VickyBlue Posted February 11, 2012 Share Posted February 11, 2012 I removed the fuel gauge from the cluster. I applied 12V to the IGN terminal at the back of the gauge and grounded the SENDER terminal. Needle did not "jump". Then I flipped the gauge over, and applied the 12V to the inside of the same threaded stud, right by the thin wire and did the same with the sender post. The needle jumped to full. There is a red warning tag at the back of the gauge saying both the key-on power wire and sender wires should never touch the gauge, or it will get gamaged instantly. There is also a rectangular plastic plate that prevents the wires from touching the case of the gauge. I am ordering a new gas tank with a new fuel sender from tanksinc and want to make sure the gauge works. I read the test procedure from the service manual, but don't understand why I am not getting power to the gauge. I do get power once the 12V is applied inside though. What am I missing? Shouldn't the needle jump with key on power and grounded sender terminal? I assume the sender will need replacement, but I will know for sure once the gas tank is off the car. Also, does anyone know if the fuel sender pick up tube size is 5/16" or 3/8"? I tried to drop the tank but the L side exhaust was in the way and likes like I will need to make cut. Thanks for helping a newbie... Link to comment Share on other sites More sharing options...
JohnD1956 Posted February 12, 2012 Share Posted February 12, 2012 The fuel line all the way through the sender should be 5/16" Can you post a picture of the back of your guage? Link to comment Share on other sites More sharing options...
VickyBlue Posted February 12, 2012 Author Share Posted February 12, 2012 I will remove it again and post a picture on Monday when I get home. Thank you Sir! Link to comment Share on other sites More sharing options...
Leif Holmberg Posted February 12, 2012 Share Posted February 12, 2012 Most of the time the problem is in back of the gauge,the construction isn`t very good,You need to clean all the contact areas from inside to outside,otherwise you don`t get the contact as needed.Try to look at this problem at first.To check the sender you can use a Ohm-meter.Every electrican has one,and they are not very expensive. Leif in Sweden. Link to comment Share on other sites More sharing options...
Budd Posted February 12, 2012 Share Posted February 12, 2012 Most of the time the problem is in back of the gauge,the construction isn`t very good,You need to clean all the contact areas from inside to outside,otherwise you don`t get the contact as needed.Try to look at this problem at first.To check the sender you can use a Ohm-meter.Every electrican has one,and they are not very expensive. Leif in Sweden.Speaking of cleaning contact areas, the ground wire back at the sender unit is also problematic. You can have a perfectly good functioning gauge, but it will seem inoperative if the ground wire is not secured properly (had this happened to me, and my gauge would only work when it rains! -- found the ground wire was deteriorated and not making good contact)Cheers,BuddPS - I like your tagline VickyBlue. Link to comment Share on other sites More sharing options...
VickyBlue Posted February 13, 2012 Author Share Posted February 13, 2012 My understanding is (from my VW experience) if I apply 12V to the power post and ground the sender post, the needle should jump to full. At least this is what happens when I do this with my spare VDO electric fuel gage. This is the gauge out of the car:This is the back of the gauge showing the tag I was talking about:The inside of the gauge case:The back of the gauge unit itself, showing the IGN and sender posts:Showing the coil wires, attached, the needle moves freely by hand:Again, the posts are clean:Inside of the case, cleaned up:Back view of the case:When I apply power at the "blue" spots, the needle "jumps" to full.This is the only time it does. When I apply it at the posts, with the gauge in its case or outside the case, I am getting no power. I understand about the sender's connection in the system, but I am assuming the sender is inop. I tried to drop the tank but the exhaust is in the way and I have to make a cut. There is gas in the tank, about 10 gal worth of it, it leaks from the seams and the neck, (there is some kind of epoxy putty around the seams and the bottom of the filler neck), so at this point I am just checking the gauge. It seems to me everything is clean, there is no rust, shouldn't I be getting the needle to jump with power and ground at the posts? The next step will be to get the new tank and sender, install the gauge back in the cluster, and run a wire from the sender terminal to the sender and another wire to a ground and play with the "arm" see if the needle moves this way... What am I missing here? Link to comment Share on other sites More sharing options...
