On a 2000 GMC Jimmy, what causes the fuel gauge to fluctuate?

SOURCE: headlights and interior lights flicker

we had the same problem there is a small line that connects itno the alternator, it kept jiggling loose. we found a way to tighten it and the problem went away

SOURCE: fuel gauge stuck on half full

I can tell you almost for certain your fuel level sending unit is bad, I have been able to fix them though. It requires removing the gas tank and then the fuel pump. You can if your inclined, bend the brushes on the small circuit board over more so they will make better contact on to it. Other wise its a new fuel pump assembly, check all plugs and wiring by unpluging and repluging them to insure no bad connect. It is possible it could be the guage itself, but in thirty years of fixing cars never had a bad guage

SOURCE: where is my 1 2 shift sensor 2000 gmc jimmy

Inside trans. pan at the rear of the valve body. They have a wire clip which holds them in.

SOURCE: fuel filter, where is it located on a 2000 GMC Jimmy

fuel filter is located on the drivers side behind the rear quarter panel .
thanks and plse do not forget to accept the solution

SOURCE: 2000 GMC Jimmy won't start

i had the same problem and replaced the fuel pressure regulator. Cost about $45 at advance auto store or about $90 at napa auto stores. Once i replace that my truck started right yup and runs like a champ