Losing the fuel smell

[Dino]

This may improve once I install the TQ but I'm a bit pessimistic.  The car runs great but after a 5 minute drive I smell like raw fuel and exhaust fumes and I'm getting tired of it.  My lungs have been tired of it for a while so I need to get this fixed.

The exhaust fumes were reduced once the header leak was fixed but it's still leaking somewhere, the collectors likely so I'll swap the gaskets for Percy's this spring.

So what is the solution for the fuel smell?  Is it the carb?  Will I never get rid of the smell unless I install efi? 

Do I need to cut out the variables and replace the entire fuel system? 

Please help DC-Com Kenobi, you're my only hope!

[six-tee-nine]

Vehicles with a carb will always smell after standing for a while. But in most cases (or my own expierience) the smell goes away when you drive it and the engine warms up.

If not there might be something wrong. However, you might need to determine if it is unburnt fuel (vaporised) or exhaust gasses your smelling. As you said, leaking exhaust manifols can give you a nice headache from the fumes (or from trying to fix them).


Oh and dont forget old cars need to have gassy smell

[WHITE AND RED 69]

How rich do you have the carb set? Are you leaking fuel? If you were going to swap the carb anyway I'd swap it to the new one and see if it helps any. Or lean out the current one just to see if it cuts down the smell? 

Have you thought about adding a return line to the tank? That might help.   

[Dino]

Ok I can see it smelling a bit after sitting, that makes sense.  However my car never sits for very long.  Even when I drive it all day, every day, it'll still make me dizzy.

So if the carb is rich, which it is, it's probably just throwing out the raw fuel with the exhaust fumes and if the exhaust leaks at the collector...then I'm basically sitting in an exhaust/fuel vapor mix...that ain't good.

I'm reading up on efi and saw the need for a return line, I guess it would be wise to install one regardless of fuel delivery system so I'll do that.  Do I need a new pump for that or can I use the stock pump?

I need to get busy on that TQ, I cleaned it all up but haven't done the actual rebuild yet.  Once it's on and the exhaust leaks are fixed it may solve the issue.  I hope...

Thanks guys.   

[super77se]

theres a number of reasons you could be smelling raw fuel

old plugs / ignition needing attention
stuck float / dumping fuel / flooding
rich mixture
fuel leak somewhere
missing grommets somewhere allowing fumes inside
door seals/trunk seals
tank vent / unvented gas cap
open element air filter
im sure ive missed something but , like said above, carbureted cars just stink sometimes

[Troy]

I always have my windows down - not because of that but it helps! Check the trunk and trunk seals. These cars seem to have some magic vacuum that will suck the exhaust right out of the pipes and into the car. Fixing the header should have made a decent improvement since it's in front of you. Gas smell is probably due to your current carb. Remember when it was at my garage and almost ran us out. My eyes were burning for 20 minutes! All of my cars seem to run rich at idle but not nearly that bad. When you swap carbs (assuming it's right) it should solve a lot of the raw fuel issues (and get you better mileage).

Troy

[Dino]

I always have my windows down - not because of that but it helps! Check the trunk and trunk seals. These cars seem to have some magic vacuum that will suck the exhaust right out of the pipes and into the car. Fixing the header should have made a decent improvement since it's in front of you. Gas smell is probably due to your current carb. Remember when it was at my garage and almost ran us out. My eyes were burning for 20 minutes! All of my cars seem to run rich at idle but not nearly that bad. When you swap carbs (assuming it's right) it should solve a lot of the raw fuel issues (and get you better mileage).

Troy

Oh yeah!  I had a headache for a day or two after that.   

I did manage to get it a little better but not a ton.  The header fix sur ehelped but I never tought about the trunk issue.

Windows down and keeping it moving sure helps but oh my when you step on it, it's like half of the fuel goes in the carb and the other half gets thrown in the cabin.   

theres a number of reasons you could be smelling raw fuel

old plugs / ignition needing attention
stuck float / dumping fuel / flooding
rich mixture
fuel leak somewhere
missing grommets somewhere allowing fumes inside
door seals/trunk seals
tank vent / unvented gas cap
open element air filter
im sure ive missed something but , like said above, carbureted cars just stink sometimes

I better check the firewall, I'm sure I've got this stuff wafting in somewhere.  Funny enough, even with the rich mixture the plugs are a nice tan/brown and dry.

