Request for advice: Gas tank probs/Check Engine Light

[TBWCUMI]

Folks,

I drive a 2005 TJ that just recently went over 50K miles. I never had any problems with it until earlier this year when the 'check engine' light came on. The code was P2098: 1. Lean air/fuel ration- low fuel pressure 2. Vacuum leak on engine 3. Failed post HO2 Sensor etc...

I delayed getting it serviced because I noticed no real change in my driving or gas mileage and I wanted to save up some money first. The only thing that had recently been happening (and is still happening) is that when i fill up my gas tank, the pump does not cut off automatically when it is full and I dump some gas on the ground if I don't watch it towards the end of the fill.

So I finally made a service appointment today and they told me the reason for the C.E. light is that the PCM Software needed an update. Also, the dealership said that the overfilling of the gas tank was the fault of the excessive pressure of the pump (note that this happens everytime and everywhere I fill up) and short of replacing the gas tank (which only *might* fix the problem) there was nothing that can be done.

Can anyone validate that this is an accurate, or even common, assessment and fix of the potential problems resulting from a P2098 code? And most importantly, any advice on why my gas tank overfills each time? Thanks for the help.

 

[Bounty__Hunter]

I doubt that a trouble code was simply caused by the 'puter needing an update, but what do I know (I was wrong once before)

If the check engine light stays off and the engine runs fine, then no problem. Must've been it.

 

[jfrabat]

I dont know jack about this issue on the Jeep side, but the overpressure of the pump just does not sound logical to me...

The way the gas pump knows when the tank is full (the auto shut off) is that the gas pump has a small venturi in the tip, and while air is being drawn through the venture, the pump keeps on pumping. Once the fluid (in this case, the gas) level reaches the level of the venturi, the vacuum sucks in a little of the fluid, changing the vacuum pressure and activating the automatic stop.

This means that as long as the tank is filling up, the pump should shut off (reagrdless of shape, form, etc.). The only thing I can think of is that the pump is filling faster than what the shut off system can act, and thus you get the spill, but even so, it should shut off after the spill...

The cause could easily be that the auto shut off is broken (they tend to break easily because people use the tip of the pump gun to flip the switch of some pumps, or bang them into the neck of the tank). I used to work for Exxon (well, Esso in my case) and these things needed to be replaced often...

Anyway, I hope you figure out your problem! Hope this helps a bit!

Felipe