Tom Carter Posted May 5, 2015 Share Posted May 5, 2015 Hey Guys, I was dealing with a fuel gauge concern last fall and just didn't get much time to check it out. I changed my cluster over to a gauge cluster last year. all the gauges are working except the fuel gauge. I can't tell you if the fuel gauge failed before or after I put the new gauge in. I can tell you about five years or so ago I changed the sending unit because it would not read above half. The new sending unit did not fix that problem but it worked correctly after half so I let it go. Now the gauge just pegs past full after the ignition is turned on. I disconnected the wire that feeds the sending unit (brown I think) and the gauge will then go to empty. I can do a full sweep with the gauge itself. Every thing I have done leads me to think the sending unit failed. I would hate to drop the tank for a hunch but of course I will. I was hoping to get the opinions of the greatest Monte minds to help me save a little time. By the way, I changed the cluster due to a recommendation by a few guys in the club. I love the look of tach in the cluster. I had one mounted on the steering column. I could't be happier with the change over. as always...thanks for all the help Quote Link to comment Share on other sites More sharing options...
Rock Posted May 5, 2015 Share Posted May 5, 2015 If the gauge pegs full on start up and stays there you definetly have the 12vdc at the gauge. Next ohm the brown wire from the trunk to the connector at the gauge pod and see if you have good continuity. If that checks out then you will have to drop the tank and replace the sending unit. I had to replace mine since mine would peg full all the time. After replacement of the sending unit it works awesome. I ended up replaceing the tank,straps and sending unit since I had it out and made it look pretty.....You know the snowball thing these guys always talk about. Any ways I checked my sending unit with an ohm meter and mine tested open curcuit. Yours may be hald open or half shorted. Good Luck. Quote Link to comment Share on other sites More sharing options...
Tom Carter Posted May 5, 2015 Author Share Posted May 5, 2015 I did check the brown wire for continuity. I even tried using a jumper from the sending unit to the gauge using test leads. I attempted to put a gauge in series with the curcuit as well and found the cluster gauge was reading less but still past the full mark. I was assuming the test gauge was pulling slight resistance. I suppose I need to just bit the bullet and replace the sending unit. The good thing is they are not to expensive I guess. Thanks for the assistance. Quote Link to comment Share on other sites More sharing options...
Rock Posted May 5, 2015 Share Posted May 5, 2015 Yeah...I tried using a dummy sending unit also before I dropped my tank and for some reason it made no difference. The sending unit I tried was used and bad also but I assume you could order a new sending unit and ground the unit to the frame and connect the brown wire to it and it should in theory work as if installed. good luck....It is a pain to drop the tank....thats why when I did drop it I made it worth my while and made things look good too. http://www.firstgenmc.com/forums/index.php?/topic/13247-new-tank-question/page-2 Here is my thread on replacing the tank,sending unit and straps if interested. Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted May 5, 2015 Share Posted May 5, 2015 I assume you checked the ground where it mounts to the body and at the cluster. I havent had a guage working in mine fir 7 years now By the way the house looks great. See you around soon I hope. Quote Link to comment Share on other sites More sharing options...
Tom Carter Posted May 5, 2015 Author Share Posted May 5, 2015 Stalker Steve...when did you look at the house. I did check the grounds but I am not to enthused about dropping the tank. I have half a though of replacing the tank and sending unit just so it is all new. Are you heading to Norwich on Memorial day? Quote Link to comment Share on other sites More sharing options...
Rock Posted May 5, 2015 Share Posted May 5, 2015 Heres a good look at the new tank.....Just to entice ya a little..... Quote Link to comment Share on other sites More sharing options...
Tom Carter Posted May 5, 2015 Author Share Posted May 5, 2015 That does look great too. Did the new tank have the interior splash baffles so when you take off there isn't fuel hitting the licence plate? That is a very convincing picture...you car looks great on the bottom picture too. Quote Link to comment Share on other sites More sharing options...