[tan top]

 all whats been said  
also , in picture below  , check B  that the rubber pipe is not disconnected or split some how , also with A  i extended the pipe with suitable rubber hose it would  vent out side underneath the frame rail, not inside , bit of over kill may be , but i'm nutts like that  

[Brass]

I agree with Tan Top - check the filler neck vent tube.  Mine was venting into the trunk instead of exiting through into the frame rail.    There was also a missing body plug.  After fixing those two things (and with no exhaust leaks) the fumes are GONE - even though the car still seems rich at idle.

[SRT-440]

Some of it may just be the nature of the beast...My Grand National is fuel injected and smells of fuel bad and it's cuz there is no cat on the exhaust...if I replaced it most of it would go away.
Check again for exhaust leaks

[Just 6T9 CHGR]

Thats cologne to me....wife & kids say I stink bad after a ride in the car.....I beg to differ....  

[Cooter]

What's gonna suck Dino is, Even after you install this high dollar EFI system, and you still smell fuel.

It's a 1969 Charger..........Not sealed up as well as a 2012 Charger. No cats, No EVAP system, Etc. Course, this one isn't as cool...

[Back N Black]

I have a Holley 770 Carb. i don't get any fuel smell, well a little on start up.

[red69superbee]

my 69 coronet always made me smell like exhaust,seemed to get worse as time went on and seals got older.But old cars smell gassy and new ones will to if the catalytic converters arent there.I always had the tailpipes go out straight with tips, but changed to pipes that turn down under the bumper, and that took away about half the fumes i would smelll going down the road

[greenpigs]

theres a number of reasons you could be smelling raw fuel

old plugs / ignition needing attention
stuck float / dumping fuel / flooding
rich mixture
fuel leak somewhere
missing grommets somewhere allowing fumes inside
door seals/trunk seals
tank vent / unvented gas cap
open element air filter
im sure ive missed something but , like said above, carbureted cars just stink sometimes

I would try the above as most of it is free to do & not a bad idea just to make sure it is all working properly.

[XH29N0G]

Same as what the other guys wrote.

The smell always brings back memories of childhood.  For my car it can be intensified or lessened with jetting and carburetor adjustments, but has never completely gone away.  If it is different than before, than something must have changed.  Otherwise, it might just be the nature of the car.

[Dino]

Cologne eh?  

Thanks for all the comments guys.  I know it may be hard to get rid of all the smell but I'll go through everything listed here to reduce the issue as best as possible.  Now I had no idea about the cats...so what if I install cats?  Is that even possible on these things?  Will it ruin the wonderful music coming out the back?

I thought about losing the exhaust tips but I'm a bit hesitant, I like the stock tips a lot.  I'll try everything else before I do that but I may have to bite the bullet.

[bill440rt]

Thats cologne to me....wife & kids say I stink bad after a ride in the car.....I beg to differ....  

LOL
Me too! 
I try not to leave to door open too long from the garage into the house so the smell doesn't come inside. They HATE that. 

[tan top]

Thats cologne to me....wife & kids say I stink bad after a ride in the car.....I beg to differ....  

LOL
Me too! 
I try not to leave to door open too long from the garage into the house so the smell doesn't come inside. They HATE that. 

me three  although don't smell inside the car or even if windows open , but if idling away at a stop or in traffic etc & the wind is blowing a certain way , can smell it with windows down , 

been thinking what year is your thermoquad , only some not all have a esc vapour breather tube ! if not connected up , will have raw gas fumes worse then engine is hot ,

[Dino]

Thats cologne to me....wife & kids say I stink bad after a ride in the car.....I beg to differ....  

