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Unread 11-05-2013, 06:29 PM   #1
Misterzingle
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Howell tbi charcoal canister bypass

I'm currently installing a Howell tbi, and I guess the charcoal canister was taken out for some reason. Do I need to put a new one in, or is it needed at all?

If it isn't, is there a way to bypass the canister?

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Unread 11-05-2013, 10:05 PM   #2
CSP
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The charcoal canister's purpose is to vent the gas tank and to store gas vapors to be burned when the engine is running. You'd be wise to re-install it.

If one isn't there you pretty much already have a bypass.
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Unread 11-06-2013, 08:19 AM   #3
Misterzingle
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When I got the jeep, the fuel return line had been taken off and plugged. There was also no charcoal cannister. And they don't seem to be produced anymore, and a used was seventy dollars.

So if there is a way to bypass this with the Howell tbi, I'd like to get an idea of how?
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Unread 11-06-2013, 08:39 AM   #4
Matt1981CJ7
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I'm with CSP on this, you really should use a canister, unless you like your clothes and garage to smell like fuel. It's also needed to vent the tank, unless other provisions have been made.

A canister for an early 90's Grand Cherokee ($30) works with a minor modification. That's what I did.

These pics were snagged from this write-up.

Matt
charcole_canister_3.sized.jpg

charcole_canister_6.sized.jpg

charcole_canister_7.sized.jpg

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Unread 11-06-2013, 08:39 AM   #5
CSP
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I'm not sure what you mean by bypassing it with Howell TBI. The TBI has nothing to do with the charcoal canister. If it's not there now it won't be there with the TBI installed.

You will have to run a return line for the TBI, but the return had nothing to do with the canister either. Coming out of the tank in stock condition there would have been a supply line running to the fuel pump, a return line from the fuel filter, and the vapor line to the canister.
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Unread 11-06-2013, 09:10 AM   #6
Misterzingle
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Matt, what was that modification ?

Csp, I was only saying bypass becAuse there was already no canister and it worked, so now that I'm doing the howell, the vacuum diagram says to connect it to the canister.

But I've found one for the cherokee, as long as Matt says it works on a cj7, I'm going to purchase it.
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Unread 11-06-2013, 09:48 AM   #7
Matt1981CJ7
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The "modification" is simply drilling out the two ports on each side of the Cherokee canister, as the middle picture shows.

Otherwise, it fits directly into the original bracket, the hookups are the same, and it functions like the original.

I like the design of the Cherokee canister better because the filter/breather is up top, instead of on the bottom, like the original, where it gets caked with road grime.

Matt
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Unread 11-06-2013, 09:55 AM   #8
Misterzingle
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Well, I'm going to have to fabricate my own bracket, but otherwise I should be good.
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Unread 11-06-2013, 10:05 AM   #9
Matt1981CJ7
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Take it easy when you drill out the plugs. If you're not careful, the bit will "walk" and blow out the side of the port.

I used a standard hand-drill, but a drill press would have been less risky.

Matt
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Unread 11-06-2013, 02:49 PM   #10
CSP
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Glad to hear you're going to add the canister.

The "bypass", since it's vacuum, would be just to cap the line if you weren't going to use the canister. The port Matt's diagram has labeled as Carb is what will connect to your throttle body. The PCV will probably also use this same port, meaning you'll need a T fitting.
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Unread 11-06-2013, 04:04 PM   #11
Misterzingle
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Now that I have your attention



image-2064664557.jpg

This is a fuel pressure gauge that was installed by the previous owner. Is this necessary with a tbi? Can it be removed? Would it be beneficial to install it in line?
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Unread 11-06-2013, 05:33 PM   #12
Misterzingle
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Also, I am finding out I don't have a cto or an egr valve. I believe they are for emissions. Does this change anything?
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Unread 11-06-2013, 05:39 PM   #13
Matt1981CJ7
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I like having a fuel pressure gauge in-line between the filter and carb, or throttle body in your case.

I don't think you'll need the pressure regulator with the TBI.

It's common for guys to strip the emissions systems. Your engine will run fine without the EGR, just not as clean.

Matt
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Unread 11-06-2013, 05:56 PM   #14
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The canister is a passive device in these engines. If you block off the hose to the canister, everything will work exactly as before.

What the canister does is absorb fumes while parked, and feed them back while running. Since there is no float bowl with the Howell, it has even less to do.
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Unread 11-06-2013, 06:29 PM   #15
Misterzingle
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Quote:
Originally Posted by jay-h
The canister is a passive device in these engines. If you block off the hose to the canister, everything will work exactly as before. What the canister does is absorb fumes while parked, and feed them back while running. Since there is no float bowl with the Howell, it has even less to do.
What would you recommend doing if I have no cto, egr, or canister?
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