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

[Richard Kirshy]

Could be a faulty pressure regulator or perhaps a leaky injector

[Jimmy]

Oké I’ll will check that thanks voor the fast reply

Also I wanne add that the short fuel trim in bank 1 and 2 are around -20

And when I hit the gas it go’s without any problem, but when I let of the gas and it idles again it almost shutoff around 500 rpm

[Richard Kirshy]

If STFT is negative (-) 20, they system is removing fuel which could indicate leaking injectors.

[Jimmy]

so this is what my spark plugs look like
and das that mean that there is only 1 injector good ?

Attachments:

• thumbnail_IMG-20170109-WA0010.jpg

[Richard Kirshy]

Those plugs do not look well at all.
With out knowing the service history it would be hard to tell.

[Jimmy]

https://www.youtube.com/watch?v=zfR-b6W52VM

I know have the intake maniflod removed and clean up the the injectors
still the pressure drops what can it be now ?

[Richard Kirshy]

Maybe a faulty check valve in the fuel pump.

[Jimmy]

On a new fuel pump ? There is no other explanation for this problem ? I’ll go check on this problem but that’s not explaining the stft of -20

[Richard Kirshy]

Did you check to see if any injectors were leaking with the ignition on?
See if this helps:

[Jimmy]

Yes I did and it wasn’t leaking

[cj1]

FPR can leak fuel thru vacuum hose to intake causing over fueling.
Was FPR tested/changed along with new pump?

[Jimmy]

Yess I will check that and no its not changed

[Jimmy]

yes I did and there was no leaking

now i checkt the FPR and I pulled the FPR out it was real durty but its doing his job
because when I unplug the vaccum line and looked at the fuel trims there was no change
i was driving around for a while and suddenly the engine stalls. but it started right up again when i turned the key.

Im now thinking of the o2 sensor can that be durty ?

[Richard Kirshy]

The O2 sensor has nothing to do with loss of fuel pressure.
You need to isolate where the leak is occurring.
Again, I suggest you watch the video below:

[Jimmy]

Ow I forgat the pressure is beter it still drop about 20 psi but it holds around 30 psi for a while

[Author]

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