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Old 09-06-2014
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Join Date: Sep 2014
Location: accokeek
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low fuel pressure

Good evening folks. I have a 2.5 ranger that has a serious lake of power.

Currently I'm tracing out several things. One I have a lean condition or so the computer tells me. I've cleaned my K&N air filter, replaced my fuel filter, and checked my fuel rail gas pressure which is 42 psi. Not good but not terrible. Should be 60 to 65. Checked voltage going to the pump..12.4 volts. Just for kicks I checked the fuel dampener, and no gas coming out of vacuum port. And noticed a fluctuation in idle almost like a surging. So I believe it is working. I've unplugged my egg and didn't notice a difference warm or cold engine, so that may be my problem. I will replace the egg asap. Can someone he me out. Why the low pressure? is it bad enough to cause the lean condition?
Any help would be appreciated.
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Old 09-07-2014
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Since you can test your fuel pressure then you need to test it after you shut down the engine.
You say it is 42psi with engine running, after you turn off the key watch the pressure, it should stay the same not drop down.

Yes 42psi is low for a '98, too low really, and a problem.

The fuel pump has a check valve built-in that prevents "back flow" when engine is off and also with pump running.
This is the only "fuel pressure" part of the returnless system, damper just absorbs pressure changes when injectors open and close.

There are also fuel line connections in the tank that can leak, this will lower pressure over all.
The fuel filter can effect pressure as well, as it gets clogged up the volume of fuel it can pass is less and less so pressure will go down, for $10 it is worth replacing every 4 or 5 years.

The computer expects 60psi of pressure, it has no way to monitor the pressure.
It opens the injectors for a specific amount of time to add fuel to the air in the intake based on 60psi pressure.
If pressure is lower than say 50psi then computer has to open injectors longer, to maintain correct fuel/air mix(O2 sensor data), the computer has pre-set limits for injector open time, if it reaches that limit and O2 sensor still reports lean exhaust then computer will turn on CEL(check engine light) to let you know there is a problem.

ECT sensor on the 2.3l(not sure for the 2.5l) is located on the drivers side of the block towards the front of the engine, under the intake.
ECT sensor has TWO wires, and tells the computer the engine temp, for cold(choke mode, open loop) or warmed up(closed loop, O2 sensors used)

ECT sensor looks similar to the Coolant temp SENDER, the sender has ONE wire that goes to the dash board temp gauge.
These two coolant temp devices are not connected together or shared.

Last edited by RonD; 09-07-2014 at 09:33 AM.
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Old 09-07-2014
Thread Starter
Join Date: Sep 2014
Location: accokeek
Posts: 2
Ok. With key off gas pressure in the fuel line remain constant 42psi for upto 5 minutes after running the engine.
I meant egr but my tablet auto corrects spelling.
Checked for exhaust leaks before the cat and found a leaking gasket so I replaced it.
No change. Did this a few weeks ago. Still no power.
I guess replacing the fuel pump is next. I've done this before but can't remember how long ago, probably several years. Anyway its not the original. Any other areas I should check?
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