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Unread 09-10-2013, 06:14 AM   #1
sgtusmc_nc
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fuel smell

I apologize but im a new jeep ower and since im starting my rebuild im sure I will have alot of posts. my jeep a 78cj5 with 304 in it. I notice with the top down there is alot of exhaust smell when driving? the exhaust from the headers back is new, ive crawled it and dont see any holes or leaks. ive owned two classic broncos and never had that issue so im wondering if its because the exhaust pipes dont go out to the side or all the way out the back?

thanks in advance

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Unread 09-10-2013, 06:35 AM   #2
jp360cj
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Where does the tail pipe exit (or stop)?
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77 CJ-7- AMC 360, Edelbrock cam, MC2100, Fenderwells, CJ T18/D20, Chevy D44/EB 9" rear, Trutrac f/r, 4.11, SOA, 1.25 lift shackles, 35x12.50 BFG KM2s, Shackle Reversal
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Unread 09-10-2013, 06:46 AM   #3
Matt1981CJ7
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If the tail pipe (pipes?) exit straight out the back, the exhaust will get caught in the turbulent air directly behind the jeep and will gas you out of the cab.

The tail pipes should exit out the side, into the slipstream, at the rear corners of the tub .

Matt
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Unread 09-10-2013, 06:55 AM   #4
sgtusmc_nc
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I double check tonight but I beleive they stop before the rear gas tank. I know that they dont exit out past the rear of the vehicle. I double check that, and maybe I need to add some pipe and exit it out the rear sides thanks
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Unread 09-10-2013, 08:35 AM   #5
WindKnot
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They need to exit like this:


If they just dump out the back or under the Jeep, the fumes will just get sucked back into the Jeep because of the aerodynamics of our box like vehicles. It's the same reason all the trail dust gets pulled back into the interior.

Also, make sure your gas tank vent is hooked up to the vapor canister. Too many people assume that if it's an emissions device, it is evil and must be eliminated. Not so. All the vapor canister does is pass the fumes through charcoal to eliminate the smell and then pass the fumes back into the carburetor to be burned up instead of stinking up the air. It does not affect the performance of your Jeep. It actually ENHANCES the "chick magnets" that are buried deep inside the chassis. (Little known fact)
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Unread 09-10-2013, 09:49 AM   #6
78RenegadeCJ7
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Quote:
Originally Posted by WindKnot View Post
It actually ENHANCES the "chick magnets" that are buried deep inside the chassis. (Little known fact)
hahahahah
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Unread 09-11-2013, 04:35 AM   #7
sgtusmc_nc
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Awesome thanks
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Unread 09-11-2013, 05:35 AM   #8
JeePete
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sgt,

If you need another reason to get pipes on there to exit the exhaust fumes (besides dizziness), if left "as-is", the exhaust will speed up rust/rot.

It's wet and juicy comin' out, so get it out of there....
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Unread 09-13-2013, 07:43 AM   #9
sgtusmc_nc
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Checked today the pipe(single pipe) exits about 1inch dorectly out the back towards the bumper? I'm guessing that's what's causing the smell? Would it help to have the pipe exit the drivers side behind the rear tire?
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Unread 09-13-2013, 07:47 AM   #10
WindKnot
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YES. That's why I posted my picture. Slipping out the way mine does puts the exhaust outside of the low pressure area and into the slip stream.
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Unread 09-13-2013, 07:54 AM   #11
zillla
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My 75 stinks of fuel every once in while. Like you I have searched for fuel leaks, etc. Exhaust runs out the back as pictured above, cept mine doesn't come out quite as far. It's even with the body. My vent is hooked up to the canister etc. I also have the OEM vented gas cap. Still I smell fuel every once in a while. I traced mine to the exhaust and a rich running TBI system. Could be your carb is rich and fumes are coming from the exhaust.
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Unread 09-13-2013, 06:39 PM   #12
sgtusmc_nc
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thanks windnot just confirming thats what you were saying.
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Unread 09-21-2013, 03:32 PM   #13
sgtusmc_nc
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Ok taking jeep to exhaust shop to fix tail pipe, next question is if you still smell exhaust with top up, and all Dorris and windows on? Should I start looking at the smog canister?
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Unread 09-21-2013, 04:33 PM   #14
walkerhoundvm
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If you're smelling exhaust with the top up, etc. I wouldn't be looking at the charcoal canister, I'd be looking for an exhaust leak.

If you're smelling fuel with the top up, etc. I would be looking at the charcoal canister plumbing (and gas tank, and fuel supply lines). There are about 1 brazillion threads on the forum about how to chase down fuel smells involving the canister.
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