I might have suddenly developed the dreaded evap cannister issue, but the symptoms aren't quite right, so I wanted to run it past you guys to see if you have any ideas.

I usually hit the gas station when the fuel gauge gets somewhere in the upper half of the red warning area, and I never top off. A few weeks back we were in a 100F+ (38C+) heatwave, so I put off filling the tank as long as possible. When the gauge was showing pretty much fumes left, I finally decided I couldn't wait any longer I stopped and gassed up. The pump cut off after about half a tank. I figured it was the heat and the twitchy automatic shutoffs we have here in California and left the station with half a tank. A couple days ago I'd run through that half tank and was just going into the red, so I stopped again, and the pump again delivered only half a tank before clicking off. This was a mild 75F (24C) day, but the same pump as usual. I decided to risk it and restart the fill, but it clicked off immediately.

When my XJ8 was having evap cannister issues, I had a different set of fill problems. At that time what was occurring was similar to what others describe in the threads (yes, I searched and read the threads ) where the pump clicked off immediately after a couple seconds until enough handle jiggling and slow fill speeds overcame the vapor issue and the tank filled normally.

So, I'm left with a few possibilities:

1. I compromised the evap cannister filling it on the really hot day;
2. The float in the fuel tank has sprung a leak and is reading half a tank too low;
3. The station updated the shutoff sensor on my favorite pump.

I can obviously address #3 in the short term by trying different stations/pumps (I almost always use the same pump. But #1 or #2 involve dropping the tank which isn't going to happen for a while.

Questions I have:

• Has anyone else had this "stop at half a tank" pattern from an evap cannister failure?
• Has anyone experienced/heard of a gas tank float failing in one of our cars? Is there a way to check without dropping the tank?
• Is there any potential worsening of the problem in accepting the halving of my driving range for now?

 

While I have no answer to your questions, I have to say that by continually running your tank down to “fume level” you are courting disaster. The fuel pumps in modern cars are cooled by the fuel around them. Repeatedly running the tanks to near zero is the most common cause of fuel pump failure. Don’t do it if it can be avoided.

 

What Greg said, and your problem probably is the evap canister is a goner. PITA though, you must drop the fuel tank to get to it. And to drop the tank...........
Yeesh.

 

OK, so "fume level" was a bit of hyperbole. And it is certainly not "continual" -- as I clearlysaid, I usually hit the station in the top third of the red bar so there's 2 gal or so still in the tank, but in the heat wave I made an exception and avoided fueling up for a bit longer than normal to not add gas fumes into the general air pollution miasma of the heat dome. At that time I was expecting to get 17 or so gallons in, but only got 8 in. Same thing when I stopped the second time -- I expected to get 15-16 gallons in, only got 7.5 in. That's why I was wondering if it there might be a cause other than the evap cannister, because on the XJ I was always able to eventually fill the tank, even if it was only in two second runs.

Thanks for the feedback guys.

 

still a PITA but on the 4.2, I think you have to drop the differential, not the fuel tank though. I would expect some codes if the canister was impacted.

@CurtJ did it throw any codes? If not, I suspect #3 - maybe only set the nozzle halfway. Some have done that with limited success. I had the issue once or twice some time ago and then went to a different station - problem never came back.

 

Hmm. Didn't think to check for codes (Last car I really worked on myself was a '67 Pontiac V8 over 40 some-odd years ago)

I found a P0232 for the fuel pump. No warning light, the pump doesn't seem to be running with the ignition off, and the battery doesn't seem to be losing charge. I tried to check the voltage on the pump with the key off, but couldn't figure out the Autel menu to get there.

I did check the cannister and EVAP tests with the engine running, they were a green and well within range.

 

hmmm… foaming up tripped the nozzle?? Happens all the time on the boat. Was the nozzle providing more than ample flow?

 

I have this problem as well. there are a few other threads about it. Odd thing is it will trip the pump and I'll have to dribble the fuel in every fill up for about 6 months to a year, then for some reason it will work fine for about 6 months. Crazy.

 

You have to drop the diff TO drop the fuel tank. The Evap Canister is above the tank.

 

OK I had to re-look at both the 4.2 and 5.0 manuals and neither indicated removal of the fuel tank is needed to access the canister. Both require dropping the diff eventual. I know I've read here on the forums the same comment you made, but I don't see it. Can anyone whose done it weigh in? The manual would not skip a step that significant. You know your stuff Cee Jay and I've not had to do it so I'll defer.

 

I shall peruse the Workshop Manual again... BRB

 

Well, huh. I guess the entire sequence is "Remove Diff (refer to instructions), Remove Canister".
My bad. I've looked at the IPBs of the stuff and it always appeared that the canister was above the tank.