F115TLRD fuel pump replacement

[Robertzoo]

Replaced fuel pump and ran like**** only got 28 psi before regulator. Turn key on and get 25 psi from fuel rail for a sec. Then to 0. When running 28 psi
from what I read I need 38 to 40 psi.
changed out fule pump once more and still not right does anyone know the psi on the motor? Going to check psi on this other new on now'
thanks Rob

[boscoe99]

[99yam40]

seems to me there should be a pressure regulator on that rail that dumps excess fuel to control pressure

[boscoe99]

I suspect that there is also.

[Robertzoo]

There is at the top of the rail, next to the port to check the psi.
I tested the other new one with same pis' at top of fuel rail 28 psi and before regulator and got 29 psi.
I did not spend the 500. On yamahas Fuel pump, i bought after market on for$130.00 But part numbers matched up.
so both fule pumps they sent me where bad.
what about what voyage should I have at pump 12v?
thanks for the help'
rob
when unplug vacuum hose going to the regulator, it runs much better but the psi do not change',runs bad when I plug it back in and no chance in psi
thanks everyone

[boscoe99]

Pump running you should see at or near battery voltage. Perhaps a tad less.

[Robertzoo]

When turn key on, should I have a consent psi's and hold it or just get a reading for a sec then go to 0?

[boscoe99]

At key on the pump will only run for a few seconds. Fuel pressure will be greatest then. When the pump stops the fuel pressure will slowly decay over time.

[Robertzoo]

When I turn key on, testing from fuel rail, it jumps up to 25 psi then in two set's back to 0!
when testing the fuel pressure at the port on fuel rail I have 28 psi if I unplug the regulator the fuel pressure does not increase or decrease but the motor runs a lot better

[fairdeal]

Boscoe provided the specification above:
you should see 44 psi;
so either the pump is not installed properly (leaking grommet?)
or perhaps the pressure regulator is bad.
Unlikely IMO that your new aftermarket pumps are 'bad' or unsuitable.

In any case, you need to find out why you don't have 44 psi at key on.

[99yam40]

maybe pressure gauge is not accurate

[Robertzoo]

I'm at the farm today and have a different pressure gauge here I'm going to take and try.
it's odd hooking the vacuum hose going to the regulator it runs so much better

[Robertzoo]

Does anyone know what kind of vacuum numbers I should have? Not sure it help but a have a vacuum gauge I could use?

[99yam40]

I'm at the farm today and have a different pressure gauge here I'm going to take and try.
it's odd hooking the vacuum hose going to the regulator it runs so much better

you have said the motor runs better when you unhook the vacuum line and when you hook it up,
which is it?

you need to find out why you are getting bad rail pressure reading and why the pressure drops quickly to zero

[Robertzoo]

Update, the aftermarket fuel pump that tested bad ,going by psi 's, that I replaced ! It tested 100 psi off boat but could only get 28 max testing it at fuel rail and before fuel rail.
The screen is clean on fuel pump ,changed filter and water separator, fuel hose, plugs and fuel pump and van not get 40 psi's
Any help , I would be thankful for.