finally got around to wiring my fuel gauge up but when i turn the key the needle moves straight to E and it has half a tank in it. did some adjusting on the new sending unit, gauge unit is new as well. is there an adjustment i have to do to the gauge? i have to dissassemble the cluster to put a new temp gauge anyway so if its that please help me out. All connections are solid and everything is brand new, has ground, etc.. Edit: the hot wire has never touched the sender terminal, so it shouldnt be damaged.
Last edited by Mr. Dane; 09/14/20192:27 PM.
Owner of the most temperamental 1951 3100 in existence
I find it best to hook up the fuel gauge before installing it in the tank, then run it from full to empty while watching the gauge. If it works, in the tank it goes, if not, it's much easier to figure out what is wrong. Aftermarket sending units are adjustable, they should sweep the entire length of the resistor ( full to empty ) in the hight of the fuel tank. As an example, my tank is 10" high, so to get the full range of movement, I had to shorten the depth of the sender about 4", and shorten the float arm 3"or so. There is some trial and error involved in aftermarket parts.
Fuel senders and gauges need very clean grounds at the sender to frame location. The gauge has power ( + ) running to it, the ground side of the circuit runs back to the sender, through the variable resistor of the sending unit, then to frame ground. Fuel level varies the amount of ground signal the gauge sees.
Double check that the sending unit has a ground wire securely mounted to it running to a freshly cleaned ground on the frame rail. As a side note, the battery should have a clean ground cable going to the frame rail.
ill ground it to the frame, we coated the inside of the tank so the mount screws might not have connection. even so i took it out and played around with it and it works but the gauge just reads E. ill try a ground and see what happens! edit: should i secure the gauge cluster so it has proper ground too?
Last edited by Mr. Dane; 09/14/20194:56 PM.
Owner of the most temperamental 1951 3100 in existence
Doesn't empty mean the sendor is grounded out? The problem I had was the sendor wire grounding out on the surrounding frame. Try loosening the sendor wire and moving it around while watching the gauge.
Greg, yes, you are correct. A fuel gauge that always reads empty can be caused by a short to ground in the wire to the sender, or the sender terminal being shorted to ground. A fuel gauge that always shows full is a symptom of an open circuit (ie, broken wire) between the gauge and sender. Good suggestion.
ive already ruled this out, could it be a gauge issue? or do i need to keep fiddling with my connections? for refrence, as far as i know, my gas tank isnt grounded whatsoever, the inside of the tank is completely sealed as for the fuel causing a issue i have my doubts. should i top off the tank first? perhaps filling it to maximum might produce a result?
Owner of the most temperamental 1951 3100 in existence
The tank being grounded and sealed has nothing to do with the way the sender works. The sender itself must be grounded to the frame.
There is a small wire that runs from top of sender down to the variable resistor that the float arm runs on, this wire could be grounded to frame of the sender or the insulated stud of the sender. The fellows in a few post back were explaining this and found it to be their problem.
Variable resistor, full ground signal = empty on fuel gauge. Less ground or none at all = full on gauge Dead short to ground = empty on gauge and needle never moves. A working system will always move the needle a little even when out of fuel. Open circuit ( broken wire or no ground ) the gauge will read full or pegged. A full tank of fuel will not peg the gauge.
If you haven't removed the sender from the tank, do so now.
Unhook the small wire and pull it away from the insulated stud, ground the frame of the sender with jumper wires, hook the wire from the gauge to the small wire you just unhooked, be sure it's not touching any part of truck or sender, turn key on run float arm from full to empty, Does gauge work? Yes / No
Unhook wire from sender, did anything happen? Yes / No Gauge should go full or pegged. Try tapping on gauge to see if needle is stuck.
ive already tried this and when i remove the wire going to the stud on the sender unit the needle doesnt move. when i place it back on the stud it moves the tiniest bit, i dont think its a question of my sender because it quite obviously works, but the gauge doesnt respond no matter what. could it be a problem of improper current or power going to it? perhaps it broke somehow already? ive had the gauge cluster apart multiple times and ive moved the gas gauge to make sure it wasnt stuck, perhaps i messed something up? 99% positive its the gauge not the sender.
Owner of the most temperamental 1951 3100 in existence
update: i fixed it. forgot to check the connection on the gauge itself! it wasnt making contact because of a washer, so i removed it. Also, good thing i took the float back out because sure enough it was full of gas, so i re sealed it. however we still have a slight issue, calibrating it. when i hit maximum threshold it goes all the way to full, but the float would have to be sticking out of the tank! is there any sort of compensation adjustment that can be made?
Owner of the most temperamental 1951 3100 in existence
As Joe said. Measuring stick and some careful bending will get it just right. You want the float to be at the bottom of its stroke at about 1/8 inch off the bottom of the tank. Good luck.ðŸ›
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
