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bubble sound when Jeep turns off

poomero

poomero

NAXJA Forum User
Location
Tigard
1999 XJ 4.0 automatic

When I driving for any amount of time and the jeep is at operating temp when I turn it off I hear a gargling sound coming from what seems to be the gas tank. I am also noticing that I get shit MPG. Can I have a gas leak? Nothing is dripping out though. Can I have a leak at the injectors, gas cap, fuel rail? What can cause this if I dont smell gas and I dont have any viable leaks.
 
See if you gas cap has gone bad. Most systems are pressurized with about one psi. I believe of vacum. Attempting to hold gas vapors in the car. If if the cap does not vent at the right pressure things can boil

Think about it like your cooling system. Rasing the pressure raises the boiling point. I'm reverse it lowers the boiling point. That's why an AC system must have a vacuum drawn on it before charging, it boils out the water.
 
My 98 does this all the time, I don't worry about it, and it doesn't seem to be a problem.

Poor gas mileage would more likely be related to the condition of the tune-up parts, possible exhaust manifold leaks, or failed O2 sensors.
 
I will try the fuel cap. See where that leads. Tune up was just done with good parts so I dont think its that. I can change the o2 sensors and i dont think there are any exhaust leads
 
More than 75% of the XJ's I see in the junkyard have a cracked exhaust manifold. It would also be a good idea to confirm the Coolant Temperature Sensor is giving the correct readings by testing it.
 
Tim_MN said:
More than 75% of the XJ's I see in the junkyard have a cracked exhaust manifold. It would also be a good idea to confirm the Coolant Temperature Sensor is giving the correct readings by testing it.
Click to expand...

How do I rest this? Wouldnt I hear an exhaust leak?
 
Mine does this only when tank is full after a couple gallons are used it doesn't do the gurgling there was a recall on this back in the day I read somewhere.
 
poomero said:
How do I rest this? Wouldnt I hear an exhaust leak?
Click to expand...

maybe. My favorite test is to get it up to temp and dump seafoam through the brake booster vacuum line. White smoke will come out of any place with an exhaust leak.
If it doesn't smoke, have a friend shove a shop vac hose up the tail pipe and put it on blow while you feel around for air leaking from the header at the block all the way back. Do this when cold to avoid burning yourself.
 
dan1977p said:
maybe. My favorite test is to get it up to temp and dump seafoam through the brake booster vacuum line. White smoke will come out of any place with an exhaust leak.
If it doesn't smoke, have a friend shove a shop vac hose up the tail pipe and put it on blow while you feel around for air leaking from the header at the block all the way back. Do this when cold to avoid burning yourself.
Click to expand...

Both very good ideas. Thanks
 
Plenty of info on this known issue. The gurgling is coming from the tank vent. There's a
floating ball check valve there that closes the vent in case of a rollover. The noise is
harmless but enough owners complained about it and (years ago) the factory issued a
service bulletin for it. Basically, the dealer dropped the fuel tank and installed a lightweight spring against the float ball to prevent the gurgling noise. This spring is no longer available
from the dealer so we now have to live with the noise.
 
Poor MPG is most often something with the first O2 sensor systems having gone bad, bad fuse, bad relay, bad wires on the O2 heater circuit, or a bad O2 sensor.
 
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