Can't Seem to get Check Engine light to Stay Off - Ranger-Forums - The Ultimate Ford Ranger Resource


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Old 11-16-2014
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Can't Seem to get Check Engine light to Stay Off

Alright, I have one thats been stumping me for a while. I have a 1995 Ranger and the check engine light keeps coming on with the error code P1443 (low / no flow was what the ODBII computer was saying) which goes to the evap system. After doing some research, I replaced all of the hoses, sensors, and canister and still no luck. Then I took the bed off of the frame to get a better look at the gas tank and found that the fuel filler hose had some good sized cracks in it and replaced that one as well. I'm pretty sure I have replaced every part in that system now and the CEL is still coming on with the P1443 code, any ideas on what it could be causing it?
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Old 11-16-2014
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check the fuel rail pressure regulator , it may be stuck fully / partially open

also replace the rubber hose to the regulator
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Old 11-17-2014
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What year Rangers use a fuel pressure regulator? I know Ford stopped using this method at some point (maybe not in the Rangers?), as it helped to prevent the fuel from vaporizing in the fuel lines. They went to a single fuel line (no return line to the tank), and "turning on, turning off" the fuel pump based on fuel rail pressure.
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Old 11-17-2014
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1995 was the last year i believe

but RON D can chime in as he would know more about the exact year
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Old 11-17-2014
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Yep. RonD for Ranger president!
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Old 11-17-2014
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Where is it located? I can't seem to find it.
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Old 11-17-2014
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the pressure regulator if it is equipped with 1 , it should reside on the fuel rail close to the fire wall
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Old 11-17-2014
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2000 Ranger has a returnless fuel system, so no pressure regulator.

The code P1443 is usually an EVAP canister sensor problem, located in drivers side front of engine compartment usually, not sure on 2000.
Canister may even be back at the fuel tank now.
Leaking filler neck or bad gas cap would be another code, but still good to fix the filler neck.

The EVAP "flow" sensor should be in the engine compartment.
The way the system works is that the EVAP flow sensor is on a vacuum line from the intake manifold, there is also a computer controlled valve on this same vacuum line.
When the computer opens the vacuum line the sensor detects the "flow" of air in the vacuum line.
Code P1443 means that "flow" was not detected.

So you have a vacuum line like this:
Intake manifold----------Sensor----------Valve----------canister-----fuel tank.

If the intake line had no vacuum then there would be no "flow"
If the sensor was bad it wouldn't detect flow, check electrical connector
If Valve was bad it wouldn't open so no "flow"
If Canister was blocked then no "flow"

The valve is just a 12volt solenoid, so you can test it using battery power, no power = closed, power = open, you will hear it click.
And you can test it with vehicle at idle, if you power the solenoid you should have vacuum all the way back to the fuel tank.

P1443 is no "flow" detected, so if you have "flow" all the way back from the tank then either the sensor is bad or the sensor wiring is bad or the PCM is bad

Now a long shot would be the PCM itself, not sure on the 2000 model but at some point in the early 2000's Ford moved the PCM connector to the upper center of the firewall, turns out that was a goof.
Water can get into the connector at that location causing all sorts of odd issues, they added a cover to the connector once enough problems were reported, lol.
So disconnect battery(VERY IMPORTANT)
Then unbolt PCM connector and have a look at the connection, clean and dry is what you want to see.
With connector off you could also test the EVAP flow sensor wires, see if they ohm out, no shorts or breaks
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Old 11-17-2014
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Thanks for the reply, I am having the problem with a 1995 not a 2000. Are the systems the same or different?
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Old 11-17-2014
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Oops ...........

Yes, should be pretty much the same EVAP system, the parts are all the same, they can change the order on the vacuum line, i.e.
Intake manifold--------canister----sensor------valve-------------gas tank

You would have a fuel pressure regulator(FPR) on a '95, FPR wouldn't cause that code though, P1443 is an air flow code.
FPR is on the fuel rail it will have a vacuum hose attached, just FYI
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Old 11-18-2014
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I checked all of the components and they all look good. Any other ideas? I checked the PCM connector as well.
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Old 11-18-2014
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I had perhaps a similar problem with my 08 Rangers evap system about 3 years ago. Took it to the dealer about 4-5 times. Each time they'd replace another part (including the gas cap on about my 4th trip as they had no other ideas) and after about a week the CEL would come on again with the same codes. Finally, on my 5th trip to the dealers they finally found the problem: a couple of wires in a connector, I think in the engine compartment had shorted out. After they repaired that, I've never had the problem again.
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Old 11-20-2014
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I have to ask this: are you one to "overfill" your gas tank? In simple terms, do you stop filling when the gas nozzle clicks off the first time at a pump, or do you continue to "top off" the gas tank by squeazing the handle a couple of extra times?

I had a 2005 Ford F-150 that I did this to for about 5 years of ownership. I eventually got an EVAP CEL code (can't remember the number), and it ended up being the canister. The Ford tech told me to NEVER top off a fuel tank, as the overflow of fuel can slosh up the filler neck and work its way to the canister, effectively plugging it up. The canister is supposed to capture gas tank fumes, and allow them to be reburned (travel to the intake).
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Old 11-20-2014
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I can't say that I do top it off, I typically only fill it to about 3/4 of a tank.
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