Genright Fuel Tank Slow Fill

[XCRN]

My 2000 TJ with a Genright 25gal 05-06 tank has a slow fill issue where I can only depress the gas pump trigger halfway, so it won't shut off. With doing a 05-06 tank with different EVAP components as the vehicle it was going on and I also had no instructions on the proper way, I just made up what I was doing. I attached the fuel filler neck vent hose (small hose) straight to the small nipple on the tank. I have had this slow fill issues for years but just left it alone since it was more of an annoyance than an actual problem.

Fast forward to this weekend, I was installing a brand new from Genright 04 LJ Safari Tank that had the instructions, and I noticed on the instructions it had a different vent hose routing setup where it "Ts" off from the small nipple on the tank, the EVAP canister and the filler neck. Now I am wondering could I fix my slow fill issue on the TJ by installing a "T" fitting between the tank nipple, EVAP hose and filler neck vent port?

In the attached photos, the first one is of my actual setup and some lines I drew to represent my thought on routing. Second photo is straight from the Genright instructions on the 04 Safari tank and how the filler vent gets routed.

 

[gasiorv]

The tee would allow for it to vent to atmosphere and with gas cap installed would allow for vacuum to be pulled by evap system so it should work. If you want to test it to see if it helps your slow fill issue before splicing in the tee, disconnect your current vents from the evap line just before going to the gas station and see if it fills faster with the two small vents venting directly to atmosphere. Then after filling with fuel hook the line back up to prevent (or clear) the evap large leak code. If it fills faster then your idea should work, if it doesn't then there is another issue that needs resolved.

 

[XCRN]

The tee would allow for it to vent to atmosphere and with gas cap installed would allow for vacuum to be pulled by evap system so it should work. If you want to test it to see if it helps your slow fill issue before splicing in the tee, disconnect your current vents from the evap line just before going to the gas station and see if it fills faster with the two small vents venting directly to atmosphere. Then after filling with fuel hook the line back up to prevent (or clear) the evap large leak code. If it fills faster then your idea should work, if it doesn't then there is another issue that needs resolved.

I will have to try that. Fortunately the TJ is LS swapped so the EVAP is not exactly functional in the first place so I do not need to worry about a CEL issues. Currently the extent of the EVAP system is from tank to charcoal canister, and canister straight to throttle body. No valves in between, though I would like to make it somewhat function like factory eventually.

 

[The4bangertj]

Check the rubber hose that goes from the tank to the filler. Mine are pre bent and they’re still kinked a little bit. I don’t have any issues with mine but yours seem super straight so maybe it’s kinked thus only letting in a small amount of gas through.

 

[NashvilleTJ]

... Fortunately the TJ is LS swapped ...

Oxymoron?



I have an '04 LJ with the Genright '04 tank. If it helps at all, here is my hose setup which should be the stock configuration given I still run the EVAP stuff.

That said, I'm following closely as I too have the slow fill issue. Can't usually go faster than the first click, and it stops frequently. Certainly interested as to whether it is in fact driven by some kind of venting issue.

I had the tank out just a few weeks ago, and one thing I checked was that the roll-over valve functioned smoothly, and it appears to do so.

 

[oldjeepman]

I'll be watching also, I have the 31 gal tank in my 06. Have the slow fill myself.

 

[gasiorv]

I will have to try that. Fortunately the TJ is LS swapped so the EVAP is not exactly functional in the first place so I do not need to worry about a CEL issues. Currently the extent of the EVAP system is from tank to charcoal canister, and canister straight to throttle body. No valves in between, though I would like to make it somewhat function like factory eventually.

Is there a "vent" that would allow the air to escape somewhere between the canister and the throttle body? If not, I would say that would be your issue, there is not a proper vent.

I have a GR23 that is not hooked up to any evap system and I can't hold the fuel filler wide open most of the time. I think I can hold it on the 2nd click with no issue but if I try wide open it backs up, so possibly just the GR design to allow the extra capacity is also a factor.

 

[Wildman]

I have a 97-03 and have the slow fill issue also. I had thought it was the way I had the fill hose routed or something. Since mine isn't my DD it hasn't bothered me that much.
I have the GR23 like gasiorv.

 

[XCRN]

Oxymoron?



I have an '04 LJ with the Genright '04 tank. If it helps at all, here is my hose setup which should be the stock configuration given I still run the EVAP stuff.

View attachment 652984

That said, I'm following closely as I too have the slow fill issue. Can't usually go faster than the first click, and it stops frequently. Certainly interested as to whether it is in fact driven by some kind of venting issue.

I had the tank out just a few weeks ago, and one thing I checked was that the roll-over valve functioned smoothly, and it appears to do so.

Hey now, dont call me oxy!

Thats a little disheartening that even following the instructions still results in the slow fill on an 04. I haven't yet finished the install since the FPR decided to snap when I was handling it a little too aggressive so I have yet to fill this one at the pump.

On my 2000, I thought it was a matter of the fill hose size was much larger from the factory than the factory 05-06 fill neck and hose. It appears the one from my 04 LJ is the same as the 05-06 I installed on the 2000 when doing the GR tank.

 

[XCRN]

Is there a "vent" that would allow the air to escape somewhere between the canister and the throttle body? If not, I would say that would be your issue, there is not a proper vent.

I have a GR23 that is not hooked up to any evap system and I can't hold the fuel filler wide open most of the time. I think I can hold it on the 2nd click with no issue but if I try wide open it backs up, so possibly just the GR design to allow the extra capacity is also a factor.

I am not sure how the canister works but it is connected to the throttle body on the filter side of the throttle blade. So in theory it is open to the atmosphere depending on how the canister works.

 

[gasiorv]

I am not sure how the canister works but it is connected to the throttle body on the filter side of the throttle blade. So in theory it is open to the atmosphere depending on how the canister works.

I did some thinking (which is dangerous) and I don't think the "T" connecting the vent to the small tube going to the top of the fill tube is to allow air to escape but it is actually to allow fuel vapors from that fill line to escape out through the canister.

I think the canister has two outlets normally. One is vent to atmosphere and one goes to the purge valve. The third is an inlet from the tank. Normally the vent outlet is open so that the air can escape as the fuel tank is being filled, the fuel vapor gets trapped in the charcoal but the air escapes. The vent also stays open when the purge valve opens so that the intake can suck the fuel vapors out of the canister (if the vent does not remain open then the intake vacuum will create a vacuum in the canister). So make sure that vent on your canister is open and not plugged up, otherwise when you are filling the tank the air has nowhere to escape (on yours it should escape at the throttle body if there is no purge valve to stop it).

So, if you disconnect the vents going to the canister (as I said above) and it fills faster than you know you have an issue with the vent on the canister.

 

[XCRN]

Well filled up the 04 for the first time since getting the tank installed and it unfortunately also had the slow fill issue, just not as bad, like I can go full trigger for awhile but it will eventually shut off, but can hold 3/4 compared to half on the TJ. It also developed the “spit back” issue too.

 

[XCRN]

Ok to follow up, after the second fill up on the LJ after tank install, slow fill is fixed and it no longer spits back. So maybe the T fitting might help the TJ afterall. Wont be able to test soon since its also down for the winter for projects.