fuel gauge flucutation upon start up

ok guys I have 01 sliverado with 95K on it upon start up the fuel gauge bounces around? is this the fuel pump starting go south? or is it telling me i have a plugged fuel filter I do have a SES light on the truck seems to run fine though? The fuel gauge settles down after a while?

I will be getting the truck scanned tomorrow for codes...

i've got the same problem as u..at first the gauge either jumps around or marks wrong..after driving awhile it goes to the right level but if i come to an idle at a light for too long it jumps around again..i was told its the fuel pressure sending unit or somthing like that..i was told to unbolt the bed and switch out the fuel pump and sending unit sensor thing at the same time and its easier to take the bed off or raise it up then to drop the tank...i also have the SES light issue..mine is random..it will be on for a week and then stay off for a month..i dunno whats causing it..i've been told lots of things could cause it..bad gas cap..worn plugs...intake leak...i've yet to have the codes read..

the fuel pump sender unit is the cause ...this is a widespread GM defect as a result of a reaction to fuel additives...wait until the fuel pump fails then this fuel level indicator should work correctly...cost is too much to correct this just because the fuel level wanders occationally..


If the vehicle runs normally and you have a check engine light this is usually the fuel tank pressure/vacuum is not correct...

this is most common if you fill up the fuel tank to the max then park the vehicle....or park the vehicle in a heated garage...vapor lines get clogged with cannister charcoal...from liquid fuel contamination...

thanks for the response J cat - the codes point too the O2 sensors in the rear by the CAT which BTW have both been changed in the last 3 months. I was told its probably the Cat's? I assume this truck has 2 of them. Isn't the sending unit integral to the fuel pump? So I assume I have more than one issue here? Boy this truck is all of a sudden nickle and dime-ing me to death front end issues, front brakes now this stuff uhg.....

thanks for the response J cat - the codes point too the O2 sensors in the rear by the CAT which BTW have both been changed in the last 3 months. I was told its probably the Cat's? I assume this truck has 2 of them. Isn't the sending unit integral to the fuel pump? So I assume I have more than one issue here? Boy this truck is all of a sudden nickle and dime-ing me to death front end issues, front brakes now this stuff uhg.....

lets see what these codes are first ...then the forum will give you good advice on what is the problem..

the fuel pump is the fuel guage sending unit..my fuel guage has been doing this for 8yrs now...fuel pump still pumps ,,,I'm not worried about it..

kids auto shop teacher just gave him the good news but didnt give me the code #'s. So i will wait until they come back and get them scanned at Auto Zone is it common for the Cat's to go bad this early? Sent a kid to do a mans job... Also is there a differnce in o2 sensors ie GM vs NAPA vs Auto ZOne???

kids auto shop teacher just gave him the good news but didnt give me the code #'s. So i will wait until they come back and get them scanned at Auto Zone is it common for the Cat's to go bad this early? Sent a kid to do a mans job... Also is there a differnce in o2 sensors ie GM vs NAPA vs Auto ZOne???

It is imporant to get the correct codes on this failure as the parts are expensive....

the cat converters with normal operation and no gasket / fuel /ignition failures last about 200,000mi...then you will get a code related to the converter not properly controlling emissions ...


the correct O2 sensors will be the one that has the correct connectors...your vehicle all the O2 sensors should be the same,,,the upstream sensors are good for 100,ooomi at least..these vehicles have a very good monitoring system that reports quickly if these sensors are out of normal operation...

most time fuel delivery or a failed ignition causes the converters to get plugged and melted ...if this were the case you would not have very good performance..

My truck takes the Candian sensors for some reason. I am to the point of buying my scan tool this is a pain. The Truck runs fine performance wise nice power etc...

So until the SES light comes on Im flying blind I guess?

My truck takes the Candian sensors for some reason. I am to the point of buying my scan tool this is a pain. The Truck runs fine performance wise nice power etc...

So until the SES light comes on Im flying blind I guess?

those are the most common sensors used same as my vehicle all 4 are the same....

the PCM will surely tell you when somethings off ...if you are blind however you will not see the light ..

these code scanners are good to use ,,,very handy...do not buy an expensive one that falsely advertises it can read OEM enhance codes this is a scam ...unless this code reader costs over 1000.oo it can only pull generic codes ..therefore only spend 100.00 or so for the tool..

many of these companies are tricking techs into believing that they can read OEM specific codes,,but after you buy it your screwed.

Had the same problem for 5 years and not going to fix it till the pump goes out.