JohnD1956 Posted February 14, 2012 Share Posted February 14, 2012 I wish I knew more about electronics but I never studied this stuff. Section 10-81 of the 56' manual states the needle is moved by changing the magnetic pull of those two coils. The magnetic pull is changed by operation of the rheostat on the pickup arm in the tank. While I looked closely at the picture, I can't see where the two connector studs attach to the two coils inside the guage. Are you certain you have connections there? Link to comment Share on other sites More sharing options...
VickyBlue Posted February 14, 2012 Author Share Posted February 14, 2012 The studs are pressed in. There is a metal tab between the stud and the frame of the gauge that the thin coil wire attaches to. Red for the power and gold for the sender. The power tab connects to the thin wire.Now under the gauge, where the sender stud is pressed in, there is no tab... neither inside the gauge, nor outside... I can see the round portion at the base of the tab, but that is all there is... it is the right one. The tab should connect to the thin long strip right between the threaded studs... This might be the issue... tab is broken, not getting grounded.... I read page 407 (10-81) and unless the gauge works together with the sender as a unit, I don't know what else to think... I just ordered a new tank and sender and when they get here I will test the gauge with the new sender just like the manual says to. Thank you so much for pointing this out... Link to comment Share on other sites More sharing options...
Leif Holmberg Posted February 14, 2012 Share Posted February 14, 2012 I measured a spare gauge I have but not 100% sure it`s okey I don`t have a sender to test with,but here are the resault. Leif in Sweden. Link to comment Share on other sites More sharing options...
VickyBlue Posted February 15, 2012 Author Share Posted February 15, 2012 Tack så mycket Leif... The pink wire that goes to the sender unit shows 12.5 Ohm. There is gas in the tank, so the sender might be working after all... The gauge shows 0 Ohm on both terminals. The speedo cluster acts as ground for the fuel gauge. I grounded the fuel gauge to a different ground, (just in case the speedo itself wasn't grounded properly). Then I re-connected the wires, IGN and sender. The IGN showed 12.3 VDC, the sender 0. Then I put the multimeter probes inside the gauge, by the tabs and BOTH tabs (IGN and Sender) showed 12.3 VDC... I am done for today... Link to comment Share on other sites More sharing options...
JohnD1956 Posted February 16, 2012 Share Posted February 16, 2012 I am no expert on this but it appears the sender threaded terminal is not alive till the guage is mounted in it's case. Looking at the photos of the back of the guage I see the two threaded studs and the center smooth button. It appears from the other photos that the ignition stud leads directly to the red coil by virtue of a metal strip on the inside of the mounting plate for the threaded studs.It also looks like the wire from the gold coil comes back to the tab which is attached to the metal bar you see when looking at the guage from the rear. Looking at the case for the guage it is obvious that both the threaded terminals and the center smooth button go through the case. It also appears that the center smooth button will contact the case and by virtue of that contact, provide a ground through the back of the instrument cluster. What is not clear is if the metal bar shown on the back of the terminal also contacts the case. Now I do not profess to know why this is built this way. But it would seem if you hook your power source to the ign terminal and then your negative lead to the smooth center button, you'd have your complete circuit. But I would be careful about applying straight 12 volts to the guage. It's not the volts so much as the amps. I thought the guages had a 10 amp fuse in the fuse box? So I would be careful about the source of your 12 volts lest you burn something inside the guage. And then again, not having any real life study in this stuff I could be completely wrong about that.If I am right and if you do have a working sender unit, I did notice that the wiring diagrams for the 56 shows a fuel guage relay in the circuit. It is connected to the neutral safety switch in the automatics and directly to the regulator in the stick shifts. This may be the source of the inoperative guage. Link to comment Share on other sites More sharing options...
1957buickjim Posted February 16, 2012 Share Posted February 16, 2012 For what it is worth, I bought a 12 volt power supply from Radio Shack. I think it only provides 3-5 amps, but for this kind of work it might be worth it. I think it was $25. Beats hauling around a battery and plugs right in to the 110 outlet in my shop. It is about the size of a paperback novel. Link to comment Share on other sites More sharing options...
VickyBlue Posted February 16, 2012 Author Share Posted February 16, 2012 This is what I am dealing with... The neutral safety switch has 4 terminals, according to the manual: 1 2 3 4. Only 1 and 2 have wires and the colors do not match. 3 and 4 have no wires going to them... Link to comment Share on other sites More sharing options...
