87 Ranger fuel pump losing prime ??

[raggedyann]

87 ranger stx 2.9. I must cycle key on/off several times to start. Doesn't matter hot or cold.
From what I read, sounds like check valve in fuel pump. The fuel pressure regulator isn't leaking when vacuum line is removed.
Ok, it has the frame mounted pump also. So are there a test I can do or to determine if its the in-tank pump or frame mounted one ??

 

[Spott]

There's no check valve in the tank pump, only the high-pressure pump.

 

[raggedyann]

I thought I read that all in tank ones have the chk valve built in , what about the models that don't have the in-line pump ?
or is the high pressure pump only have the valve ?

 

[RonD]

The in tank pump on your year and earlier years was for a carburetor system, 5-9psi pressure, and carbs have float bowls so have a fuel reserve for starting, these types of pumps didn't have or need check valves.

Fuel injection systems have no fuel reserve, and run at 30-70psi pressure, so fuel injection fuel pumps all have check valves.
In your year the fuel injection fuel pump was added in the frame rail, so it has a check valve.
In later years the high pressure pump was moved to the gas tank, and the check valve with it.


Remove the return fuel line on the FPR(fuel pressure regulator), put towel under it, turn on key a few times and if fuel comes out of the FPR replace it, that's your pressure leak.
FPR should be closed tight until engine vacuum opens it.

 

[raggedyann]

thank you, looks like the FPR is the fault. done as instructed and it pours.
so to see if I have a good one.

 

[raggedyann]

I found a spare but its leaking also.

 

[RonD]

Used older ones will probably have cracked seals if they have been sitting dry for a long while.

 

[raggedyann]

the original one is a motorcraft with fitting that takes a wrench to remove and I looked those up they list for a 4.0 I read a similar post where theirs had a 4.0 regulator.
all other 2.9 I seen has the spring clip connect

 

[RonD]

Get the one that fits your return line and fuel rail, FPR is there to maintain 30-40psi fuel pressure, 2.3l, 2.9l, 3.0l, or 4.0l don't matter

 

[raggedyann]

Guys I just don't get it ?? I have tried 4 different used FPR and all puts fuel out the return line by cycling key on/off.
so I order a new one and it does the same.
my son has a jeep samuri and he has put 3 different ones on it and it also does the same.
we know they will put fuel out the vacuum line when theyre bad.
So next step I will change frame mounted fuel pump.