Hey I'm new here and just purchased a 1999 F150 X-cab 4X4 5.4.
Hoping I didn't make a bad purchase because the 170,000 miles on it. I does run and shift great. A lot of maintenance has been done to the truck that is why I decided to buy it. Oh it's an L.A. West conversion truck also.

Anyway, I have been reading and reading up on the P1451 code here and at a few other sites.

I have a code 1451 (EVAP Emission Control System).

I have checked the canister valve and get 60 ohms between the two pins on the valve itself, I have 12+ volts at the red wire connector for the valve, key on engine off. No damaged hoses coming from the tank or going up to the firewall solenoid. What I'm trying to find out is if the solenoid is bad and how to test it. I believe it is the one above the brake booster on the firewall. Looks to have been replaced already with a parts store unit.

I have read and read over and three different F150 forums and cannot find a solution to the problem yet. Any help from you Ford guru's would be greatly appreciated. This is the last code I need to fix so the engine light stays off.

So far I have repaired my intermittent odometer by re soldering the pin on the back of the gauge motherboard, repaired my door rattle by welding the sheetmetal back together for the lock actuator, fixed my Egr code by replacing the DPFE sensor which I just happen to have laying around for a couple years, and have taken care of the rust on the bottom of the doors.

All of this I have done at no cost so far!!!

 

And I also traced the wires for the valve to the wire loom on the frame, they both are in good shape. I even ohm tested them to make sure.

 

P1451 concerns the electrical circuit for the Canister Vent (CV) solenoid. The PCM has determined that it cannot control the solenoid.

First make sure it is plugged in.

If so, unplug the solenoid and check the coil for an open circuit. Coil should be around 50-60 ohms.

Likely causes of error:

Open circuit between the PCM and the CV.

Open CV coil or connection.

Open circuit in VPWR to the CV. Verify this with KEY ON with a voltmeter. Probably a RED wire.

PCM faulty.

Have fun...

The CV solenoid is mount on the canister. The canister is mounted under the body, near the fuel tank.

 

You did read my post right?

 

aaaannnddd cue bluegrass with the answer you need! lol

seriously, wait until he sees the thread. he'll know exactly whats wrong. hes a whiz with these trucks.


so free bump for you!

 

I'm waiting patiently.

 

Nobody have any other ideas or how to test the solenoid on the firewall?

 

project---- gave you the correct answer as well as a reference to consult.
You must do the work to find the problem.
There is no more we can do, but provide the direction you ask for.
Good luck.

 

I guess I'm a little frustrated so don't take this wrong. But in my original post I stated I have tested the solenoid and checked the wires. Everything seems to check out ok. What am I misunderstanding as to the next step? What is the solenoid for that is near the brake booster on the firewall?

 

What pins at ecu do I need to trace back to the canister valve? A wiring diagram would be great. Thanks

 

1999 5.4 Cell 025-004.pdf

The solenoid on the firewall is not relevant to the current fault code.

 

Thanks for the diagram. I am looking to chase the wires to the canister vent solenoid to see if there is a break in the VT/WH wire to the pcm.

I know I have voltage at the red wire back there so I'm thinking there is a bad spot in the vt/wh wire some were.

Where can I find more diagrams like this?

 

I am having a recurring problem with the p0304 code. I replaced the coil and plug but intermittently I have a missfire condition and the only code I get is this one, anyone have any issues like this? I'll be checking the wiring and injector today, how do I know if one is bad?

 

Seems to be a completely different issue, you may want to start your own thread to get some responses.