So I'm having issues with my fuel system again. Started noticing something was wrong when my fuel gauge will suddenly drop from full to empty then slowly make its way back up. Most of the time it sits on empty despite the amount of fuel in it. I could use some suggestions on where to start. I'm decently handy and I've done some work to my blazer already. Thanks!

 

Start with the easy stuff, sometimes a bad ground can cause a funky gauge. But it's probably the sending unit in the tank, I bet. What's in there right now? Factory, Delco/delphi replacement, or Chinese off-brand junk?

I've got the latter in mine, mated to an AC Delco pump. So far, the sending unit has held up for ~30k miles just fine.

 

like many people have said before these trucks are very picky with fuel pumps. with that said the gas gauge could be something as simple as the float stuck acouple good whacks at your tank could free it up or like stated above it can be a ground issue as well (also a common problem)

it sounds like you have a ground more then a stuck float so id look into that as a starting point

otherwise you can always just use your trip meter and reset it whenever you fill up...its a good fail safe when you have gas gauge issues i did that with mine and i think i filled up at every 200 miles or something like that

 

Cool thanks guys I'll check it out next time I get a chance. It's factory

 

I just replaced the fuel pump in my 02 Blazer a few weeks ago. First one had issues after getting it into the tank. (what an ordeal!). Had to replace it due to broken return line on pump and thankfully able to replace it without having to pay again!
Been working fine. I have noticed that if your sitting on a hill that the gauge will show that it is less gas than what's in there. Well rather slow in moving back to where it should actually be.
I wished replacing the other parts inside the fuel pump was a lot easier, than just buying a new whole pump.
Good luck with figuring out the problem.

 

just don't buy Airtex pumps... they are pieces of ****.

 

I totally disagreed with the above post. I have had a airtex pump in my 97 Jimmy for 7 yrs, still going strong. Not a single problem at all. Now they went back to lifetime warranty on their newer pumps, like the older days. I hate when people trash companys because they might have gotten a lemon. All Companys make lemons from time to time!

 

U kinda have a point however, with the 4.3 l they require lots of pressure and has been proven that in these trks none of the after markets pumps last very long!!!