The Stovebolt Site Forums The Shop Area The Electrical Bay Gastank sending unit install, 54 1/2 ton

My gas gauge stopped working and, for whatever reason I ordered a new sending unit. Naturally it came with no instructions or info on wiring, so if anyone can steer me through this process I'd appreciate it. The tank is behind the seat and is original. Does the tank need to be empty (installing from bottom)? Thanks.

a 54 pickup sending unit installs in the top of the tank, there is no way to install it from the bottom .... remove the wire[s] from the sender, remove the screws, pull the old sender out, replace with the new one, reinstall screws and wires, the wire from the post terminal is to the gauge, good idea to check the continuity with an ohmeter - and it's usually a good idea to have a wire from one of the mounting screws to cab ground to insure the sender is getting a good ground

Bill

I would suggest wiring up the sending unit to the fuel gauge and a good ground (to the sending unit bolt flange) before installing the unit to make sure that the gauge goes from empty to full as you move the float arm up and down. This will allow you to make sure that your problem is actually the sending unit rather than the gauge. Also as you insert the sending unit in the tank, make sure the float doesn't contact the side of the tank, and bend the arm if necessary to prevent the contact.
Carl

Thanks, guys. I switched the wiring on the gas gauge, and now the gauge registers full (the tank is full) so I guess I need to drive it to see if the gauge drops correspondingly to the gas being used. If not, it may be a ground issue. It is grounded from the gas gauge post that also has the wire that goes to the sender, to the dash. Does that sound right?

Not at all!

So then the ground goes from the power gauge post to dash?

Stephen, DO NOT attach a ground to the power terminal, that's called a "direct short", grounds are attached to the case .... checking the sender out of the tank you need to have a ground from the mount flange of the sender to the truck [or dash], and you could/should have a ground from the case of the gauge to the dash to insure the gauge itself is getting a better ground than it may be getting from the mounting

Bill

Stephen, in the picture posted by Bill: You need a wire connected under one of the mounting screws on the flange to a good ground.
Then the top terminal goes to one post of your gauge. The other post on your gauge should be hot when ignition is on. NEVER put a ground to this post or the top terminal on the sending unit.

Well guys, I wish I'd waited for responses but being a ready, fire, aim, kind of guy I started experimenting with different connections last night,ending up with the one that caused smoke. (ground on post). I had some areas of the ignition wire that were melty and wrapped them in electrical tape. Today I put a runtz on, first trying it on the E terminal with the sender on the F and ground to dash but got no gauge response with power on and cranking battery. I assumed the battery was low and charged it with my other car. No change so I switched the runtz to the F terminal, grounded to the bottom of dash, and the sender wire on the E terminal. Unfortunately the engine still just cranks but won't turn over and the gauge does not respond, fortunately there is no more melting. At least I haven't put in the new sending unit yet. Should have left well enough alone but I'm not that smart, so tell me, how screwed am I? I cant figure out why it won't turn over, power runs from a fuse box and they are intact. As always, thanks for the help.

Your gauge is likely fried

I would pull out the cluster, inspect your wiring, replace all the damage.


Get a new gauge and test on a bench before you reinstall the cluster.


You do not ground any of the post on the back of the gauge.

I'm going to replace the wiring. I'm hoping that when I bought the gauge cluster originally I got a 12v gauge and that it might have survived my screw up. If that is so then I don't need a voltage reducer and I can hook the hot wire to the F terminal, which is the lower one on the 54, the sender to the E terminal and ground from the gauge housing mounting screw to dash. Just hope I didn't ruin something else that is preventing the engine from turning over.

Here's Lonniec refurbished gauge

http://s149.photobucket.com/user/lo...%203100/Gauges/GaugeHousingBack.jpg.html

The post with the red tag gets the sender.

The gauge grounds by being mounted to the dash. Not addition grounding should be necessary.