Fuel pressure

[03wr250f]

I recently installed a 6.9 90* fitting with the nipple off of my fuel filter housing and ran a line to a fuel pressure sensor to get my reading for fuel psi after the filter. basically to make sure the ip is getting good psi.
I am getting 4-4.5 psi at idle and anytime I rev it up say to 2500 and hold it I drop to 2 psi. Why, What am I missing?

 

[79jasper]

If your pump is turned up, that seems to be about normal.

Sent from my SAMSUNG-SM-G890A using Tapatalk

 

[IDIoit]

all youre seeing is pressure,
when the pump is pulling it, the pressure drops.
mine does the same.

think of it like a garden hose with a hand nozzle on it.
when you pull the handle the pressure in the hose drops dramatically.
but the volume is still there.
on a old hose, when you let go of the handle, you can see the hose swell because of the pressure.

remember, theres pressure, and then theres volume.

 

[KZF250]

on a old hose, when you let go of the handle, you can see the hose swell because of the pressure.

He was asking about fuel pressure not about what you did last night.

Sorry...couldn't resist.

 

[IDIoit]

 

[icanfixall]

You have plenty of pressure feeding your injection pump. The reason you see a drop in pressure when the engine uses more fuel could be 2 different reasons. One is the filter might be dirty. Two is the lift pump might be getting weak if you still have a mechanical lift pump. I don't think you have a fuel suction line restriction if someone comes up with that possibility later in a post.

 

[03wr250f]

well I still have the mechanical lift pump with maybe 12k miles and 1.5 years on it. the fuel filter is a hastings 15 micron the one mel recommends with his injection so I do know that it is a really good filter but with a filter if its filtering finer that in my book means a bit of a restriction. Also running a baby moose.

side note what do you guys see for coolant temp. I ran 190+- all the way up to maybe 200 no hard pulls or hills on my short drive

 

[icanfixall]

If Mel suggested a fuel filter he was telling the truth. Personally I use the factory Motorcraft filters for both fuel and oil. The work very well. I realize I can run a finer fuel filter but its going to plug up faster. So far I have seen only one filter plug up. That was more than 300,000 miles back. I had just purchased the truck and about a month later I saw the dash light slowly light up and slowly dim out under hard acceleration. So I changed out the Fram fuel filter and never looked back. I probably have 4 years on the filter on the engine now but its only about 45 thousand miles so far. I don't drive as much as I like to drive the rig. I have too much fun driving my rig and the grin is way too long on my face after I park.. Wifey probably thinks I'm doing something that she will not approve of. We wont tell her....

 

[03wr250f]

I see 4 psi driving all the way up to 2300 rpm and after that it starts way dropping off. I have seen down to a half psi at 3000k rpm. is it time to take and go to a facet duralift pump? or what are your guys thoughts? because idiot is saying he sees the same thing but I thought the ip had to see 4 or better psi in order to work? what are your thoughts.
and if you guys think it is time for a electric fuel pump which is best the facet duralift 40222 9-11.5 psi or the facet 40285 4-7 psi im leaning towards the 40285 but idk because that seems like what we need but im curious as to whether I will see the same drop as the rpms increase or if it will be able to sense lack of pressure and produce more to compensate. if someone could show me what I am missing that would be great. thanks

 

[Kevin 007]

That's the same pressure that I have with a mechanical pump. I have no problem with that. If you see 2500+ rpm often and find yourself towing with your foot buried in the throttle a lot, then an upgrade may be alright. Id leave it alone until the mechanical pump dies....sometimes they go for a long long time without issue. Lets hope yours does to.