Rock Posted May 5, 2015 Share Posted May 5, 2015 Not sure on the baffles, I bought the Canadian one on recommondation from the guys on here. My car is a Van Nuys car so it has the 3 vent lines and the charcoal box under the hood. Yours may be different. Quote Link to comment Share on other sites More sharing options...
Tom Carter Posted May 5, 2015 Author Share Posted May 5, 2015 Yeah...The 70 didn't run a charcoal canister so I only use the one line. Either way it looks great. You didn't paint it at all prior to installation or did you spray it silver Quote Link to comment Share on other sites More sharing options...
Rock Posted May 5, 2015 Share Posted May 5, 2015 http://www.ebay.com/itm/70-Chevelle-Monte-Carlo-Fuel-Gas-Tank-Straps-3-Vent-Pipes-GM34G-Spectra-/331342477814?fits=Year%3A1970%7CModel%3AMonte+Carlo&hash=item4d258cf9f6&vxp=mtr My 70 has the charcoal canister.....Thats why I needed the 3 vent line tank. I ordered the Spectra tank. And My sending unit had the 2 lines on it, one was a return line(you may not have that either). Make sure you order the float that has the black plastic float and not the white foam one...those I hear suck. Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted May 5, 2015 Share Posted May 5, 2015 Tanya put a picture up on fb of the house. I always forgot about norwich because Lisas cousin usually has a picnic that day but not sure if she is this year. I'll check and let you know. Will the tank fit past the hitch or is it gonna finally go. I put a hitch on mine but just lttle one. Quote Link to comment Share on other sites More sharing options...
72-CLASSIC_RIDE Posted May 5, 2015 Share Posted May 5, 2015 I have had problems with my fuel gauge pegging out to about the 3:00 o-clock position. BUT, after I drive it awhile, the gauge starts operating properly again. This issue happens when the vehicle has been stored for prolonged periods. In my case, I believe the float arm sensor has lost contact with the sending unit, maybe corrosion, dirt or other debris. When I step on pedal during take off, the jolt and jostling of the fuel I believe gets contact from float arm back to sending unit. Calculating what I believe was gas in tank, I then filled it and compared amount pumped. Fuel gauge as close as I can see is accurate. So again, in my case, simply letting vehicle sit for long periods is enough to cause fuel gauge not reading (lost contact due to Sending unit/Float contact malfunction). Been doing this for years and cant remember ever having this problem when being driver on a more regular basis. One day I may have to deal with it. But for now, as long as I can use this trick to get it going again, that's what I will do. If your problem resembles this one, you might try this just to confirm. If it works, then your good until it works no longer. Doug Quote Link to comment Share on other sites More sharing options...
MC-71 Posted May 5, 2015 Share Posted May 5, 2015 Where did you buy the gauge cluster? Did it come from the Muscle Factory? If it did you might want to call them. Their fuel gauges had problems and the hide the problem. That was a few years ago. Quote Link to comment Share on other sites More sharing options...
my72toy Posted May 6, 2015 Share Posted May 6, 2015 I have just experienced the same problem. I installed a conversion kit that I bought from sonnie24 on ebay. After installing it I noticed that the gage would show 1/4 tank more than was actually in the tank. The other day I finally filled my tank completely full at the gas station for the first time. When I did that, the needle moved about a 1/4 tank more above the full level. Now, for the last couple of days, my needle is stuck sitting at about the 3 oclock position. When I got the kit from him, I noticed that the fuel gage needle was sitting past the full mark, I just assumed it had moved there because of the shipping and being banged around so I just moved it to about the 1/2 mark before I installed it. My old big fuel gage worked fine without any issues. Am wondering if I have a defective fuel gage now. Any ideas? Quote Link to comment Share on other sites More sharing options...
Tom Carter Posted May 6, 2015 Author Share Posted May 6, 2015 The cluster gauges all work good other than the fuel gauge and I am just leaning toward replacing the sending unit. if nothing else I can buy it and test it before I drop the fuel tank. The tank will come out with the hitch installed Steve but I need to have enough of an angle to drop it down and the slide it back. it needs to drop down further than the differential. If yours is a class one hitch instead of a class three you be in better shape even as far as tank removal. By the way I was kidding about the stalker Steve thing...I do forget she is on facebook though. Well hope to see you and Lisa in Norwich. Quote Link to comment Share on other sites More sharing options...
