kingoftooland
Active Member
ok so I just have had enough of this problem n I gotta solve this FAST I got a edlebrock 500 cfm carm and no matter whet I do it reaks of fuel after I turn it off what in the world is going on
O.o gas fumes
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Oldiron440
Well-Known Member
The Edelbrock carbs and today's fuels have a problem of boiling the fuel bowls dry after the engine is shut of. What your smelling is the vapor from that. It might help to put a ploy spacer between the carb and intake manifold but I have my doubts.
i second, oldiron440. If you had fuel puddles, I’d have a couple other guesses but, strong odor after parking is likely fuel boiling in the bowls.
I went with the 1901 625cfm Demon carb with composite bowl particularly to avoid this issue. Has worked as advertised so far.
I went with the 1901 625cfm Demon carb with composite bowl particularly to avoid this issue. Has worked as advertised so far.
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XfbodyX
Well-Known Member
Id ask if you have to crank it alot when you refire it? You could be boiling it but you could also be dripping or dumping raw fuel into the intake. How is the carb vented? I have noticed todays gas also has a strong smell weather in a car, or sitting in a gas can in my shop, alot evaps off. As odd as it may sound 35 years ago gas had a good smell vs todays gas thats very oppressive.
kingoftooland
Active Member
Well not really I pump the gas 3 times n she lights right off and I got not even a 6 month old edelbrock performer 1403 carb I have not jetted it or anything just made a simple idle adjustment otherwise it’s just as it was right out of the box
XfbodyX
Well-Known Member
Any chance your just used to newer cars that never smell? You didnt state how you had the carb bowl vented if it has one?
kingoftooland
Active Member
I’ll have to look into it but I believe it has a vent it runs right into the air filter just lately now that I have but the proper temperature thermostat in there the smell is worse because last night I had it in the garage and now I have neighbors complaining about smelling gasoline in their house
Aspen500
Well-Known Member
If the carb is vented to atmosphere, you will smell fuel yo a certain extent after shut down. That was a normal thing until the early '70's when vapor recovery systems were added. It's just like how a non-catalyst vehicle smells like it's running rich when actually, all cars smelled that way prior to 1975 or in the '70's having to start the car 5 times before you get out of the garage on a cold engine. It was normal but we forget how it was in the past.
Not sure how your neighbors could smell gasoline fumes coming from your garage though without having it dripping on the floor or something.
Not sure how your neighbors could smell gasoline fumes coming from your garage though without having it dripping on the floor or something.
XfbodyX
Well-Known Member
After you shut it off, look down the carb to see for gas running into the intake or if you can hear it boiling off. As well look down to your fuel pump all the way up, you may have a leak.
AJ/FormS
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What size cam are you running and has this been ongoing with that cam?
Are you still running the Charcoal cannister?
Is there a return line to the tank?
Are you still running the Charcoal cannister?
Is there a return line to the tank?
kingoftooland
Active Member
Nope this is the setup
a edelbrock 1403 carb and performer intake
AJ/FormS
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I can see your problem from here.
It's that open air filter housing.
Any fumes happening at shut down, escape straight to atmosphere, and since they are lighter than air, will sit right up under the hood, trying to escape where ever they can, like between the hood and the fenders and up into the cowl past a poorly sealing cowl-seal.
But , you say, those fumes shoudn't be escaping should they?
Well why do you think Ma Mopar designed; the charcoal canister, the sealed air cleaner housing, and the automatic bowl-vent closing system? With all those vacuum lines.
Yur not doing your engine any favors feeding it hot underhood air; it tends to cook the gas, and limits power production.
Imagine your engine being force-fed the hot air coming from the rad blasted at it by the factory A/C fan. When you shut it off, the carb could already be at 200*F or more degrees.... and the lightest aromatics in the gas evaporate at 95*F, most at less than 200*F, the syrup takes a bit more, close to 400* I seem to remember.
And if the that intake has an EGR on it or even just a functional crossover passage underneath the carb, there is hot exhaust in there up to, in the range of 800 to 1000 degrees,cooking the carb right there. Criminy the exhaust can be 350/400 just at idle.
But that air cleaner "housing" sure looks pretty.
It's that open air filter housing.
