Jump to content
Ultimate Subaru Message Board

Did I Kill My Charcoal Canister??


Recommended Posts

In the process of swapping a SPFI ea82 engine into my 86 wagon I carelessly hooked up my fuel lines wrong and pumped fully pressurized gas into the evap line of my charcoal canister. This resulted in fuel pouring out the hose that comes out the bottom. I corrected my lines and went on to other things.

Now I’m at the testing stage and have driven the car twice for a total of 14 miles. 12.7 for the first test drive. The first time I test drove it, the car did really well for a while. Then it started to bog down and loose power. It kept up like this until I got it home. I assumed this was due to the fact that the car was originally carbureted and doesn’t have fuel tank baffles, and that I didn’t have a full tank and was sucking up air. Filled up the tank most of the way and tried again a couple weeks later. 

This time the car acted very similarly, but didn’t make it as far before the same issues began. I got out and noticed that at idle the charcoal canister was dripping fuel. My dad was in the car with me, and has a bit more experience around older cars and said it seemed like the engine was flooding based on the drivability. 

What I know this could be: 

•Bad sensor input to ECU (CTS, MAF, O2, etc)

•Blown FPR, which I doubt because it’s not a consistent issue, ie I have to drive a bit before it’ll start acting up

•EGR valve stuck open or bad solenoid

•Bad injector, which I also doubt because it’s not a consistent issue

Since the car is preOBD it makes the diagnostic process more difficult (for me at least) and I’m having trouble pinpointing my issue. Any help to point me in the right direction or links to threads with similar discussions are appreciated!

Link to comment
Share on other sites

Charcoal canister is over 10,000 days old, many charcoal filters have 60 day replacement intervals. 
I would assume it was already dead or this is unimportant. 

Have you tried to read the codes?  You should be able to get it to flash the codes - I'd do whatever you can to do that.  On XT's there's an LED in the ECU which flashes the codes if you follow the directions.  Does SPFI do this? 

 

Check codes

Ignition is all good - plugs, wires, cap, rotor?

Check timing belt - verify timing is exactly right (the alignment marks are opposite of EJ and people mess that up sometimes)

Verify you're getting enough fuel (particularly if the car sat for a long time - bad gas, rusty tank...)

Verify the lines are properly hooked up - triple and triple check again if it's already been wrong. 

Check vacuum lines - make sure there's no leaks (spray starter fluid/carb cleaner)

 

Link to comment
Share on other sites

32 minutes ago, idosubaru said:

Charcoal canister is over 10,000 days old, many charcoal filters have 60 day replacement intervals. 
I would assume it was already dead or this is unimportant. 

Have you tried to read the codes?  You should be able to get it to flash the codes - I'd do whatever you can to do that.  On XT's there's an LED in the ECU which flashes the codes if you follow the directions.  Does SPFI do this? 

 

Check codes

Ignition is all good - plugs, wires, cap, rotor?

Check timing belt - verify timing is exactly right (the alignment marks are opposite of EJ and people mess that up sometimes)

Verify you're getting enough fuel (particularly if the car sat for a long time - bad gas, rusty tank...)

Verify the lines are properly hooked up - triple and triple check again if it's already been wrong. 

Check vacuum lines - make sure there's no leaks (spray starter fluid/carb cleaner)

 

After the first test drive I checked for codes as per the factory service manual (no codes reported), but will check again to make sure. 

I’m confident in my ignition system as the car runs great until driven, no misfires, proper idle, returns to idle after revved weather hot or cold. 

I’m confident in my timing as well for the same reasons. 

Since the issue only occurs when driving, how would I test if I’m getting enough fuel? I’ll check the location of the lines as well. 

Vacuum sounds promising though... I grabbed my EGR and purge solenoids (I think that’s what they’re called: the emissions ones shown in the sticker under the hood) from another spfi so it’s possible I grabbed a bad one. I’ll check for leaks as well. 

Much thanks!

Link to comment
Share on other sites

Okay I actually skimmed your first post and didn't see symptoms clearly. 

if it's running fine until it's up to temp then i'd check the vacuum leaks, MAF, O2 sensor, and keep checking for codes or wire in a way to easily see if the check engine light ever comes on. 

