Need help with Charcoal Canister please.

[UMDSmith]

Okay, after searching on here and reading everything about the charcoal canister, most people say they just remove it, and cap the incoming vacuum line to the upper intake.

I did the same thing, I capped the vacuum port that goes to the charcoal canister on my cobra upper. I removed the canister, and I left the fuel line open so it vents to the atmosphere.

Now it idles fine (minus another small problem I need to fix) but when I accelerate hard, or reach a higher rpm at speed, the car bucks and stutters.

My theory is that the car expects that extra air from the charcoal canister at higher rpms, which causes the computer to send a signal to that valve that is in between the canister and the intake, that opens the valve and lets a draw through.

Is this theory correct, and if so, how do I fix my issue while keeping the charcoal canister off. Do I just re-add the check valve and solenoid yet let the hose draw from open air, and keep the fuel line sit open.

In summary:

What is the proper way to remove that canister and deal with both the vacuum line and fuel line.

**NOTE** There are no emissions on the eastern shore of MD, so that is not a concern.

 

[UMDSmith]

bump

 

[jd351]

Look somewhere else for the source of that problem (fuel pump or filter?), because removing the charcoal canister is not the cause. This is only purged at startup, then the purge solenoid is closed all other times. BTW, If your leaving the vent hose on, I would add a fuel filter to it just to keep any moisture, dirt, or insects from getting into the fuel system- no joke.

 

[UMDSmith]

The bucking only started when I capped that vacuum line, which is why it has to be related to the change. Unfortunatly leaving the line open at idle causes the engine to vibrate and buck like a mofo, so much so that I didn't drive it with the open vacuum and capped it.

 

[UMDSmith]

Also, mine wasn't purged at startup, I did some tests on the vacuum with the purge solenoid attached, and on startup, the hose at the canister experienced no vacuum draw, unfortuantly I can't hold my finger over it while driving to see if it opens up at speed.

 

[90mustangGT]

I think you are having some other problem that just sprung up when you did the canister. Make sure you didn't break anything or leave anything disconnected. I agree, I would make sure the gas tank isn't just open all the time.

Thanks UMDsmith, gave me an idea. I woul just get a little breather filter and rig it up. You want the tank vented so it doesn't end up pressurized or vaccumed, and a small filter would vent it but help keep things out and vapors in. Never thought of that, but it makes commone sence.

 

[jd351]

Leaving the line open creates a large vacuume leak and this of course causes bucking, it's a lot of un-metered air. The problem you are having sounds like a lean condition, are you sure there isn't a vacuume leak? Posible the plug/cap you use on this is leaking? Or, maybe you had something else come loose while working on this line? Do the usual vacuume leak check, you may find the problem this way.

 

[UMDSmith]

I'm fairly certain it only is this line, mostly because the bucking when this is capped only comes into play over 2500 RPM.

Here is something else I just considered. Could my fuel pump be on the way out, and since the old charcoal canister was clogged anyways (never getting vacuum) it presurized the tank, causing the pump to not have to work as hard? Now that it is an open system, the weakness in the pump is showing up and causing a lean condition??

Its a stretch, but I know for a fact I don't have any other vacuum leaks, and there is zippy chance I messed up anything sans the charcoal canister. Mostly because where it plugs into the upper, pulling it off really doesn't hit anything, so no accidental bumping and such, plus both the a/c and s/c parts on the tree are capped snugly.

I also am certain the cap is on well because an open vacuum at idle there causes a visible rough idle, whereas once it was capped, the idle was fine. It only got rough again under heavy accel, or breaking about 2500 rpm. Which was never a condition before. I will put a filter on that open line though, to keep debris out of the fuel and preserve my fuel pump. Thanks for that suggestion.

Judging from everyones posts, it seems like everyone who has removed the canister capped that line to the upper intake and had no problems.

 

[jd351]

Well it's a stretch to think this was the last nail in the coffin for your pump, but I have seen weirder things happen... and many of them were an untimely demise of a fuel pump.

Nothing like replacing a (know) bad TFI and having the engine not run afterwards, only to find the fuel pump gave out right then (no joke, happened to my neibor) or doing a clutch replace and having the pump fail, happend to a friend. The pump was still pumping, just week, ran very lean and we thought we must have pinched a fuel line, but after looking it all over we pulled the line from the filter- just dripped when pump was running. New pump and problem solved! So, yeh it could have struck you just like that.

 

[UMDSmith]

Hmmm, that may be it, its making a different whine now then it use too. Anyway to easily diagnose a crap fuel pump?? I think Ill re-hook the purge solenoid just to test its opening and closing.

 

[jd351]

Best way I know to check fuel pump is with a fuel pressure gauge, but if you don't have one, you can disconnect the fuel line at the filter, then turn the ignition switch to the on position (do not start). Fuel should squirt out like a garden hose for a second or two (pump will only run for one to two seconds, this is normal), if not, then the pump is bad. BTW, you can have volume without pressure too, so B4 you disconnect it do this: Turn ignition on and off a couple of times (do not start motor), then go to the schrader valve (looks like a tire valve on the fuel line near Cylinder 1) and depress the valve, just like letting air out of a tire. It should spew out fuel and relieve a lot of pressure.

 

[HISSIN50]

on the line of diagnosing FP:
a gauge on the schrader valve is the easiest, IMHO.
if lacking pressure, it is likely the pump itself or the regulator. crimping (carefully) the return line and checking things out is a way to further diagnose between the two.

good luck.