I have a 99 jimmy that I am slowly replacing things on everyday wore out parts.Anyhow I was told my truck needed a fuel pump when I bought it off a guy in March.But what is confusing me it's still running but when like I start it and put it in gear it doesn't wanna go Nothing there even put it to the floor wont go and finally kicks in.Now the fuel gauge just keeps floating back and forth also.Now it does this all the time now and wonder if it's the pump for sure?And one other thing I got a read out that 2 o2 sensors are bad.The front and behind one on the converter.Now would those sensors cause a idle of it like loading up and then smelling some carbon or whatever to happen?So I have 2 questions here and hope I GWT a good answer..And could the fuel pump cause the rough type idle ?GOOD.DAY BRO"S

 

The fuel pump and fuel level sensor are a combined unit. Go to Rock Auto and search for the part and you'll find pictures or find a Youtube video on replacing these to see how it all goes together.

There are several threads on using a fuel line pressure test to diagnose fuel pump issues. Doing such a test will give you quite a bit of good info that can help with your diagnosis. The test is easy and the tool can often be rented for free from auto-parts stores.

As for the O2 sensors, they can go bad or the error can indicate that there is something wrong with the fuel delivery causing them to work poorly. On a 92 I used to have, I had a major oil leak from the injectors and this caused an over-rich mixture that created a lot of carbon build-up on an O2 sensor that gave me an error.

 

That was great info Christine..I just bought this truck from the 2nd owner of the truck and I do know it was well.kept and maintaince.It has 198,000 but all highway.I have been replacing wear and tear stuff one thing at a time..But this is my next thing to do is get the fuel pump replaced and those sensors..The truck is worth it I feel the body is solid no rust and is running good except the issues I gave you and the owner said it was gonna.need a fuel pump at the time but it hasnt gone yet so thought maybe its.getting worse cause the gas gauge is showing wrong reading more and bouncing around..Anymore input please let me know.
mark

 

Yes an O2S can cause poor idle. And foul the spark plugs from excess fuel. It must be replaced as a matter of maintenance not after it breaks. They generally are good for 80- 120K miles or until another fault deposits excess carbon on the sensor surface and damages the sensor.