Edited by idosubaru
Link to comment
Share on other sites

29 minutes ago, idosubaru said:

Okay I actually skimmed your first post and didn't see symptoms clearly. 

if it's running fine until it's up to temp then i'd check the vacuum leaks, MAF, O2 sensor, and keep checking for codes or wire in a way to easily see if the check engine light ever comes on. 

Just went and messed around with it a little. 

Started up great, no hesitation. When I pumped the gas a little and let off the idle dropped to about 700rpm as if it was warmed up, even though I had just started it, and slowly rose up to about 1500rpm where it stayed. If I revved it a little it would repeat that process until it warmed up a little, and it would only rise up to 1000, then finally to 700 and would rev normally. 

Once it was warmed up I got out and there was gas on the ground under my charcoal canister that wasn’t there before. It wasn’t dripping, so I set my camera up and got in the car and revved it a bit to see if that’s what triggers the fuel being dumped. No dripping at all... weird.

Then I did the starter fluid trick and could find no evidence of a leak, but noticed that if I pump the brake the engine stutters a bit, which leads me to think it’s vacuum even more

Link to comment
Share on other sites

Poked around in the FSM some more and narrowed down the dripping fuel a bit. The charcoal canister is connected to the fuel separator, which sends it gas fumes/vapor. If the separator isn’t working, could it be sending liquid fuel to the canister which is dripping out of the hose on the bottom? I also noticed that my EGR and purge solenoids get really hot... don’t know if they’re supposed to.

Under what conditions does the purge solenoid vent the fumes into the intake manifold? If there is excessive fuel in the charcoal canister and the purge solenoid is allowing it into the manifold, could that be causing my drivability issues?

Link to comment
Share on other sites

If you block off the brake vacuum booster port on the manifold do the brake pedal press symptoms stop?

Don't drive until reconnected or you may not be back in here.

Thinking a vacuum gauge for diagnostics may be helpful.

They are the olde worlde tune up machine if you learn to decipher them.

Fit a clear PET drink bottle in place of the charcan for diagnostic purposes lol

And for this post let us know if driving or stationary

Using the word runs nice does not tell us if you have road load going on 

Did you get to test drive the donor as spfi at all?

Maybe these symptoms why it was parted?

My first EFI was EA82

My first turbo was the same EA82 :)

it "ran" well stationary, it drove well until I asked of it - just 2nd gear would be nice....so only drove nice, low speed, first gear, 50 metres

i T'eed in a fuel pressure gauge to see the pressure at 36 psi all while stationary revving. Driving was different, fuel pressure gauge taped to outside of windscreen dropped to 10 psi before I could get out of first of three auto gears

 

Edited by Step-a-toe
Link to comment
Share on other sites

41 minutes ago, Step-a-toe said:

If you block off the brake vacuum booster port on the manifold do the brake pedal press symptoms stop?

Don't drive until reconnected or you may not be back in here.

Thinking a vacuum gauge for diagnostics may be helpful.

They are the olde worlde tune up machine if you learn to decipher them.

Fit a clear PET drink bottle in place of the charcan for diagnostic purposes lol

And for this post let us know if driving or stationary

Using the word runs nice does not tell us if you have road load going on 

Did you get to test drive the donor as spfi at all?

Maybe these symptoms why it was parted?

My first EFI was EA82

My first turbo was the same EA82 :)

it "ran" well stationary, it drove well until I asked of it - just 2nd gear would be nice....so only drove nice, low speed, first gear, 50 metres

i T'eed in a fuel pressure gauge to see the pressure at 36 psi all while stationary revving. Driving was different, fuel pressure gauge taped to outside of windscreen dropped to 10 psi before I could get out of first of three auto gears

 

The symptoms I reported in my original post were during driving conditions, but my more recent comment above was while sitting. 

Ive been planning to get a vacuum gauge set and fuel gauge set, but just haven’t gotten around to it. Looks like the time has come.

I’ll try blocking the booster port and see if that symptom goes away. If it does it would mean a bad booster hose, hose connection to booster/manifold, or bad booster correct? I can’t really see any way the symptom would persist with it disconnected and the port blocked.

Will you explain why having a clear bottle would help me diagnose? I’m open to it, just don’t understand it lol

Edited by G3.Spiffy
Link to comment
Share on other sites

Only got to drive the donor once but the symptoms weren’t present then, and it wasn’t driven conservatively. The previous owner had documents showing a complete engine rebuild, and had been driven for multiple thousand miles (don’t remember exactly) since then. They got in a crash and sold it to me. Had it trailered most of the way but I live off grid and drove it the last ~10 miles with no issues. It did awesome actually! 