Any fumes happening at shut down, escape straight to atmosphere, and since they are lighter than air, will sit right up under the hood, trying to escape where ever they can, like between the hood and the fenders and up into the cowl past a poorly sealing cowl-seal.
But , you say, those fumes shoudn't be escaping should they?
Well why do you think Ma Mopar designed; the charcoal canister, the sealed air cleaner housing, and the automatic bowl-vent closing system? With all those vacuum lines.
Yur not doing your engine any favors feeding it hot underhood air; it tends to cook the gas, and limits power production.
Imagine your engine being force-fed the hot air coming from the rad blasted at it by the factory A/C fan. When you shut it off, the carb could already be at 200*F or more degrees.... and the lightest aromatics in the gas evaporate at 95*F, most at less than 200*F, the syrup takes a bit more, close to 400* I seem to remember.
And if the that intake has an EGR on it or even just a functional crossover passage underneath the carb, there is hot exhaust in there up to, in the range of 800 to 1000 degrees,cooking the carb right there. Criminy the exhaust can be 350/400 just at idle.
But that air cleaner "housing" sure looks pretty.
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Kernel Sanders
Well-Known Member
I run an open air filter and dont get a strong gas smell (there is a little because my Eddy carb does not have the provision for venting to my charcoal canister).
I'm in agreement that its either a leak, possibly a high float, or fuel boiling.
Can try a higher premium gas (I dont use E85 garbage in carbureted engines) and a phenolic spacer to help prevent so much heat soak to the carb.
I'm in agreement that its either a leak, possibly a high float, or fuel boiling.
Can try a higher premium gas (I dont use E85 garbage in carbureted engines) and a phenolic spacer to help prevent so much heat soak to the carb.
I’m not convinced that it is all fuel from carburetor bowls. Could be the only source but I suspect there might be something else (maybe).
There are three metal lines coming from the fuel tank: 5/16”, 1/4” and 3/16”.
The 5/16” line goes to the fuel pump from frame rail.
The 1/4” line goes from fuel filter back to frame rail (excess fuel return to tank)
The 3/16” line goes more forward and to the charcoal canister (fuel tank vapor feed).
All three metal lines have a rubber hose connection underneath car close to the firewall (as shown below).
From there, all three lines go to the fuel tank.
That is nine possible leaks from the rubber hose sections. Before the engine, there are six different metal fuel lines that might have suffered physical damage and/or rust through.
This is from a '84 Gran Fury 318. The second picture shows the hoses by the firewall under car. I saved these so I could make duplicate lines for my cars, out of stainless (just another project I've yet to tackle).
The fuel filler neck grommet (to tank) is another common leak. Dodge part number 4002010 – which is still available. The MSRP is $18.10 (US) though (as of today).
This how crackled the grommet is on my wagon. I’ve seen a couple at the pull-a-part that are “almost gone”.
What I would do is take some clean pieces of cardboard and place underneath car on the passenger side of car from fuel tank to fuel pump, after a turn off. Avoid getting cardboard close the catalytic converter, though. The fuel will evaporate but will leave a stain on the clean cardboard. If nothing, then see if you can do the same on an incline engine pointing up one night and down the next. If you have a non-carburetor/fuel pump leak it will show up in one of the three methods indicated. If you can get under car – there should not be any cracking of either of the nine (frame) sections of fuel hose.
Also, the Charcoal canister has three (of four) hoses going to it. The 3/16” hose from tank, a large and small hose from carburetor (which one or both might be disconnected) with the different carburetor installed.
The big carburetor hose comes from carburetor top and is used to capture fuel vapors that come from it (mostly at engine turnoff). If this one is not used (might not have a provision on existing carburetor) you will need to cap this off at the charcoal canister. The small vacuum hose pulls a small vacuum to the charcoal canister which sucks those fuel vapors down to be burned off. Some systems use manifold vacuum (base of carburetor) and some use venturi vacuum. Some use a fourth hose as a turn on/off valve (for 4-port charcoal canisters).
This is an A-body TQ. The blue circle shows the large hose for vapor collection.
Another possibility might be if the charcoal canister is not getting any vacuum it might be saturated with fuel vapors – for charcoal can only hold so much.
