Fuel pressure issue

[Viva*the*Ranger]

Hey folks! It's been a while since I posted, but I was hoping to pick you brains.

My fiancee has a 2001 Ranger 4.0 4x4, 152k miles, and no records of fuel pump or filter replacements. It's been having trouble starting, so I figured it was fuel related. I had her prime the line by turning the key forward a couple times before starting it for about a week. That worked, so I went and bought a fuel pressure gauge. Sure enough, it registered about 2 PSI on the first prime, and 20 PSI on the second prime. I started it, and it registered 67 PSI (right where it's supposed to be)

I replaced the filter hoping that would do it, and it helped tremendously. It now registers around 50 after priming it. That's not an exact figure, cause I don't have her here to turn the ignition for me, so I have to jump out of the cab and check. There is a certain amount of PSI lost in those few seconds.

My question for you is; since pressure is correct during operation, but low upon priming, does this indicate a bad (in tank) fuel pump? I'm assuming the high pressure pump is good, given the operating PSI is where it's supposed to be.

We're getting married on July 19th, so we're trying to spend as little money as possible. Thus I would like to replace only one pump, and not both! What is your opinion?

Thanks in advance!

Regards,

Chris

 

[RonD]

Could be two things, assuming MPG has not dropped dramatically, and you don't smell gas anywhere.

In either case you must get to the fuel pump.
So remove the bed or drop the tank.

In the fuel pump is a check valve(backflow preventer), if this starts to fail system pressure will drop when engine is off(fuel pump off), it is not a separate piece, fuel pump must be replaced.

Second reason could be a leak in the fuel line IN the tank, just a small one, but when fuel pump is off fuel pressure drops as fuel leaks back into the tank

 

[adsm08]

Dude, you know you only have one fuel pump on that truck, right?

Sounds to me like the check valve is shot.

 

[RonD]

Oops, missed that part, what he ^^ said

2001 Ranger has the "Returnless" Fuel system, and only 1 in tank fuel pump, 65 psi average pressure

Older Rangers with return line had average pressure of 45psi, and some had 2 fuel pumps, these also had a fuel pressure regulator on the fuel rail, "returnless" does not

 

[Viva*the*Ranger]

Could be two things, assuming MPG has not dropped dramatically, and you don't smell gas anywhere.

In either case you must get to the fuel pump.
So remove the bed or drop the tank.

In the fuel pump is a check valve(backflow preventer), if this starts to fail system pressure will drop when engine is off(fuel pump off), it is not a separate piece, fuel pump must be replaced.

Second reason could be a leak in the fuel line IN the tank, just a small one, but when fuel pump is off fuel pressure drops as fuel leaks back into the tank

Thanks for the info Ron! I appreciate it

Dude, you know you only have one fuel pump on that truck, right?

I didn't, but now I do! Thanks

 

[adsm08]

Yeah, 88 was the last year for two pumps. That's how Ford did twin tank fuel systems early on. When they ditched that as an option on the Ranger in 89 they went to a single pump in the tank.