Please Stop Hissing At Me !
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Senior User
Joined: Oct 2002
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From: united states
Please Stop Hissing At Me !
Got another question guys and gals! On my 79 F100 5.0. When I pull the gas cap off of my truck I get a bad hissing noise alot of fumes come out too. This wouldnt bother me so much but when there is pressure in the tank the truck doesnt run like it normally does. It doesnt miss or anything like that but the drivability is different. Remove the cap for a second and everything is fine. I can only assume that the pressure in the tank affects the pressure in the fuel line to the carb. Warmer days only makes the pressure and problem worse. Should there be a vented cap on the truck? I cannot find a vented cap listed for it so i assume not. My truck has a stock pressure pump with one line in and out, I am running a holley 600 vac. secondary carb. Please help!
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From: clementsport canada
Please Stop Hissing At Me !
there should be a vent in the top of the tank, connected to the charcole canister on the front pass. side frame rail... this must be pluged..... but i dont' think you can get to it with out dropping the tank.
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From: united states
Please Stop Hissing At Me !
My truck doesnt have a charcoal cannister, or any emmisions equipment for that matter. It was all removed when i bought the truck. The vaccum line is still there that runs to the tank. Could i hook it up to a vaccum source? Would i have to get a cannister? Or would it be easier to get a vented cap, or make my cap vented?
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From: texarkana, tx
Please Stop Hissing At Me !
Joetee10 ---
Hi ya' dude. When I installed the 40 gallon tank on Harrison, I relocated the cannister from the engine compartment to back near the tank. It sounds like you say you have the connection to where it "should" be......
You could get the cannister from any number of candidates in the junk yard. The lead to the cannister is not under vaccum or pressure; it leads to a cannister full of charcoal which is suppossed to keep the foul odours of gasoline from reaching your nostrils... : )).
Hoping this helps,
Hi ya' dude. When I installed the 40 gallon tank on Harrison, I relocated the cannister from the engine compartment to back near the tank. It sounds like you say you have the connection to where it "should" be......
You could get the cannister from any number of candidates in the junk yard. The lead to the cannister is not under vaccum or pressure; it leads to a cannister full of charcoal which is suppossed to keep the foul odours of gasoline from reaching your nostrils... : )).
Hoping this helps,
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From: Albuquerque
Please Stop Hissing At Me !
[updated:LAST EDITED ON 11-Nov-02 AT 03:01 PM (EST)]
This is not a good situation. You could get gas blown all over you when you open the cap or even split the tank or a line.
You should have the vent line plugged somewhere near the engine compartment. It needs to be open to atmosphere, through a filter.
You could also try a vented gas cap but it may leak on turns.
This is not a good situation. You could get gas blown all over you when you open the cap or even split the tank or a line.
You should have the vent line plugged somewhere near the engine compartment. It needs to be open to atmosphere, through a filter.
You could also try a vented gas cap but it may leak on turns.
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From: united states
Please Stop Hissing At Me !
Thanks for the input! As for now i drilled a few holes in the cap to help with the pressure. So far i havent seen and fuel slosh out the cap. Seems to help my problem though. I am going to try and get one of those canisters this weekend though. Does the canister hook to the engine vaccum or does it just vent to the atmosphere?
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Please Stop Hissing At Me !
I've gone over this in some detail in the past. Check out this thread. The pictures don't load up anymore, but you can view them by searching kragen for the purge valve.
https://www.ford-trucks.com/dcforum/DCForumID91/11056.html
https://www.ford-trucks.com/dcforum/DCForumID91/11056.html
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From: Wolfforth
Please Stop Hissing At Me !
Mine is still missing that carbon granule cannister. We didn't discovered this while crawling around underneath it working on the tranny cooler lines and found another line that didn't go anywhere except to a hanging piece of hose. We put a screw in the end of the hose where dirt couldn't get in but air pressure could get out without blowing the screw out. The screw is still there and I don't have a hissing problem. My only problem is that I can't find a cannister etc, here in West Tx. If anyone knows where a good junk yard around here is, let me in on it!
Thanx!
Connie (only Ford luvr in the family!)
'79 f100 "Silver Ghost" (my baby)
'83 f100 "The Ford" (my first)
'85 f150 "Old Blue" (my next project)
Thanx!
Connie (only Ford luvr in the family!)
'79 f100 "Silver Ghost" (my baby)
'83 f100 "The Ford" (my first)
'85 f150 "Old Blue" (my next project)
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Please Stop Hissing At Me !
Almost any old Ford will have a charcoal cannister. The cannister absorbs the gas fumes into the carbon granules preventing them from escaping into the atmosphere to become the dreaded smog. A vacuum tube is used to draw the fumes back off the granules and into the engine for burning. Various valves are used by the OEM's to draw the fumes back in when they are needed.
To hook one up without all of the OEM valves you can plumb the tank vent in to the tank port. Run a vacuum line and tee it to the engine PCV inlet tube to the carb. Put a .032 dia orifice in the tube to restict the vacuum "leak". I use a 1/4" dia by 1" long piece of aluminum rod with a 1/32" hole drilled thru it. I frequently drill most of the way thru the rod with a 3/32" bit and just use the 1/32" bit for the last 1/4" or so. The orifice tube can be used with a short section of hose near the cannister so it is "identified" as part of that mechanism.
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To hook one up without all of the OEM valves you can plumb the tank vent in to the tank port. Run a vacuum line and tee it to the engine PCV inlet tube to the carb. Put a .032 dia orifice in the tube to restict the vacuum "leak". I use a 1/4" dia by 1" long piece of aluminum rod with a 1/32" hole drilled thru it. I frequently drill most of the way thru the rod with a 3/32" bit and just use the 1/32" bit for the last 1/4" or so. The orifice tube can be used with a short section of hose near the cannister so it is "identified" as part of that mechanism.
Thanks for using FTE!
[font color=red]As a Moderator I do not "Subscribe" to most topics,
please send email/pm if you need a reply -Thanks![/font]
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Please Stop Hissing At Me !
[updated:LAST EDITED ON 12-Nov-02 AT 11:25 PM (EST)]This isn't the best diagram, but it goes well with above posts. I'll take a gander at utilizing some of my member benefits. Here goes:
http://www.clubfte.com/users/tetraruby/CanisterGIF.gif
That's better...
http://www.clubfte.com/users/tetraruby/CanisterGIF.gif
That's better...
Posting Guru
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From: Gainesville, FL
Please Stop Hissing At Me !
Joe,
Your problem is not the carbon canister! Your problem is the tank is not vented. Let your tank vent to the atomsphere. If the vent line is clogged, clear it! Yeah, it's against the law but, I think you could take the risk. Just never tell anyone. If the police pull you over, just act normal! If they want to look under the hood, try and act drunk to distract them. It a crazy world we live in; just try and make it another day.
My Way is the Highway,
KingFisher
Your problem is not the carbon canister! Your problem is the tank is not vented. Let your tank vent to the atomsphere. If the vent line is clogged, clear it! Yeah, it's against the law but, I think you could take the risk. Just never tell anyone. If the police pull you over, just act normal! If they want to look under the hood, try and act drunk to distract them. It a crazy world we live in; just try and make it another day.
My Way is the Highway,
KingFisher
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From: texarkana, tx
Please Stop Hissing At Me !
dfisher1 ---
I don't know about that, man...here in Georgia we have vacuum hose police....they'll scope out your rig front to rear looking for hoses that are not proper..
I don't know about that, man...here in Georgia we have vacuum hose police....they'll scope out your rig front to rear looking for hoses that are not proper..