gauge is not readdin all the time.. floats, the goes to empty when empty,, read full most of time... whats cheapest way to fix????

 

Cheapest way is to reset the trip meter and fill up at 200-250miles.

Other than that, make sure all of the grounds are ok... More than likely, it is a faulty sending unit in the tank which requires the tank to be dropped for replacement. Not knowing what year you have makes it hard to recommend further. GM now has the sending unit sold separately from the fuel pump assembly on the newer '96+ trucks. I think you can get the sending unit separate for the older ones as well.

 

I just bought and installed a fuel pump in my 1997 for $97 from E-Bay.
I got mine from Global-Automotive.
This pump has a sensor installed so it fixes both problems at the same time, my gauge sender was bad also.
One tip, your hose connections to the tank are a snap on connector. After trying to get them off under the truck I finally just cut the nipples on the old fuel pump with a set of side cutters got the tank out of the way and then turned and compressed the connectors properly to remove them. Much easier, be sure to not cut the nipples flush with the end of the fitting so you have something to get a grip on.
If you are laying on your back doing this job send your loved ones away if you are prone to use profanity. Whatever you do replace the pump and sender at the same time you don't want to do this twice.

 

Hate to be captain obvious but the year is in the post title "99 4x4 blazer 4.3 fuel gauge". At any rate though swartkk is right that all ya probably need is just a new sending unit and you should be good to go.

 

Ha, would ya look at that!

Fixed your post though!! LMAO!