Need instructions for 94 XLT purge valve

[Dennis94XLT]

I found my fuel vapor canister purge valve isn't working and the engine compartment has a strong gas smell coming from the vapor canistor. I verified the vacuum line is not broken (I can't blow through the line going from the canister to the valve with engine on or off). There is no vacuum there with the engine running either and I think there is supposed to be vacuum to clear out the vapors in that canister.

The valve itself is under the intake manifold and looks like a major job to change but I haven't tried it and am waiting for the part to arrive (mail order from a discount Ford dealer).

This is a 1994 XLT explorer with A/C and standard equipment. Does anyone know how to change this valve without taking the intake manifold off - and - is there anthing else I should replace while in that area as preventative maintenance? The truck has 94k miles on it.
Thank you for advice on this replacement.

Dennis

 

[duckdog27]

I just replaced the canister purge valve on my 94 XLT. To remove it without removing the upper intake I unhooked the vacuum connection from the throttle body (drivers side on the throttle - removing air intake tube to throttle body makes removing it much easier). I pulled the canister very carefully towards the drivers side below the egr vacuum sensor. There is a long electrical connection to it so it should come out far enough to unhook the connection. The other vacuum tube to it attaches to the canister on the driver side fender. Unhook that and take the whole assembly inside. Use a blow dryer to heat up the nylon connections and carefully twist them off. If you break the nylon t-fitting, don't worry, because the replacement valve comes with the fitting, but be sure not to break that! Boil some water and stick the ends of the vacuum tubing in the water and then attach to nylon fittings on the new valve. Didn't take too long. Good luck.

 

[Dennis94XLT]

Replacing valve

Thank you for the instructions. I will try it exactly as you suggested. I have one other question - I read another post where a guy said these always stick open. Mine is not open - I think it's stuck shut. Was yours stuck open or closed?

Here's a tip for you. The website http://www.fordpartsonline.com is where I get parts. They are always 20 to 30% less than the local Ford dealer and they are a real Ford dealer in Texas. You can order on-line or you can call. I got the part for $36.00 and it's the OEM part.

Would you replace the EGR valve at the same time (sounds like it's in the same area) - I know those clog up after a while.

Thanks again - I really appreciate the advice.

 

[MrShorty]

1st thing I would do is determine if the CANP valve is really stuck closed. Not having vacuum at the cannister does not necessarily mean the valve is stuck closed. The CANP valve is normally closed at idle, and the computer chooses to open the valve when it chooses. Most important thing it looks at is RPM (Waits to be above ~1500, but there could easily be other things that go into deciding to open the valve). Easiest way to check operation of the CANP valve:
1) Enter EEC-IV output state test mode. Since you have to go through the KOEO test in the process, watch for a KOEO CANP code.
2) With your vacuum gauge/pump on the hose leading to the valve, see if it holds vacuum.
3) Switch the solenoid by pressing the throttle and see if it changes.

If you can see the valve open and close this way, then the valve is working properly. This doesn't eliminate the possibility that there is an intermittent fault that causes the valve to stay closed sometimes, but it does indicate that the valve can open and close.
If you don't see the valve open, then you need to determine why -- is it mechanically stuck? Is it not getting power from the EEC relay? Is there a bad connection between the valve and the PCM? Is the PCM bad? Electrically, the circuit is pretty basic and pretty easy to diagnose with a voltmeter and a wiring diagram. If the circuit is intact but not being controlled, that could point to a bad PCM (that's where mine is at. Can't seem to convince myself I have a bad computer, but everything points to a bad PCM).
Distinguishing a stuck valve and a clogged line could require a little work, since those hoses don't always like to come off of the valve cleanly.

I can't stop you from just replacing the part and seeing if it fixes it. But I would sure hate to spend $36 on a part to find out that $0.36 worth of solder and electrical tape would have fixed the real problem.

 

[Joe Fast]

I am having a similar problem with my 1999 SOHC; however, I do not get the smell but the check engine ligth comes on. The Snap-on scanner read no current codes at the time of the scan but the following codes and descriptions were in memory: p1450-Unable to bleed fuel tank vacum, P0171 System too lean Bank 1 and P0174 System too lean Bank 2. We checked the gas cap with the inspection machine and found it to fail twice. Bought a new cap and tested it to be fine. Replaced the cap with the new one. It ran fine for about a day and then the light re-appeared... Any thoughs?


JOE

 

[MrShorty]

Joe Fast: I have no experience with EEC-V. That said:
Did you clear the codes after replacing the gas cap?
What codes come up now?

 

[Joe Fast]

I cleared the codes and the same ones re-appeared one day later. I was under the car and saw that the two hoses feeding the canisters come off the top. Would it be safe to assume the valve was in the tank?


JOE