LOL
Me too! 
I try not to leave to door open too long from the garage into the house so the smell doesn't come inside. They HATE that. 

me three  although don't smell inside the car or even if windows open , but if idling away at a stop or in traffic etc & the wind is blowing a certain way , can smell it with windows down , 

been thinking what year is your thermoquad , only some not all have a esc vapour breather tube ! if not connected up , will have raw gas fumes worse then engine is hot ,

The TQ is a mid 70's but it's not on the car yet.  Currently has an Edelbrock 1407.  The TQ doesn't have that breather tube though.

[super77se]

The TQ is a mid 70's but it's not on the car yet.  Currently has an Edelbrock 1407.  The TQ doesn't have that breather tube though.

i knew i missed something lol , the bowl vent on a carb that isnt connected will allow fumes out as well.

i run a 1406 on my duster and after running it , then shutting it off when its hot outside, i get the infamous fuel percolation and can smell gas from outside the car ,but i never smell it on the inside. i also removed the charcoal canister and the tank vent line will seep fumes from time to time.

[Dino]

I used to have the boiling fus well, real bad.  Since installing the felpro gasket with crossover block that problem was taken care off.  Funny enough the smell is not so bad under the hood but it's bad standing next to the car and pretty much lethal standing behind it.

I will make sure that the firewall and its seals are fixed and the exhaust itself is leak free but would it be overkill to replace the  entire fuel system?  I don't seem to have any fuel leaks and the car runs fine but it is pretty old.  At the minimun I will replace the fuel lines but maybe I should just replace the tank and sender while I'm at it.

[super77se]

at the very least i would crawl under there and inspect the rubber line from the sender to the hard line. i would also check out the rubber from the tank line to the fuel pump. they get soft and mushy over the years. im not going to say you should replace the hard line unless you are pulling brown fuel from the tank. i had a super nasty tank full of rust. i only replaced the tank and to this day im using the hard line. definitely check all your body plugs while you are under there, there are a lot of them.

[Cooter]

Cologne eh?  

 Now I had no idea about the cats...so what if I install cats?  Is that even possible on these things?  Will it ruin the wonderful music coming out the back?

Catalytic Converters on CARB'd engines is a big no-no. Mainly because of the tune-up...Carb's dump fuel in the engine. ALOT of fuel= BAD for Cats.
Will burn 'em up within a few thousand miles. EFI? Only if the tune up is of a Stock type set up for fuel economy. A HUGE fuel curve will do the same thing even with that Electronic carb sitting on your intake. Afterall, the ZDDP you use in your "Oil burning" (by today's standards), 440 or whatever will KILL those cats.

[Blusmbl]

I think you're smelling fuel from the carb.  I've never had my Mopars do it, but my '66 Pontiac reeks of fuel after running it at WOT for 5-10 seconds.  The smell is definitely not coming from the exhaust, it's originating from the engine compartment.  Check what others have mentioned... float level, mixture, etc.

   

[Mike DC]

    
The air in the cabin (the air that is designed to be there) gets sucked in from the cowl inlet . . . which is right near the top of the engine.  That can't be helping anything.

 




I have sometimes wondered if it would help to try to seal off the cabin from the trunk area.  Not only for the exhaust/fuel smell but also just for general climate-control insulation help.

Block the big opening behind the rear seatback, and underneath the rear parcel shelf, and the openings into the roof structure under the C-pillars, and then inside the quarter panels above the outer wheelwells.  I would think it would help isolate the cabin area with all that stuff closed off.

[greenpigs]

Are you sure your getting a good spark at the spark plug?

[Dino]

at the very least i would crawl under there and inspect the rubber line from the sender to the hard line. i would also check out the rubber from the tank line to the fuel pump. they get soft and mushy over the years. im not going to say you should replace the hard line unless you are pulling brown fuel from the tank. i had a super nasty tank full of rust. i only replaced the tank and to this day im using the hard line. definitely check all your body plugs while you are under there, there are a lot of them.

I did take a quick look at the hard line when I was under there doing something...and as far as I remember it looked pretty good.  I'll definitely replace any rubber that's been in there 40+ years! 

