98 Bravada Fuel Pump

My 98 Bravada fuel pump quit, so I pulled the tank and went to the junkyard and bought a $75 used pump. Successfully replaced the pump. but now the fuel gauge is reading erractically. It will register full (when tank is full) but seems to stick at 3/4 full. I was told by dealer that according to VIN#, I have an 18 gallon tank. I am wondering if I have installed an incorrect fuel pump. It "looked" exactly the same, but I know that the GM part number on the top of the pump wasn't the same. Just wondering if a fuel pump from a Blazer or Bravada with a smaller fuel tank would react this way if installed into an 18 gallon tank. I expect that the answer is to pull my tank again, and then just switch out the bad motor with the good motor and reinstall my original fuel pump assembly. This is what I was going to do, but it was back in February and it was 20F here in Michiagn, and I needed to get the trusty old Bravada back on the road. Thanks in advance for any help.

Did you change the fuel level sensor(float) too? On the fuel level sensor, the "wipers" on the potentiometer break off and loses contact with the rest of the pot, possibly giving you a false signal because the fuel level buffer remembers the last info and won't update it. When I recently changed mine, it was to primarily restore the fuel level sensor & obtain correct guage readings and since it had run out of fuel on several occasions, it was just a matter of time until the fuel pump would quit...most likely while on vacation this summer. The excessive fuel prices are going to keep me home right now. There's plenty of things to check out in my home town and I can save on motel bills too. Check your home areas for places to see and save yer gas this year.

The fuel pump on my 2000 (about 50k) is whining pretty bad, and the level gauge is useless - can you give me some pointers on this repair?

Ball joints, hubs, and MacPherson struts are easy, but I've never done serious fuel system work...

Thanks

I helped a dealer mechanic friend do mine.
First I ran out as much fuel as I dared then we jacked the car up and set all 4 corners on jackstands on a concrete floor and disconnected the battery posts. Gotta be safe. Remove the spare tire so you can work at the rear of the tank.
After disconnecting the fuel filler line and vent line, we took the tank straps loose and dropped the front of the tank low enought to take the wiring connectors loose from the tank. We used some disconnect tools to get the pushloc fuel connectors loose from the fuel connections. We moved the tank down and toward the front of the car to get it down. There are plastic protection covers on the tank that seem a little difficult but it's better to maneuver and work the tank with them in place. After taking the tank out from under the car, we completely drained the tank of gasoline out the fill line connection so it would be lighter going back.
We cleaned the snap ring and pump area with solvent, brush and lots of air...you don't want ANY junk to fall in the tank while taking out the pump assembly. Remove the snap ring, blow any more debris with air and gently pull the fuel pump assembly out after marking the position of the old pump & o-ring.
Clean and grease the o-ring and set it in the opening, set the new pump/level sensor assembly and push it down gently and evenly until it seats in the opening then install your snap ring. Scoot the tank back under the car. With the plastic protectors and holding straps in place, raise the rear of the tank and place it rearward in position while gradually raising the front of the tank then start a bolt in the front strap. We then connected the fuel filler & vent lines, the fuel supply & return lines and wiring connectors. With everything in place and connected, we bolted the rear strap in then tightened the front strap. Satisfied we were ready for a leak test, We put in the fuel then connected the battery and turned the key on to start the pump. Finding no leaks, we re-installed the spare tire and let the car off the jackstands and went for a test ride with a working fuel level guage.
If I left anything out, I'd be mighty grateful for any help ya'll.

im new to the forum, but id like to ask a question, i have a 98 bravada and i had the fuel pump replaced because it broke, by the way, dont let your gas get below a quarter tank because your pump is exposed and over heats and when u get gas the rapid cooling will break the pump, just a tip, but anyway my mechanic got me the napa fuel pump with the life time warranty, and 2 weeks later the check valve went bad on the pump, car took forever to turn over, so i got a new pump again it was fine for a week and tonight it started going bad again..meaning it took forever to turn over, anyone know anything i dont about this? or have any suggestions?..starter checks out, spark plugs are new, alternators new, distrubutor cap seems to be ok, ignition wiring is new, fuel pump just keeps randomly going out...are the napa ones junk or....hell i dont know help me out!

You might have the fuel pressure checked to see if that's the problem...I think it's supposed to be around 60psi.

one reason for excessive crank time before starting could be the crankshaft postion sensor. I had this replaced on one of my vans with the 4.3 engine and it took care of the problem.

another problem may be water in the gas tank. drain it and if you live in a high humidty area use the STP water removal additive at least once a year. it's actualy just a blend of alcohols that binds with the water and removes it by moving it thru the combustion process.

Isn't it disgusting that you have to drop the tank to change a fuel pump on GM products, particulary because they seem to have been failing at an excessive rate for over 20 years. My Dad's Chysler had an access hatch in the trunk.

thanks everyone for you suggestions, i stopped by my mechanics garage and we figured out once again the check valve went bad and i was losing pressure as soon as i shut off the car, problem will be taken care of tuesday! anyone had problems with the hatch release? ( the one the key goes into on the back) or the rear wiper stopping mid-wipe?