Does anyone specifically know how to replace the sending unit using the TRAP DOOR method? Is it just "plug-n-play", or do I have to disconnect lines and all that?

I have a 1999 SS Camaro and the fuel gauge stays pegged and is intermittent in telling me how much fuel I have left.

Also, if I'm using a Rotary tool, how big a bit should I be using, and also for putting in the trap door, what is the drill bit size and bolt size for that as well?

Does anyone have a writeup with visuals?

 

https://ls1tech.com/forums/fueling-injection/453249-fuel-pump-top.html
This should help. you do have to take the line's off. this is the only way I will ever do it.

 

So what I do is unbolt those 5 bolts for the fuel pump itself, take that out, remove the sending unit, then just replace?? Or do I have to disconnect vapor lines and all that junk??

 

What year car do you have? Cause if it is 98+ there ain't any bolts holding anything together with regards to the fuel bucket.

On 98+ you have to first mark out and cut your access door as shown in the many threads about this. You can use a Dremel with metal cutoff wheel - but you must be VERYcareful to only allow the wheel to just penetrate the sheet metal thickness - any deeper and you risk either cutting into your tank or lines.

Once the opening is cut, you'll see the top of the fuel bucket. You will need to disconnect (3) fuel lines from the left side, (2) wires from the front. The you will have to use a brass drift and hammer (no sparks here!) against one of the tabs on the metal fuel bucket retaining/locking ring to rotate it CCW till the ring tabs clear the corresponding tabs on the tank.

Then you can pull the entire fuel bucket out of the tank. Again being VERY careful as you are getting near the end to thread the float on the end of the sending unit arm out of the hole in the tank without catching or bending the arm. You will have to rotate and tilt the fuel bucket as you pull out at the very end to do this. Much better to have tank near empty when doing this - but even then, there will be fuel in the bucket that will spill out as you are tilting so as to not ruin sending unit float/arm.

Hate to be the bearer of bad news but, as far as replacing sending unit on 98+ cars - I'm fairly sure that you can't buy the sending unit seperately from the entire fuel bucket assembly - at least not from GM. The fuel bucket assembly is one part number and includes: fuel bucket with sending unit attached, fuel pump, corrugated fuel hose between bucket and pump, wiring between bucket and pump, and interior fuel sock.

I have the F-body GM Factory parts list on DVD and none of the individual parts are listed as individual part numbers - only one P/N for what I described above and one for the external fuel sock on the outside bottom of bucket.

I have already tried to order seperate parts from bucket assembly at my favorite dealer that gets me all my parts @ cost - not available. Entire FB assmy ain't cheap either

Once you get the bucket out, you may be able to see where the sending unit is damaged. it uses VERY teeny tiny contacts on the float arm that swipe over a semicircle pattern of electrical contacts on the sending unit body (like a rheostat). If those contacts on either side are damaged - you're screwed. If the arm is bent - you may be able to bend back into correct position. Or clean the contacts with contact cleaner. In any event, whatever you do - be VERY careful not to damage the contacts as I described.

I find it hard to believe that the sending unit is damaged unless someone has previously removed the fuel bucket incorrectly. The sending unit itself is very reliable in normal operation and hardly ever just goes bad.
-Jay-