Mattmustangman1969 10 Report post Posted March 31, 2009 just a quick question, I am just putting in my new gauge cluster, and so far they all work good, except for the fuel gauge, basicly it has power and grounded, just when ever the key is on, it shows a full tank even tho i only have 8 gallons in it. now is this sort of reading mean a bad sender? Because if my thinking is correct, when i directly ground the sender wire to the frame it show the same reading, so therefore the fuel sender is directly grounding the wiring not using the resistor( or what ever it has) to adjust the level.... does that sound right? Matt Quote Share this post Link to post Share on other sites
Boogerschnot 12 Report post Posted March 31, 2009 (edited) yep, sounds right.. A empty reading should be between 8-13 ohms and the full one should be about 73 ohms.. Sounds like you need a new sender. Or check the little nut that is attaching the wire to the sender at the sender, you may have grounded the wire somehow. If the mounting nut came loose the bolt may have grounded itself against the side of the sender.. Pull the wire off of the sender and check it with an ohm meter to ground and see if your wire is somehow grounded.. Edited March 31, 2009 by Boogerschnot Quote Share this post Link to post Share on other sites
Jayru 17 Report post Posted March 31, 2009 Sorry to jack this thread. I've got a weird issue with my Fuel gauge. When the car is first started, it reads the correct amount of fuel in the tank, but as the car runs for 5 min or so, the gauge creeps about a quarter tank lower than the actual reading. So for example: the car starts up and shows 3/4th's a tank, then creeps down to a half. If you shut the car down, let it sit for a few minutes, then start it up again; it will read correct (3/4th's), till the 5 or so min goes by and it creeps down again. Any idea what this could be? I have a new sending unit in the tank. Thanks! Jay Quote Share this post Link to post Share on other sites
Pakrat 1,043 Report post Posted March 31, 2009 Sorry to jack this thread. I've got a weird issue with my Fuel gauge. When the car is first started, it reads the correct amount of fuel in the tank, but as the car runs for 5 min or so, the gauge creeps about a quarter tank lower than the actual reading. So for example: the car starts up and shows 3/4th's a tank, then creeps down to a half. If you shut the car down, let it sit for a few minutes, then start it up again; it will read correct (3/4th's), till the 5 or so min goes by and it creeps down again. Any idea what this could be? I have a new sending unit in the tank. Thanks! Jay New does not mean good, all reproduction parts should be verified first as a general rule. My guess is the float has a pin hole in it which is actually not uncommon on new senders believe it or not, particularly with the metal floats and not as often with a plastic float. As it fills with some gas it will sink below the surface giving you a faulty reading. Quote Share this post Link to post Share on other sites
Fly Boy 10 Report post Posted March 31, 2009 I was working on an old Cuda back in the day. Lady brought it to my brother in law's shop. It would run fine on anything above a 1/4 of a tank. Once it got below a quarter it would stall and restart if you let it sit for a few minutes. It would stall more often as the tank got lower but it would restart more quickly. Trouble shot everything we could think of and finally drained the tank. We found a ping pong ball in there that had been crammed down the fuel recepticle!! It floated on the gas and would get sucked down when below a 1/4 tank and would refloat when the positive pressure was relieved on the line!! Thnkgs that make you go hmmmmm. Now back to your regularly scheduled technical questions....... Quote Share this post Link to post Share on other sites
bcorbin 10 Report post Posted April 1, 2009 Matt, You might go to a radio shack and get some of their 10 watt resistors. They have 1, 10 50 ohm values so you can mix and match and get the 73 ohms and ~13 ohms mentioned above and test the gauge readings. If it reads correctly with the resistors to ground in place of the sender it would tend to point towards the sender. Another thought. You mention that the gauge has power and ground. I assume you mean power (12volts or so) is on one side of the gauge and ground is on the other. There should not be a direct connect to ground on the sender side of the gauge. The least is should be is that 13 ohms to ground from that side of the gauge. If that side of the gauge is truly at ground you have a short somewhere. It could be the at circuit board, the wiring somewhere or maybe at the sender. If you remove the wire connected to the sender does the gauge read all the way to "low"? With the sender disconnected completely there should be no current flow through the gauge and it shouldn't read anything. If it still reads "full" you have a short to ground somewhere. Good luck! I have certainly had my share of gauge troubleshooting fun in the past. Bret Quote Share this post Link to post Share on other sites
Mattmustangman1969 10 Report post Posted April 4, 2009 Hey, well I got a voltmeter and checked the sender it was reading 86 ohms at empty and 25 ohms at a full tank. so I went and bought a new sender and checked it out to be safe... it was perfect 73 and 13 ohms, but when I put it in the tank, the gauge would read half a tank, when there isn't any fuel in the tank, so my next questions is could it be the gauge. It is a autometer pro-comp(series) and the gauge is said to be the right ohms (via the part number), just curious if any of you have had this issue. is basicly the next step to buy a few resistors at radio shack and check it through the sender or is there a easier way? Matt Quote Share this post Link to post Share on other sites
