Pretty sure I know the issue here, but wanted to see if anyone else has had the same experience:
Backstory: I have a 96 GT with 106k bought from a private seller about a year ago. 28 years is a lot of time for shenanigans, so I won’t go into what has been done to this car. All in all it’s been very well maintained, though there are many original parts that are on life support.
Judging from the carbon build-up on the plugs and O2 sensors, The vehicle runs very rich. I’m getting codes on all four O2 sensors (P0135, P0141, P0155, P0161). I did all the diagnosis of the heater elements and electrical back to the PCM. All of those things check out.
Issue at hand: Low fuel pressure.
What I’ve done:
Next I did something I should have done before loading up the parts cannon, and that was test the fuel pressure upstream of the fuel rail. Primed the fuel pump and my pressure gauge immediately jumped to 30psi. Primed a 2nd time and it jumped to 38 or so. Started the vehicle and pressure held steady.
So … Bad fuel pressure regulator? Some other restriction within the fuel rail system? I inspected the regulator and found that 1. The o-rings and gasket were trashed, and 2. The damn thing is bent! Looks like someone didn’t seat it flush before cranking down the bolts with an impact driver, causing it to bend. See photo. Thankfully it didn’t bend the mating surface on the fuel rail. Surprisingly there isn't any fuel leaking from this gap, nor is there any fuel leaking from the vacuum stem.
I’m going to replace the regulator anyway, but wanted to share this in case anyone else has had the same/similar issues and if this fixed it.
Thanks!
Backstory: I have a 96 GT with 106k bought from a private seller about a year ago. 28 years is a lot of time for shenanigans, so I won’t go into what has been done to this car. All in all it’s been very well maintained, though there are many original parts that are on life support.
Judging from the carbon build-up on the plugs and O2 sensors, The vehicle runs very rich. I’m getting codes on all four O2 sensors (P0135, P0141, P0155, P0161). I did all the diagnosis of the heater elements and electrical back to the PCM. All of those things check out.
Issue at hand: Low fuel pressure.
What I’ve done:
- Checked the pressure at the schrader valve. On prime, I was getting a whopping 4psi. No, not 40. 4! When I started up the vehicle the needle slowly climbed up to 30psi.
- I then removed the vacuum line from the pressure regulator and the psi rose to 40psi. Replaced the vacuum line and it went back to 30. This is what it’s supposed to, so I assumed the regulator was doing its job. Right? RIGHT?
- I wasn’t able to pinch off the return line as it’s nylon or some other hard substance.
- This lead me to believe it was a bad fuel pump. I dropped the tank and pulled out the pump, and I’m glad I did. It looked nasty, and possibly the original Ford unit.
- I replaced it with a Delphi unit as well as a new Motorcraft filter.
- I also removed all of my fuel injectors, cleaned them up, and replaced their o-rings. All injectors ohm tested between 14.9-15.1 ohms, and had clean spray patterns.
Next I did something I should have done before loading up the parts cannon, and that was test the fuel pressure upstream of the fuel rail. Primed the fuel pump and my pressure gauge immediately jumped to 30psi. Primed a 2nd time and it jumped to 38 or so. Started the vehicle and pressure held steady.
So … Bad fuel pressure regulator? Some other restriction within the fuel rail system? I inspected the regulator and found that 1. The o-rings and gasket were trashed, and 2. The damn thing is bent! Looks like someone didn’t seat it flush before cranking down the bolts with an impact driver, causing it to bend. See photo. Thankfully it didn’t bend the mating surface on the fuel rail. Surprisingly there isn't any fuel leaking from this gap, nor is there any fuel leaking from the vacuum stem.
I’m going to replace the regulator anyway, but wanted to share this in case anyone else has had the same/similar issues and if this fixed it.
Thanks!
Last edited: