PatHenry

I had to use an O2 wrench to get my old sensor out. I found the crows foot style one more effective than the socket style. Since changing the sensor (I have only one on my 95) I've had to remove it twice while working on other things and since I was meticulous with the anti-seize I've just used a regular 7/8th wrench.

You can get the wrench set (which will have both styles) as a loaner tool from your local auto parts store - but they're inexpensive enough that buying one is just as good.

Hopefully since you're in the LA area the rust is not too bad and it will come out without too much trouble.

Janko

Thank you RocketMouse, I really appreciate it.
Unfortunately, I think my jeep may have a problem that I'm not going to be able to fix myself.
Originally, I thought that O2 was the cause of my poor mileage, but it seems that something is going on in the fuel tank. Yesterday, my gas gauge showed EMPTY, so I turned my jeep off and then back on again, and then it showed the correct amount of gas, which was 1/4. Inside my tank I hear some strange noise, is it the floater?? Fuel pump?? Something is obviously not measuring the amount of gas correctly, and sending the wrong info to the gas gauge. What do you guys think? Thank you in advance.

Janko

Thank you. PatHenry.
You're right: not too much rust on my jeep, even though I purchased it used in Utah about 11 years ago.
But, the O2 sensor may not be my problem now. Something weird is going on inside the tank. I posted it to RocketMouse.

PatHenry

Is the noise in your tank like a humming sound, or like a clanking/scraping sound?

You can normally hear the fuel pump prime as you're starting the Jeep. It's a mild humming type sound. The fuel pump and sender are integrated into the assembly inside the gas tank. I wouldn't think that a problem with the fuel pump or assembly would cause poor mileage - usually it's poor engine operation that indicates a bad pump. The sending unit and float mechanism can have issues and cause the erratic gauge behavior. However, If you turned the key off and back on and the gauge read correctly, I think you might have a wiring issue or gauge issue which I would check out first (since you have to drop the tank to get at the pump assembly.. also the assembly should be replaced as an assembly so it's a pretty pricey part on top of the difficulty in getting to it.).

Watch the gauges on startup and see if the fuel gauge reads empty again and note whether it had jumped up like the other gauges or if it was flat zero the whole time - the gauges should all spike up on startup before settling on a 98, if the gauge does spike and read zero, I'd suspect sending unit, if it's flat zero then gauge/wiring.

I'm not an expert though, so maybe someone has better advice.

BlueRidgeMark

Janko, you are probably seeing two separate problems. Maybe. Or maybe not.

By the way, before I get into that, the tip about heating the pipe to remove the O2 sensor is right on the money. They are almost impossible to get out otherwise. If you don't have a torch, you can just drive around until the beast is up to full temperature, then attack it quickly.

Now, to your (possible) two problems:

How are you measuring your fuel economy?

1. Are you recording the miles on the odometer and the fuel pumped in at the pump, as reported on the pump?
2. OR, are you going by the gauge and the miles driven?

The reason I'm asking is that fuel gauges are notoriously inaccurate. The only correct way to assess your fuel economy is the first method.

If you are using the second method, forget the O2 sensor (for now) and deal with the sending unit.

You might find there's no other problem.

FLXJ

I just replaced my upstream o2 due to poor fuel mileage and blowing black smoke and hesitating at temp. That Fixed all 3 problems, but gave me a new one. It won't rev past 3300 rpm when accelerating.

Waynerd

Another tip for removing the old 02. As long as it's not being reused you could break it off so a regular socket will fit on it. Apply a little heat. Then with an impact, give a quick pull of the trigger with it on tighten. Then proceed to remove. A lot of time that quick blast in forward will help break it free.