Gas Tank Venting 68 F100

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Krussell
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Gas Tank Venting 68 F100

Post #1 by Krussell » Mon Dec 04, 2017 8:50 am

I think I've got a gas tank venting problem. I changed my carb out a couple of months ago along with my mechanical fuel pump because I think my tank wasn't venting and screwed it up. I bought what is supposed to be a vented gas cap from O'Reilly's and it clearly isn't because it sounds like I'm opening up a can of coke when I open it up. Sometimes it is dang near explosive. Anyway, my carb is running over now. I left the gas cap on just really loosely the other day and went to crank it up this morning. It is running over right from the start now. Question 1) Does anyone have a link to get an actual vented cap for this truck because I can't seem to find one anywhere? Question 2) Have I screwed up my mechanical fuel pump now again from this venting issue?

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bubba22349
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Location: Flagstaff, Az. 86005 near the old Route 66

Re: Gas Tank Venting 68 F100

Post #2 by bubba22349 » Fri Dec 08, 2017 6:46 am

:hmmm: It certainly sounds like the fuel tank isn't venting! Does your fuel cap look like this one (see below link)? It's Ford part # 8A 9030 this cap was used from 1951 to 1972 on F series pickups. There is a locking fuel cap made too Ford part # 01A-18416-A (see below second link). If you have a NAPA auto parts near you you might also try them. Most likely there wont be any damage to the new fuel pump and carb at this point, but that won't be known for sure until you can get the tank to vent. Good luck :nod:

Standard fuel cap
http://dennis-carpenter.com/fuel-tank-cap/p/8A-9030

Locking fuel cap
http://dennis-carpenter.com/fuel-tank-c ... A-18416-A/
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

Krussell
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Posts: 18
Joined: Sat Sep 30, 2017 11:47 am

Re: Gas Tank Venting 68 F100

Post #3 by Krussell » Tue Dec 26, 2017 4:30 pm

Sorry. I just saw this post. It does look like that. It must have lost its ability to vent. I got another one that seems to be doing ok, but my carb is still flooding.

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bubba22349
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Joined: Sun Jan 03, 2010 4:46 pm
Location: Flagstaff, Az. 86005 near the old Route 66

Re: Gas Tank Venting 68 F100

Post #4 by bubba22349 » Wed Dec 27, 2017 5:34 pm

Ok the next step then is to test your fuel pumps presure at the carb. Do you happen to have a combo vaccum / fuel pump tester (see below link). After you find out how pressure your fuel pump is putting out you may need to use a Fuel Pressure Regulator or you could also install a fuel return line to control excessive fuel pressure. Also do you know if the fuel tank is clean inside ie was this truck setting for a long time? If there is any crude inside it may cause damage to the fuel pump or carb. You could disconnect the fuel line from the tank at the fuel pump and use a lenght of rubber fuel line and a small gas can to test with. If some grit or crude got into the fuel pump it might be keeping the check valves from closing. Another alternative is to use a small electric fuel pump too. Good luck :thumbup: :nod: Edited


Combo Vaccum and Fuel Pump Tester.
https://www.northerntool.com/shop/tools ... gKYpPD_BwE
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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