Im pretty sure that whatever’s going on was somehow my doing.

Link to comment
Share on other sites

So I just went and started up my dads 92 spfi wagon and it does the same thing with the brake stutter. I’m gonna assume it to be a slow reaction to a change in vacuum and keep troubleshooting my drivability and fuel dripping issues for now

Link to comment
Share on other sites

A couple things -
The CTS can fail in a way that doesn't cause the CEL to light up, or generate a code -  Causes weird idle speed variations, and some poor drive ability issues. 

If the fuel pressure drops below 21 PSI for a SPFI, it will get very messed up - can't get any power, poping  unsteady running.

The solenoids run hot.  The EGR solenoid - during warm up, it disable the EGR Valve.  That's it, that's all it does.  I have never had any drive ability issue from that solenoid's most common failure mode, which is the coil burns out failing open.  And the ECU code 34 is displayed.  I never had as much trouble with the purge solenoid, so I don't know how much it can mess with anything.  The canister may not do it's function, but mine are all 30 years old +/- and the cars run fine.

Link to comment
Share on other sites

That clears some things up for me, thank you. CTS and fuel pressure testing are at the top of my list. I’ve heard of people deleting purge and EGR systems and am curious if deleting them temporarily would let me know for sure if my issue lies with one of those systems, and if so, how would I go about that? Just plug the lines that go to each system at their extremities? 

There has been a decent amount of fuel coming from the hose at the bottom of the charcoal canister intermittently (more-so when driving), and it seems like it’s abnormal to me. To test this I removed my charcoal canister and plugged the vacuum line, put the input hose (fuel separator to canister) into a clear bottle to track its fuel output, and plugged the line that goes from the canister to the purge solenoid. Ran the car for a while (parked) and there wasn’t ANY fuel in the bottle, which is the opposite of what I expected.

I have another charcoal canister laying around that I can swap in to see if it changes anything. Considering that I pumped high pressure fuel into the one that’s currently in it, I don’t think it could hurt. My dad thinks the canister is heavier than it should be as well, which made me consider that there could still me fuel in it from my routing mishap that’s just cycling out of it and that’s what I’m seeing on the ground. Still doesn’t explain the drivability issues to me but could be unrelated 

Link to comment
Share on other sites

Charcoal canister is just a red herring. It can be deleted - even if it weren't flooded with gas it's still well past the age at which they are essentially useless. Unless you must have it for inspection reasons - just delete it and cap the vacuum lines to the intake. 

Check your CTS as Dave suggested. 

GD

Link to comment
Share on other sites

8 minutes ago, GeneralDisorder said:

Charcoal canister is just a red herring. It can be deleted - even if it weren't flooded with gas it's still well past the age at which they are essentially useless. Unless you must have it for inspection reasons - just delete it and cap the vacuum lines to the intake. 

Check your CTS as Dave suggested. 

GD

Unfortunately I do need it for inspection purposes, but am not opposed to a temporary delete to see if it fixes my issue. What do I do with the other line( gas tank to canister)? Cap it as well? I’ll check my CTS next time I’m out working on it

Edited by G3.Spiffy
Link to comment
Share on other sites

Sorry, I suggested clear bottle in place of charcan so you can make observation as anything goes in , hook up an outlet hose too? Monitor if any fumes exist or exit?

What's a charcan do? Once upon a time fuel caps were sometimes vented as there were no other vent outlets at fuel tank, just bulk fuel in, and fuel sucked out.

If I capped a charcan I'd need to ensure fumes/ pressure coming off the tank got to go somewhere like the atmosphere, and not anywhere I would smell the fumes as I do now in my XT that is factory, but something is amiss.

All is fine if I drive with windows closed, sunroof shut and recycle air. Also stinks shed out after parking.

I was thinking if clear bottle theory to observe my own problem, share it with anyone :)

Link to comment
Share on other sites

The main idea is that the fuems get absorbed by the charcoal when the car is sitting,  and fuel is evaporating.  When the car is running,  air is sucked through the charcoal into the intake to burn the fumes.   For testing or delete, you want to cap the lines that have vacuum.   Might make sense to try to catch fuel that's coming out there, because that isn't normal.   I'd want to know how / why.

