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fuel smell

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fuel smell

New User | Posts: 20 | Joined: 03/08
Posted: 12/01/12
04:12 PM

I have a 1972 barracuda 318 2bbl recent new tank and sernding unit everytime i refuel i have a very strong odor of fuel and stays for a long period i have installed a new fuel cap and all lines to evap can are correct any ideas?  

waynep71222 waynep71222
User | Posts: 246 | Joined: 04/12
Posted: 12/01/12
09:22 PM

did your fuel sending unit or tank come with a new ORING to seal the sending unit to the tank... and a lock ring to hold the sending unit in place????

did the sending unit have a single outlet or  an outlet and return...

who installed the filler neck in the tank... some don't come with a filler neck.. so it needs to be silver soldered in...  with a big big soldering bludgen....

most early 70s fuel tanks have a carbon canister on the fuel tank vent line someplace..   usually with a line to someplace on the carb... or the air cleaner.. i can dig out my emissions manual for 72... so i can be sure ...

do you have any professional mechanic friends... or smog mechanic friends... one of them might have a fuel tank pressure tester kit..  some parts stores have them in the loan a tools..

it works like a radiator pressure tester... you pump a tiny amount of pressure into the tank with the fuel line pinched off at the front of the car.. and the hose going into the carbon canister... if the system leaks down.. this gives you the ability to find the leaks....

more than 2 pounds of air pressure may DAMAGE the tank... blow it out of shape...

this is the currently available locking gas cap... note its mostly plastic...

with a new one.. the plastic is still flexible... you can gently pry the bottom out.. get at the back of the lock cylinder and remove that.. use a tire stem with a fat bulb to blow some air thru the cap into the tank... to check for leaks..

so  a few answers...

i have also found the sending unit tubes loose in the plate.. so the fuel vapors and fuel could leak out..  on others the electrical components leak...  i have more than once when new ones were not available... drilled them out and replaced the rivets with a machine screw.. ..

please be careful.. fuel vapors are EXPLOSIVE....  they don't just burn..  fuel VAPORs EXPLODE...  

waynep71222 waynep71222
User | Posts: 246 | Joined: 04/12
Posted: 12/01/12
09:48 PM

in my motors emission control manual 3rd edition..

for 72 chrysler cars.. it shows 4 vent lines.. one from each corner of the tank... to a liquid vapor separator...   one of the lines is actually on a short tube inside the separator.. so any fuel that comes up.. will drain back into the tank...

the liquid separator actually has 5 lines on it.. on line.. goes to the carbon canister... some models have an overfill valve in the line to prevent flooding the carbon canister.....

from the carbon canister there are several lines..

one to the carb fuel bowl vent..

another to a TEE in the PCV hose...

another to from the purge control diaphragm fitting to the same line that supplies vacuum off idle to the distributer.. there is NO purge vapors coming in this line shared by the vacuum advance.. it only lifts the purge control valve diaphragm when the engine is above idle speed to allow the purge line into PCV hose operate... pulling vapors from the charcoal canister..

you don't want purge vapors at idle to be released into the motor...

i hope this explains the fuel vapor system

its called on chrysler built cars.. evaporative emission control system... ECS....

please let us know what you find...

it could be a single vent hose by the fuel tank top corners... could be the fuel separator unit..

there is a really good image on page 1-131  figure CL10  

New User | Posts: 20 | Joined: 03/08
Posted: 12/04/12
09:17 AM

Thanks very much, i now have a good working knowledge, i will consult my manual as well.  

New User | Posts: 20 | Joined: 03/08
Posted: 12/04/12
09:18 AM

Thanks alot very good info.  

waynep71222 waynep71222
User | Posts: 246 | Joined: 04/12
Posted: 12/04/12
10:49 AM

there are various shapes of fuel separators...





pepsi1 pepsi1
User | Posts: 150 | Joined: 10/11
Posted: 12/05/12
11:25 AM

Not being able to see into the Liquid/Vapor Seperator could one or more of those metal tubes be partially blocked or even plugged. If they are brazed or crimped, from the inside, even the slightest amount of braze or electric weld material could cause the raw fuel smell.
  Just my 2 cents. I have seen some weird and crazy things over my 40 years in the business. You just never know when you don't have the control of a part like that.