I wonder if the tank venting shouldn't be redisgned anyway?  I get tired of having to be careful not to create a gas fountian at the pump and I'd like to find a way to fix that issue.

I think you're smelling fuel from the carb.  I've never had my Mopars do it, but my '66 Pontiac reeks of fuel after running it at WOT for 5-10 seconds.  The smell is definitely not coming from the exhaust, it's originating from the engine compartment.  Check what others have mentioned... float level, mixture, etc.

   

   
The air in the cabin (the air that is designed to be there) gets sucked in from the cowl inlet . . . which is right near the top of the engine.  That can't be helping anything.

 




I have sometimes wondered if it would help to try to seal off the cabin from the trunk area.  Not only for the exhaust/fuel smell but also just for general climate-control insulation help.

Block the big opening behind the rear seatback, and underneath the rear parcel shelf, and the openings into the roof structure under the C-pillars, and then inside the quarter panels above the outer wheelwells.  I would think it would help isolate the cabin area with all that stuff closed off.

Fuel coming from the carb and flying straight in huh?  Okay that's just plain dumb, how can we fix that?

You know I've been thinking about insulating the Charger as a modern car would be but I had not thought of blocking anything past the wheel wells, that's a damn good idea.  We have some sort of dense foam at work that we use to carve and shape body braces. (human body that is)  I wonder if I can shape it so it fits snug in the quarters.  It's too soft to ever move the quarter skin but it's dense enough that it'll block noise and fumes easily.  I'll have to read the msd on Monday and see if this stuff is flammable.

Are you sure your getting a good spark at the spark plug?

Seeing that it runs so nice and the plugs looked good my guess would be yes...but I'm not sure what else to look for.  What are the signs of a bad spark?

[greenpigs]

Wet plugs & a raw gas smell coming out the tailpipe are some.

Have you pulled a wire stuck a plug in and cranked it over in the dark? It should be a bright blue as you know.

It may run good but perhaps that 440 has even more than what you think. You should never smell raw gas at the tailpipes AFTER it has warmed up to operating temp IMO. If you got some nasty lumpy cam then you will have some unburnt gas but your ride is a mild build if I remember right.

[Mike DC]

              

You know I've been thinking about insulating the Charger as a modern car would be but I had not thought of blocking anything past the wheel wells, that's a damn good idea.  We have some sort of dense foam at work that we use to carve and shape body braces. (human body that is)  I wonder if I can shape it so it fits snug in the quarters.  It's too soft to ever move the quarter skin but it's dense enough that it'll block noise and fumes easily.  I'll have to read the msd on Monday and see if this stuff is flammable.

For this, I was picturing something like the big sheetmetal splash shields that fit behind the front wheels.  The big pieces that bolt onto the outer edges of the firewall and continue out to behind the fender skin.  Basically a sheetmetal piece, with a rubber edge maybe an inch wide to seal against the inside of the fender skin.  


I'm not sure what to do about underneath the C-pillars and the general area between the outer wheelhousings and the parcel shelf.  I wonder if moisture condensation would pose an issue if you foamed up the passages into the roof structure underneath the C-pillars.  

-------------------------------------


I got the whole idea from dirt track muscle cars I've seen built in decades past.  Sometimes they would put up a metal firewall at the backseat, and basically just not close up the trunk area at all.  They would fasten the fuel cell to the rear rails of the frame and there might not be any trunkfoor.   It would have made bodywork a helluva lot easier when the cars got crunched in back because the rear end could have been treated not much different from the front in that regard.  A hit on the quarters or rearend would have been less likely to distort the rest of the body and probably be more easily fixed. 


I was daydreaming about if the rear half of the car was built like the front - bolted-on quarters, with the trunk area unsealed past the firewall.  No worries about rusty trunkfloors, less worry about the whole car body getting screwed up from a collision anywhere behind the doors, etc.   

[Dino]

Would it help to install a vapor separator and return line?  My car left the factory with a 318 but now has a 440.  PO never changed the lines though so should I upgrade to R/T fuel lines?  The separators are on ebay for less than $50.