Link to comment
Share on other sites

2 hours ago, DaveT said:

The main idea is that the fuems get absorbed by the charcoal when the car is sitting,  and fuel is evaporating.  When the car is running,  air is sucked through the charcoal into the intake to burn the fumes.   For testing or delete, you want to cap the lines that have vacuum.   Might make sense to try to catch fuel that's coming out there, because that isn't normal.   I'd want to know how / why.

 

3 minutes ago, idosubaru said:

Fuel coming out of that hose is not a common symptom. I’ve never heard of it happening and no one has yet mentioned what causes that so I’m assuming they haven’t either. 

I understand. Went and plugged the lines which go to the throttle body and the purge solenoid, and put the line from the tank to the canister into a clear bottle, ran the car for a while without driving load and had absolutely no fuel in the bottle.

This has me convinced that the fuel I’ve been seeing on the ground is just residual fuel from when I hooked the fuel lines up wrong initially that’s still inside my canister. I’m going to swap in an extra canister and see if the drip goes away. 

Link to comment
Share on other sites

I disconnect the fuel hose at the drivers side firewall and see what it's doing.  It either flows like a garden hose, or nothing, or spits and sputters.  I haven't seen any that have a "low flow" which would be hard to tell by eye. And the fuel test kit I have is annoying to hook up to a Subaru...I mean it's not hard but there's just no advantage to diagnosing for me over pulling the hose.  And it's just fun spraying fuel over a hot engine, gives me a rush.

 

....just kidding, cover it with a towel, etc. 

Link to comment
Share on other sites

19 minutes ago, idosubaru said:

I disconnect the fuel hose at the drivers side firewall and see what it's doing.  It either flows like a garden hose, or nothing, or spits and sputters.  I haven't seen any that have a "low flow" which would be hard to tell by eye. And the fuel test kit I have is annoying to hook up to a Subaru...I mean it's not hard but there's just no advantage to diagnosing for me over pulling the hose.  And it's just fun spraying fuel over a hot engine, gives me a rush.

 

....just kidding, cover it with a towel, etc. 

There are a total of three hoses coming from the drivers side firewall. Fuel supply from the pump, fuel return from the FPR to the tank, and the fuel evap line that goes from the fuel separator to the charcoal canister. I’ve pulled all these and made absolutely sure that they act as they should. I pulled supply first, and there was pressurized fuel in there. Put it in a bottle just to see if it pushed fuel upon prime and it did. Plugged that one back in and pulled the return hose then started the car for a second and it was getting lower pressure fuel coming through it. Then pulled the evap hose and it had no apparent signs of fuel. 

Link to comment
Share on other sites

Decided to blow a little compressed air through the drippy canister while I have it out and it blew fuel all over. Definitely what’s causing the dripping. Swapped in my spare canister (which is in fact much lighter) and ran the car until warm and had zero drippage!!

  • Like 1
Link to comment
Share on other sites

I haven’t taken my CTS out for testing yet, but unplugged it while the car was still cold and after it was up to temp. There was no change in the car’s behavior while parked, which surprised me. Is there any way to test the CTS in place or should I just suck it up and get all science-y with my known temp water?

Link to comment
Share on other sites

Get the engine up to operating temp.
Shut down.

Disconnect the connector.
Connect an ohmmeter to the sensor leads [it has 2 wires].

Watch the ohms.  take note of the hot, and look every 10 minutes or so.   And for a while every so often.  What you want to see is a slow rate of change, not jumping around crazyness.

Somewhere on this forum I have posted some typical numbers and temps.  The exact values are not super critical, but the general slope and smooth change is. 
 

  • Like 2
Link to comment
Share on other sites

21 minutes ago, DaveT said:

Get the engine up to operating temp.
Shut down.

Disconnect the connector.
Connect an ohmmeter to the sensor leads [it has 2 wires].

Watch the ohms.  take note of the hot, and look every 10 minutes or so.   And for a while every so often.  What you want to see is a slow rate of change, not jumping around crazyness.

Somewhere on this forum I have posted some typical numbers and temps.  The exact values are not super critical, but the general slope and smooth change is. 
 

Just to clarify, the CTS is the two wire one with the green connector that’s by the thermostat correct?

The one wire one by it is the signal for the temp gauge and the one on the rad is for the fan relay?

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...