fuel pressure fluxuating

Decker · Oct 29, 2016

So on my 06 6.0 had a blue spring upgrade done before i bought it and when the truck was cold my fuel pressure sat steadily at 60 psi. When fully warm it would drop to around 50. On hard runs not WOT it would go down to about 47. That scared me a little. So I ordered the accurate diesel adjustable fuel pressure regulator. Love the piece. It is a beautiful work of art. When I first put it on and turn the key over not starting. The pressure was at 80 so I dialed it back far as I could before the screw was up against the radiator hose. I took it all apart and cut two loops off the spring put it back on. This time it was at 70-75ish. So I took it off again and cut two more and back it off till I got it about 65 psi when warm. Truck runs great and sounds good.
I noticed today that cold mornings when I start my truck my psi is at 68-70 until warm then goes down to 65. That doesn't bother me but what does is after my truck sat at work for about 6 hours and when I went to go home (weather outside a out 60 today). I started the truck and the psi was at 55 for about 5-10 seconds before I started to drive then it slowly crept up to 65. Just take off down the road cruising my fuel pressure drops about 2-4 psi and on hard runs my fuel pressure will drop to about 57 psi now.

Should I be worrying or this all normal? Did cutting the spring ruin it. My 04 had a blue spring and it sat strong at 60 psi. Just wanted to try something new. But its starting to worry me a little now.

6.0 Tech · Oct 29, 2016

What pump? Mine was doing this, and the air dog ended up chitting the bed. I can see the factory pump doing the same thing.

Decker · Oct 29, 2016

Factory pump. I hope my pump isn't sh!tin out on me.

Decker · Oct 29, 2016

Did you have all the same symptoms as this?

6.0 Tech · Oct 29, 2016

Search for fuel system issues in the 6.0 aftermarket section. I dont know how to put threads in here. I started that one, and about all the info is in there.

Decker · Oct 30, 2016

Thank you for the thread. Yeah sounds exactly the same. Think I'm gonna try replacing the o rings and gasket on the regulator before attempting to replace the pump. And if I do have to replace the pump think I'm gonna try to hook up a sump feedind a 6.4 pusher pump to the new 6.0 pump

Zmann · Oct 30, 2016

you can buy a OEM Parker pump motor for just over 100.00 in case you weren't aware
you don't need a whole HFCM

i think your cut spring may be a factor ? but your pressures are fine IMO

that cold fuel can really bring the psi up

once you start messing with the OEM fuel system configuration you introduce a lot of potential issues like the poster above had

if you have large injectors you have no choice but for a stock setup I wouldn't be getting all fancy

Decker · Oct 30, 2016

I didn't know that. Awesome! I'll have to look into that. Nice to save a little money. But yeah I think cutting spring did mess it up a little if it isn't the pump. I have read of people who have the adjustable housing putting the the OEM spring back in because the blue spring gave to much pressure. I didn't have one to do so and Accurate diesel recommended the cutting.

Yeah right now I'm stock sticks and turbo. I want to go bigger I'm just trying to get everything prepared before I do. I was losing psi with id x race tune so thought I give the adjustable housing a try.

Decker · Oct 30, 2016

If any one has a OEM spring I would be willing to pay for it and shipping. Just want try that before I go with a new pump

Decker · Nov 1, 2016

No one has a OEM spring laying around?

Decker · Nov 4, 2016

So yesterday I noticed when I rolled my windows up my fuel pressure would drop? I thought the wiring may be bad but my egt guage doesn't change at all. Fuel pressure sensor? Still haven't got a chance to.get a new fuel pump yet so maybe that still might be it. Just curious what anyone else thoughts may be?

Decker · Nov 4, 2016

Forgot to mention all the wiring is solder together and the wiring is tap into the fuse panel under the dash via add a circuit tap.

mandkole · Nov 4, 2016

from your first or second post, I was thinking gauge... whos gauge?

Decker · Nov 4, 2016

Cheap glowshift ... It was a gift. I thought guage too but it worked fine before I up the psi. Then 6.0 tech mention fuel pump which makes sense but now with the window dropping psi idk.

6.0 Tech · Nov 4, 2016

Using the windows has a large draw on the electrical system. You could have a voltage drop somewhere, or the pump may not be running properly on whatever the voltage is dropping to wheen the window os moving.

mandkole · Nov 4, 2016

Decker said:
Cheap glowshift ... It was a gift. I thought guage too but it worked fine before I up the psi. Then 6.0 tech mention fuel pump which makes sense but now with the window dropping psi idk.

Does the pump sound any different? I had a sender go bad on an isspro and it suddenly did all kinds of strange things until it began to just increase. Before I knew it, it was showing 85-90.

Decker · Nov 4, 2016

The pump sounds the same as it always has. I was gonna try to switch the sending unit off my 04 and see if it makes any difference. If it doesnt I'm gonna get a new pump and if it does I'll be calling glowshift.

Still looking for a OEM Spring (not the blue spring) if anyone has one laying around or just have down the spring upgrade.

Decker · Nov 23, 2016

So I put a new pump on today... Yup did not help fuel pressure still drastically dropping . would a street tune draw that much fuel? I have stock sticks and turbo. It sits at 62 at idle but if I give it any petal or take off it down in the mid to low 50. And a all out run in in mid 40.

Air leak? Or worth putting a lift pump on