In my opinion, the charcoal system is not worth the effort removing (more beneficial than not) – but it can be removed from car (in non-emission states, only). If you do remove it, it might be best for find an older car (Mopar or not) fuel tank vent system and place in rear of car. Fuel vapors running loose in the engine compartment doesn’t end well, in the long run.
BudW
There are three metal lines coming from the fuel tank: 5/16”, 1/4” and 3/16”.
The 5/16” line goes to the fuel pump from frame rail.
The 1/4” line goes from fuel filter back to frame rail (excess fuel return to tank)
The 3/16” line goes more forward and to the charcoal canister (fuel tank vapor feed).
All three metal lines have a rubber hose connection underneath car close to the firewall (as shown below).
From there, all three lines go to the fuel tank.
That is nine possible leaks from the rubber hose sections. Before the engine, there are six different metal fuel lines that might have suffered physical damage and/or rust through.
This is from a '84 Gran Fury 318. The second picture shows the hoses by the firewall under car. I saved these so I could make duplicate lines for my cars, out of stainless (just another project I've yet to tackle).
The fuel filler neck grommet (to tank) is another common leak. Dodge part number 4002010 – which is still available. The MSRP is $18.10 (US) though (as of today).
This how crackled the grommet is on my wagon. I’ve seen a couple at the pull-a-part that are “almost gone”.
What I would do is take some clean pieces of cardboard and place underneath car on the passenger side of car from fuel tank to fuel pump, after a turn off. Avoid getting cardboard close the catalytic converter, though. The fuel will evaporate but will leave a stain on the clean cardboard. If nothing, then see if you can do the same on an incline engine pointing up one night and down the next. If you have a non-carburetor/fuel pump leak it will show up in one of the three methods indicated. If you can get under car – there should not be any cracking of either of the nine (frame) sections of fuel hose.
Also, the Charcoal canister has three (of four) hoses going to it. The 3/16” hose from tank, a large and small hose from carburetor (which one or both might be disconnected) with the different carburetor installed.
The big carburetor hose comes from carburetor top and is used to capture fuel vapors that come from it (mostly at engine turnoff). If this one is not used (might not have a provision on existing carburetor) you will need to cap this off at the charcoal canister. The small vacuum hose pulls a small vacuum to the charcoal canister which sucks those fuel vapors down to be burned off. Some systems use manifold vacuum (base of carburetor) and some use venturi vacuum. Some use a fourth hose as a turn on/off valve (for 4-port charcoal canisters).
This is an A-body TQ. The blue circle shows the large hose for vapor collection.
Another possibility might be if the charcoal canister is not getting any vacuum it might be saturated with fuel vapors – for charcoal can only hold so much.
In my opinion, the charcoal system is not worth the effort removing (more beneficial than not) – but it can be removed from car (in non-emission states, only). If you do remove it, it might be best for find an older car (Mopar or not) fuel tank vent system and place in rear of car. Fuel vapors running loose in the engine compartment doesn’t end well, in the long run.
BudW
kingoftooland
Active Member
You know I did not think it had 3 lines I know I had a leak at one time on the line that is going from the right frame rail for the fuel pump feed it rotted out under the little steel cover behind the upper control arm on the passenger side n yes I have the char coke canister removed and the line capped off now could it be a excess buildup of fuel vapors in the tank??
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Aspen500
Well-Known Member
You need a fuel tank vent. Ideally it would vent to the charcoal canister but it has to be vented. If the vent line from the tank is plugged off, you can get pressure build up in the tank when the fuel temp rises. It could cause vapor to exit the system at the weakest point (could be filler neck grommet, fuel sender gasket, cap, etc) On the other side, it can also make a vacuum in the tank as the fuel is used. At some point, the cap will vent pressure or vacuum.
Doubt it would happen on older cars but I have seen tanks gets collapsed when the vent system is plugged for one reason or another. Sucks the tank in like the old science class experiment with the one gallon paint thinner can, add some hot water and then screw the cap on and wait for the water to cool.
Doubt it would happen on older cars but I have seen tanks gets collapsed when the vent system is plugged for one reason or another. Sucks the tank in like the old science class experiment with the one gallon paint thinner can, add some hot water and then screw the cap on and wait for the water to cool.
