5.0 Fuel Pressure
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5.0 Fuel Pressure
I have a 99 Explorer that stumbles under hard accelaration, but is smooth throughout the rpm range if I increase the throttle slowly. Plugs are new and coil packs were just changed for the first time at 128,000. The fuel pressure is reading 68 psi. When I unplug the fuel pressure regulator vacuum line the fuel pressure does not change. The vacuum line to the regulator is pulling around 20 psi. Can a bad regulator cause the fuel pressure to be too high? Any other suggestions?
Thanks,
JT
Thanks,
JT
Elder User
Joined: Jan 2004
Posts: 805
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From: Pauline, South Carolina
Yes it can make it run too high. I would assume that the pressure on an Explorer 5.0 should run the same as a Mustang 5.0, which is around 40 psi. If it's not going up when you remove the vacuum line, that's an indication that the regulator is not working. Does it smell rich? If you check the plugs do they look carboned? I would expect both of these conditions with excessive fuel pressure. The sudden rush when you get on it hard may be momentarily flooding it out. Does it give a small puff of black smoke when you do this?
Oh, another thing that could cause the conditions you mentioned is a plugged or restricted fuel return line. Have you done any work around the fuel lines that could have resulted in a kink or other restriction.
Oh, another thing that could cause the conditions you mentioned is a plugged or restricted fuel return line. Have you done any work around the fuel lines that could have resulted in a kink or other restriction.
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The vehicle has been running rich, my check engine light had been on so I assumed it was due to a bad sensor. When I changed the plugs / coils the light went off but the problem remained so I started to suspect something with the fuel delivery. I am going to install a new pressure regulator this afternoon and I'll post whether or not it corrects my problem. Thanks for the comment.
JT
JT
Tuned
Joined: Nov 2003
Posts: 454
Likes: 8
From: CT
Fuel Pressure
My 99 Mountaneer 5.0 runs between 62 and 65psi.
The regulator is just a damper, the fuel pressure is regulated by the ECM and pulses the fuel pump.
They have returnless fuel lines, I don't know if the Stangs do.
68 sounds about normal.
The regulator is just a damper, the fuel pressure is regulated by the ECM and pulses the fuel pump.
They have returnless fuel lines, I don't know if the Stangs do.
68 sounds about normal.
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