Fuel Tank Vent return lines

Modified FSJ Tech Area
Post Reply

Topic author
ShagWagon
Posts: 702
Joined: Tue Apr 19, 2016 8:13 pm

Fuel Tank Vent return lines

Post by ShagWagon »

Will this work?
Image
Vacuum can diaphragm was shot and I do t have a carb anymore so I removed charcoal can and did this through blue can and back into intake.
Last edited by ShagWagon on Thu Jul 20, 2017 11:09 am, edited 1 time in total.
87 Grand Wagoneer Rebuilt 360 by S&J, Fitech GO EFI 600, Novak in-tank fuel pump, Skyjacker Hydro 4" lift, BFG AT KO2 30", Dynamax Muffler, MSD distributor, MSD ignition, Edlebrock perf 4bbl intake, Elgin perf cam, Oil tube mod, Roller rockers, chrome molly lifters, HD alum radiator, Powermaster 150/100 alt, Alum HD water pump, Serhills tailgate harness, Cowl screen mod, Evil Twin grab handles, Rstep's custom AMC door lock knobs, all electrical works.
User avatar

kansasboy001
Posts: 234
Joined: Tue Jan 31, 2017 1:47 pm

Re: Fuel Tank Vent return lines

Post by kansasboy001 »

Umm not really. You'll be applying full manifold vac to the gas tank which is not a good thing. You'll endup getting raw fuel in there. Just get a new canister from a early xj, yj, or zj. Your local salvage yard is bound to have one. And even better the newer canister has one input blocked which will work for your efi.
1983 Cherokee Laredo. 360/ 727/ np228/ Junkyard 7427 TBI/ Msd ignition

Topic author
ShagWagon
Posts: 702
Joined: Tue Apr 19, 2016 8:13 pm

Re: Fuel Tank Vent return lines

Post by ShagWagon »

Thanks.

My idea was that the gas fumes would get sucked back in and recycle with the blue catch can(?) catching any buildup of liquid fuel. I didn't want it just dangling in a J bend at the end.

I'll keep an eye out for a charcoal can. Have to ask what's the propose though. Does it just act as a big sponge? The charcoal can has a vacuum to it...

Would it be better to put into the throttle body vacuum port instead?
87 Grand Wagoneer Rebuilt 360 by S&J, Fitech GO EFI 600, Novak in-tank fuel pump, Skyjacker Hydro 4" lift, BFG AT KO2 30", Dynamax Muffler, MSD distributor, MSD ignition, Edlebrock perf 4bbl intake, Elgin perf cam, Oil tube mod, Roller rockers, chrome molly lifters, HD alum radiator, Powermaster 150/100 alt, Alum HD water pump, Serhills tailgate harness, Cowl screen mod, Evil Twin grab handles, Rstep's custom AMC door lock knobs, all electrical works.

Topic author
ShagWagon
Posts: 702
Joined: Tue Apr 19, 2016 8:13 pm

Re: Fuel Tank Vent return lines

Post by ShagWagon »

Can I use a vented gas cap and plug these vent lines completely?

Then is no need for blue can or charcoal canister at all?

What if I dropped an intank hi pressure up to 100psi fuel pump in the tank?

Thanks
87 Grand Wagoneer Rebuilt 360 by S&J, Fitech GO EFI 600, Novak in-tank fuel pump, Skyjacker Hydro 4" lift, BFG AT KO2 30", Dynamax Muffler, MSD distributor, MSD ignition, Edlebrock perf 4bbl intake, Elgin perf cam, Oil tube mod, Roller rockers, chrome molly lifters, HD alum radiator, Powermaster 150/100 alt, Alum HD water pump, Serhills tailgate harness, Cowl screen mod, Evil Twin grab handles, Rstep's custom AMC door lock knobs, all electrical works.

weeegoneeer
Posts: 230
Joined: Wed Apr 26, 2017 10:34 am

Re: Fuel Tank Vent return lines

Post by weeegoneeer »

Mine just vent to the atmosphere under my hood, just open hoses hanging out. Never smell gas and do about 20,000 miles a year so hoping it's ok?
1984 GW
User avatar

tgreese
Posts: 7119
Joined: Fri Jun 08, 2012 6:31 am
Location: Medford MA USA

Re: Fuel Tank Vent return lines

Post by tgreese »

ShagWagon wrote:Can I use a vented gas cap and plug these vent lines completely?

Then is no need for blue can or charcoal canister at all?

What if I dropped an intank hi pressure up to 100psi fuel pump in the tank?

Thanks
Yes, you can use a vented cap and plug the vapor recovery lines. Then you use no charcoal canister. This is how cars were plumbed before we started worrying about emissions. Realize that your garage will smell like gas, and often you will smell gasoline around the Jeep. Again, this was normal around mid-century.

If you install an in-tank pump for EFI (for example), it will need a return line. This is separate from the pressure inside the tank - the in-tank pump has no effect on that. Regardless, you must vent the interior of the tank, wheterh direct to the air with a vented cap, or through the charcoal bed of a vapor canister.

Just a comment - removing the vapor recovery system on these cars is terribly wrong-headed. Vapor recovery works well, has zero performance impact, requires almost no maintenance. And the system is very beneficial, venting your tank, recovering evaporation losses, preventing gasoline smell, and benefiting air quality. My advice - keep it, fix it.

An additional comment - the vapor recovery system should also slow the deterioration of the ethanol/methanol enriched gas in your tank. Modern gas goes bad quickly in a gas can; I expect it does the same in a vented tank.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.
Post Reply