Fuel pressure specifications

Tiny
LEWIS JUDSON
  • MEMBER
  • 1998 FORD EXPLORER
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 102,649 MILES
What is the fuel pressure measured at the fuel rail? I got 30 psi at 20 inches vacuum and 38 psi at 0 inches. With the fuel pump removed from the tank in a bucket of fuel it reads 80 psi. The engine check light is on and it says all three O2 sensors have low/slow response. It has 102,649 miles and the fuel trim is 100%. I suspect the fuel pressure is low.
Sunday, May 23rd, 2010 AT 1:55 PM

28 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
You do not have a four cylinder which one six or eight?
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Sunday, May 23rd, 2010 AT 4:11 PM
Tiny
LEWIS JUDSON
  • MEMBER
  • 2 POSTS
Sorry, I meant six cylinder OHV.
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Sunday, May 23rd, 2010 AT 9:40 PM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Your pressure is within spec. Did you do a volume test? The pump will always put out high pressure when removed, that does away with the regulator that keeps it within spec.
Have you checked for any vacuum leaks in the intake system? Fuel trim may be trying to compensate for a common plenum vacuum leak.
Check the guides below on vacuum leaks and oxygen sensor tests

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor
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Friday, September 21st, 2018 AT 6:44 PM
Tiny
JACKIEG52
  • MEMBER
  • 1 POST
  • 1997 FORD EXPLORER
  • 4.0L
  • V6
  • 4WD
  • AUTOMATIC
  • 149,000 MILES
Vehicle cut out at about 50-60 mph. The cut out is abrupt and intermittent. There are no code from the PCM. Pressure when checked at fuel rail was around 30-32 psi with vacuum, up to 45 psi with vacuum unhooked. Vehicle seems to surge a little bit.
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Friday, September 21st, 2018 AT 6:46 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Fuel should be 30-45 psi with key on engine off. Try a new fuel filter if pressure okay tested like I said. Then clean throttle plate on both sides and IAC hole.
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Friday, September 21st, 2018 AT 6:46 PM (Merged)
Tiny
1WHEELDRIVE
  • MEMBER
  • 1 POST
  • FORD EXPLORER
What is the proper fuel pressure for a 1998 Ford Explorer, 4.0 l, pushrod v-6?
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Friday, September 21st, 2018 AT 6:46 PM (Merged)
Tiny
CATCH_15
  • MECHANIC
  • 250 POSTS
Most fuel injected vehicles need between 35 and 60 psi of fuel pressure to run correctly. Some vehicles will not run otherwise.
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Friday, September 21st, 2018 AT 6:46 PM (Merged)
Tiny
HINOJOSA ELISA
  • MEMBER
  • 15 POSTS
  • 2004 FORD EXPLORER
  • 4.0L
  • V6
  • MANUAL
  • 69,235 MILES
Hello. I recently replaced my fuel pump and regulator as they needed to be replaced. Check engine light and cheà k gauge lights came on. Fuel pressure readings were high therefore fuel regulator and fuel pump had to be replaced. However, driving home truck turned off and those two symbols turned on. Fuel filter was replaced on June of 2013 with 63,000 miles on truck. What can problem be now and can I drive my vehicle as is? Desperate as I need to take my son for his MRI on Monday due to his epilepsy getting worse. Appreciate any answers. God Bless and Happy Father's Day!
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Tuesday, April 16th, 2019 AT 6:40 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
You are going to have to see what code it is that is causing the light to go on autoparts can check it.
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Tuesday, April 16th, 2019 AT 6:40 PM (Merged)
Tiny
HINOJOSA ELISA
  • MEMBER
  • 15 POSTS
Hello. Code read that it was fuel regulator and fuel pump and that's why I replaced those items. Nothing else shows up. If I take it to dealership I'm sorry to say, they are of no help and charge me for other things that aren't needed.
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Tuesday, April 16th, 2019 AT 6:40 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
You still have to do what I said in first reply to see what is wrong.
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Tuesday, April 16th, 2019 AT 6:40 PM (Merged)
Tiny
HINOJOSA ELISA
  • MEMBER
  • 15 POSTS
Took it to see what code showed up. Code for fuel regulator and fuel pump showed up again. Got battery tested as well and it's good.
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Tuesday, April 16th, 2019 AT 6:40 PM (Merged)
Tiny
ONLYBULLSEYES150
  • MEMBER
  • 6 POSTS
  • 2000 FORD EXPLORER
  • 250,000 MILES
What should the fuel pressure be on this SUV. This on is holding on 30 while running.
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Tuesday, April 16th, 2019 AT 6:40 PM (Merged)
Tiny
OBXAUTOMEDIC
  • MECHANIC
  • 3,711 POSTS
Hello,

Ok, there's no Manufacturer Info fuel pressure while running.

The fuel pressure with Key On Engine Off should be 55 - 65 psi
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Tuesday, April 16th, 2019 AT 6:40 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Give us the code numbers
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Tuesday, April 16th, 2019 AT 6:40 PM (Merged)
Tiny
ONLYBULLSEYES150
  • MEMBER
  • 6 POSTS
Ok thanks. I am not, by no means a mechanic. However, someone told me it should be checked while running. I will check it again with only having the key on. Thanks again.
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Tuesday, April 16th, 2019 AT 6:40 PM (Merged)
Tiny
OBXAUTOMEDIC
  • MECHANIC
  • 3,711 POSTS
It should be check before running and while running. It just that on some vehicles the Manufacturer does list the running pressure unfortunately.
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Tuesday, April 16th, 2019 AT 6:40 PM (Merged)
Tiny
CBELCHER2308
  • MEMBER
  • 5 POSTS
  • 1992 FORD EXPLORER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 22,000 MILES
I have a 1992 explorer the factory fuel [ump went out so I changed it then new one lasted about 2 days and the filter cloged up I changed it. Then the pump went out so I put another one in. It worked for 3 days and quit puttin out the rite pressure. The shop said the assembly was bad so I bought a hole new pump assembly and all and it worked for about 3 or 4 days and quit. I changed the pressure regulator the relay and ran injector cleaner through it. Its only putting out 20 pounds and it will start and idle but spudders then dies. To start it you have to turn the switch a few times to build up pressure. What could cause the pump to loose so much pressure?
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Tuesday, April 16th, 2019 AT 6:40 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
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Have the ignition switch tested-could be the injectors are leaking and its losing pressure or a voltage drop problem and the fuel pump is not spinning fast enough to produce the correct fuel pressure-
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Tuesday, April 16th, 2019 AT 6:40 PM (Merged)
Tiny
CBELCHER2308
  • MEMBER
  • 5 POSTS
How do I get the ignition checked?
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Tuesday, April 16th, 2019 AT 6:40 PM (Merged)

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