Ford F150 Fuel Pressure drops fast

[Jimmy]

Heey Guy`s

I got a little problem here.
my fuel pump was bad so i replaceted and also the fuel filter.
Now the enigne idles rough, and the when I put the ignition in the ON position the pressure only go`s up to 20 psi and will drop to 10 psi.
When i start the car the pressure will go to 50 psi but shaks a bit and when i shut the engine of the pressure will drop to 20 psi again and drops to 10 and holds it there.

Did i not install it correctly of is there somting els going an?

I’m sorry for the misspelling i`m

Car :

Ford f150
Build: 2000
Engine: 4.2

Topic

[Jimmy]

oke so when I use my phone its not posting my comments

So I dont now whats happening right now
the fuel pressure holds but it will still drop when i turn of the key the pressure will drop 20 psi and then it will hold on to 30 psi

now then I driving down the road and I let of the gas somtime it will stall the rps will drop to around 500 rpm and then its just stalls while driving.
then I turn the key and it will start right up

I have no idea what it is

[cj1]

Fuel pressure at idle should be around 40 psi. If you remove the vacuum hose from the FPR, pressure should increase maybe up to 50 psi.
This checks if the FPR is indeed working.

[Jimmy]

Yes it did. it shaks a bit but it works

[cj1]

Do you have a scanner to read live data? If so post both St and LT fuel trims at idle and at higher RPM 3000( hold for 1/2 min or so to give LT time to adjust)

[Jimmy]

OK I’ll try that and I will post tomorrow

[Author]

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