fuel problems? tank is full, gauge says empty
 

I have a 2001 silvy with 5.3. 155000 miles. changed fuel pump 3 yrs ago, and for the last 6 months its been getting harder to start. I changed the fuel filter and plugs and wires 4 weeks ago, hoping that would help. didnt do anything. whern i start the truck i have to turn it over, then let off the key, then try to start it again and then it fires right up. sounds like low fuel pressure to me.

just in the last 2-3 weeks i has been running rough, only sometimes. spits and sputters when i try to drive it, wont shift right..... I was going to get the fuel pressure checked but havent yet. had the codes ran, there was seven codes, all to do with knock sensors, low and high inputs on o2 sensors, the usual dumb shit.

then, yesterday i put 40 bucks in my truck and it already had a 1/4 tank in it. said full after i did that.

said full all day today till i got home, then it dropped down to completely empty and the low fuel light came on. turned the truck off and on several times and flicked the gauge, nothing.

I'm about to go check the ground on it, but anything else it could be besides the fuel pump? I think its the fuel pump, i mean with it running bad and then the gauge goin out....too much of a coincidence......

edit, checked the ground thats on the fuel filler and frame or whatever and its tight......no problems there i guess. is rough running and bad sending unit signs of a bad fuel pump? too expensive just to throw one in without that being the problem.

With all you said I'd say fuel pump IMO! Sometimes cluster go bad but they dont cause the truck to run bad!

I agree. anyone else?

Defently sounds like the fuel pump assembly, check the codes again and 99% chance you have a P0463 or P0462 stored for the fuel level sensor circut.

On our early 2000s trucks, the sending unit is riveted on and the rivet comes loose very easily after a few 1000 miles. This causes the "fingers" that send the signal to lift off of the circuit board. You can get the sending unit separately off of fee bay, but you might as well get an entire OEM assembly since you have so many miles and it may be failing too.

Also, clean out the gas tank. When I did my pump swap with about your mileage, there was brown sludge sh*t all over the bottom of the tank that will clog up your new fuel pump sock.

I don't know how ur going to change the fuel pump! But IMO pulling the bed is way easier!

just replaced this on mine. had to but the circuit board with the float arm attached, $235 dealer only item. that plastic sissy shit is very easy to break !

its most likely the fuel level sender. GM has an updated piece. just got mine. will be installing soon.

as stated in the op ive done it already, about 3 yrs ago, pulled the bed. this time i have a fiberglass cover and a welded rollpan....the whole bed has been repainted. not gonna take the chance on hurtin it. droppin the tank is not as bad as everyone makes it sound, plus you cant clean it out while its still in the truck.

so i'm just gonna buy a new pump if its all basically one piece, why not. better yet im gonna see if that pump i bought 3 yrs ago has a lifetime warranty.....