the hose?

I am going to fiddle around tomorrow morning and see what I can find before I head to work...

Thanks for any help!

Craig

Sask

Could be the check ball valve in your lift pump. They often fail, and when they do, the ball bounces in and out of its seat, resulting in erratic fuel pressure - slow build-up, high pressure at speed, low pressure at idle, etc. If so, replacing the lift pump fixes the problem - until the next time it happens.

Dinner

Hmm the lift pump is only about 10,000km old. The pressure doesn't bounce around at all while driving, and the PSI seems the same as before while cruising. I'm just wondering why all the sudden after the filter change. I'm going to bleed the hose tomorrow to the gauge, well get most of the air out and losen the fitting a bit and see what happens. It's just bugging me cause i dunno why its doing this.

JD730

Its possible the new pump is starting to do it already, I had one with about the same mileage that was relocated with a Vulcan kit do the same thing. Put a Walbro in there and no more problems.

Dinner

I am going to go outside and fiddle around right now to see if I can find the problem, whether in the gauge or the lift pump.

Dinner

Well I bled the fuel hose going to the gauge and the PSI has gone up a bit, pretty much back to normal running PSI. The PSI seems to be climbing quicker at start up and is a little faster falling off at shut down. Im thinking that yes my LP is going out, or when I cranked up the little fitting on top of my filter, I tightened too much and maybe began to close up the end of the hose, causing the slow dropping of PSI at shut down, due to the fuel can't escape as quick...
I will keep monitoring it and saving up for a Holley Blue or something

Thanks Guys

smokinstrokes99

i checked all fittings for leaks or clogs, and checked my guage with another then droped the fuel tank to check the fittings there, then i used the bracket from the lift pump and mounted it to the fram rail, then added an extra fuel filter just for peace of mind then finaly figured out the lift pump was bad so i replaced it today with a true cummins pump ($160) and it idles around 14 like it should and i hope it will last me for awhile. so def. relocate the pump and keep the filter changed

Dinner

I forget what make my LP is, I believe it is a Carter? but I can't remember from when I replaced it. My FP jumps around a little every now and then, but only a .25-.50 change in PSI, it only seems to do it under idle (only in park/neutral). I'm not sure if my LP is dieing, or its just the pulses from it, because my FP is the same as it was before when I had a new Filter in it. I'm thinking that I may get a Holley Blue soon and mount that to the frame as a pusher pump to the stock LP. Maybe that will run a higher PSI?

EDIT: Just been doing some more reading, and as Sask said all along, maybe it could be my Check Valve pouncing around in the LP? If so that can lead to earlier VP death, so maybe it's time to get a new LP. What are some good choices guys? Or would it be good to run just a Walbro down on the frame?

nickg

Any chance its a crappy new filter?

smokinstrokes99

your pres. looks fine, what was the out come on the air bleeding?, what ever the outcome you should mount a new pump on the frame rail as an aux or a single pump. holly blue, walbro, bd they are all good but i saved alot of money by going down to the freightliner dealer and buying a cummins lp

99globalwarmer

pro comp of ebay for like 60 bucks. 16 psi idle wont go below 12 full throttle. lasts a long time. its a copy off of holley pumps. pm me for more info.

http://cgi.ebay.com/ebaymotors/Pro-C...spagenameZWD1V

Dinner

My pressure hasn't changed at all since the new filter, the gauge just bounces around a tiny bit every now and then. Like it's around 12-12.5 at idle in park or neutral...goes to about 13 in gear and idling, cruising is around oh 10.5-11.5 and WOT drops down to 7.5-8. I'm thinking I may keep this pump in that spot, and buy an aux and mount it on the frame. I'm assuming this would be a good idea....have the aux pushing fuel to the stocker, and then the stock one pushing to the VP. I'm going to keep my lines stock for now, so I wont be changing those yet.

Thanks for all the help guys, I was all worried that something may have gone wrong with my truck and mess it all up

Craig

Dinner

If you don't mind me asking, how much was the Cummins one, and what is the difference between it and a Carter? I read somewhere that the fittings are metric on one and SAE on the other?

And so I don't have to start another topic and make people angry with all my posting. I finished installing my Pyro today, drilled and tapped into the manifold "section" closest to the front of the truck(stock manifold). Is the back section of the manifold better to read off of than the front? I went with the front due to my rear section before the turbo being fairly cracked

smokinstrokes99

it ran around $150 for the cummins, and i have heard that the rear of the manafold is better for an accurate read, but not worth re drilling, im still working up the courage to drill around the turbo

Dinner

I drilled mine with everything intact. Just used a good rill bit, had it a little smaller than the probe threading so then when it was tapped it would be a nice snug fit. Then I just made my mark, started to drill...put grease over the area...drill some more, wipe clean, more grease, drill, wipe clean...ya get the idea,lol...until I was through. Took my little retractable magnet and moved it around and to my surprise I hardly had any shavings. So then I tapped it, took the magnet out again to make sure no big stuff got down in there, and away I went with the installation