John S Posted May 6, 2015 Share Posted May 6, 2015 Ground the brown wire and gauge should go to Empty. I had trouble with mine replaced sending unit 3 times until I found NOS gauge. John S Quote Link to comment Share on other sites More sharing options...
Tom Carter Posted May 6, 2015 Author Share Posted May 6, 2015 Good deal...thanks for the help. I don't think I have done that as of yet Quote Link to comment Share on other sites More sharing options...
Tom Carter Posted May 18, 2015 Author Share Posted May 18, 2015 Well for all those who read and gave advice I say thank you. After checking the operations of the harness wire and the gauge I have confirmation that the sending unit is toasted. I did order a replacement sender with the black float. It came a few days ago and I was able to test the gauge with the new sending unit. It worked to perfection. Now I just have to install that bad boy and its off to the races. Thanks again for all the advice and help. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted May 18, 2015 Share Posted May 18, 2015 now here's something else to keep in mind..... if you tank is a factory original, the filler neck goes about half way into the tank, some of the aftermarket sending units have the float on the wrong side so the filler neck interferes with the float some have been successful with just bending the float the other way so it clears the filler neck just keep this in mind when installing the sending unit into the tank, the last thing you want... is to have to pull the tank again Quote Link to comment Share on other sites More sharing options...
Rock Posted May 18, 2015 Share Posted May 18, 2015 He thinks he is just replacing the sending unit.....lmao! Quote Link to comment Share on other sites More sharing options...
my72toy Posted May 19, 2015 Share Posted May 19, 2015 Ended up changing my sending unit and it has turned out to be a nightmare. I bought a replacement unit and put it in. When I filled up my tank after replacing unit, gas gauge only went to 5/8 tank. So I went back to my supplier and showed him the problem. He gave me a replacement unit to put in. So I went and pulled the unit out of the tank and compared it with my old non-working unit. The float arm is bent different than my old one. The new replacement unit he gave me will not work for me as the float is on the wrong side and will hit the filler tube inside tank. So I end up bending the float to try and match it to my old one. Reassembled everything and filled it up with gas, Now it only shows 3/4 tank when full. So I have ended up repairing my old unit, will be putting that back in this weekend. That will be the third time I have dropped the tank. Am getting real good at doing that now, lol Quote Link to comment Share on other sites More sharing options...
Tom Carter Posted May 19, 2015 Author Share Posted May 19, 2015 would that cause the fuel gauge to only show half way even though it is full. my gauge use to read half until it reached that point and then read correctly. I was told it was a baffle to prevent splash Quote Link to comment Share on other sites More sharing options...
my72toy Posted May 20, 2015 Share Posted May 20, 2015 The problem with the unit I got was that the float arm itself was too long, thus it would require a longer stroke for it to read from empty to full. As our tanks are not that deep, I could have adjusted the arm so it would read empty correctly but then it would not read full correctly, or vice versa. I have the original tank in my car if that makes a difference or not. And also make sure that the sending unit you have has the float arm on the correct side, as my filler neck extends deep into the tank and it would interfere with the float arm if it is on the wrong side. Hope this helps you out some. Quote Link to comment Share on other sites More sharing options...
Tom Carter Posted May 27, 2015 Author Share Posted May 27, 2015 So the new sending unit is installed. I looked at the one I took out. The float looked like a small clear plastic barrel. I went to move the float arm and it was just completely stuck. I forced it and something in the gauge sender snapped and then rattled when I shook it. The good news it the new sender seems to be built better and now I have full range of the gauge. I tested it out Sunday with a two hour ride to a Car show. Needed to represent the car club. Thanks again to all. Hope to see more of you guys this summer at the shows. Quote Link to comment Share on other sites More sharing options...
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