1957buickjim Posted February 16, 2012 Share Posted February 16, 2012 Oh Boy! Was the car rewired by you or before you bought it? Do you have a chassis manual for the car with a wiring diagram? That would help immensely. At least you could trace the wires from point to point with the colors. Link to comment Share on other sites More sharing options...
VickyBlue Posted February 16, 2012 Author Share Posted February 16, 2012 The car was rewired by the PO. The thing that blows is that almost none of the wire colors I am dealing with matches the 56 chassis manual that I have... Things that do not work are: the clock, the fuel gauge, the speedometer/odometer and radio. All other lights including the dome light work... The ignition switch "flips" and there is a push-start button under the dash. Link to comment Share on other sites More sharing options...
55 SURVIVOR Posted February 16, 2012 Share Posted February 16, 2012 HELLO;I'm not sure of your original problem,but if the gauge goes to full when the key is on you have a bad ground,mine was at the sender,it has only 1 wire to it,and grounds with the mounting hardware/tank mount/frame.I ran a seperate wire from the sender to the frame,works fine.The gauge measures "resistance" from the sender in relation to level of fuel/copper windings in the sender.If there is no gauge movement you may have a broken wire to the gauge,if you blow a fuse there is a short.I ran a seperate test wire to the gauge to check that,from the tank sender.you can also check the gauge with another,i pulled one from my boat to check it.A bad ground is very common on old cars.I hoped i had shed some light on it,good luck!! Link to comment Share on other sites More sharing options...
JohnD1956 Posted February 16, 2012 Share Posted February 16, 2012 (edited) Well, this changes things a bit. I took another look at the wiring diagrams in the manual and must make two corrections. There is no gas tank relay. And it appears there is no fuse for the gas guage. I apologize for incorrect information, but I think we can still help you get this working if your parts are still good. Here's what we need to know first. Do you still have the generator/ and voltage regulator, on the drivers fender, or has this been swapped out for something newer? Edited February 16, 2012 by JohnD1956 (see edit history) Link to comment Share on other sites More sharing options...
old-tank Posted February 16, 2012 Share Posted February 16, 2012 This is what I am dealing with... The neutral safety switch has 4 terminals, according to the manual: 1 2 3 4. Only 1 and 2 have wires and the colors do not match. 3 and 4 have no wires going to them...Yikes! Most aftermarket wiring kits have the individual wires identified. It looks like a lot of green wires in that setup...The neutral safety switch on my 55's has 2 terminals used for the safety start function and 2 terminals used for the backup lights.Willie Link to comment Share on other sites More sharing options...
1957buickjim Posted February 17, 2012 Share Posted February 17, 2012 VB..Do you have any idea why they re-wired the vehicle and put this fuse panel in? Did the car have an electrical fire or something? I would still try to get a 1956 Wiring Diagram and start with that. I don't think it is much different than the 1957, but it would sure help you out in unraveling that bird's nest. In my vehicle (1957) the neutral safety switch wire colors to the numbered terminals are:1 - 18 ga. Black - Back Up Lamps2 - 18 ga. Lt. Blue - Brake Warning Lamp / Switch3 - 18 ga. Pink - to Ignition4 - 18 ga. Yellow - to Accelerator Switch (Carb)Hope this helps to figure that out. Link to comment Share on other sites More sharing options...
buick5563 Posted February 17, 2012 Share Posted February 17, 2012 Jimbo, A shop manual isn't gonna help. He needs to know how the manufacturer of the harness colored their wires. I just put one of these aftermarket harnesses in, and at least it is labeled (printed) the whole way. Good luck VickyBlue. I imagine that at least it is kinda sorta safer than the original wires. Keep at it... Link to comment Share on other sites More sharing options...
1957buickjim Posted February 17, 2012 Share Posted February 17, 2012 Mike,Thanks..Just from the pictures it looked to me like a combo platter of new wires and original wires which makes for a kind of mess in the installation and firguring it out, especially if you have no history of what was done and why. I know that you and Bill just did his 47, and BTW a great job there. Just thought having the diagram might be helpful. Probably can't hurt. VickyBlue..Mike is right about keeping up the work. It will all come together. Link to comment Share on other sites More sharing options...
VickyBlue Posted February 17, 2012 Author Share Posted February 17, 2012 John, it is the original generator with the regulator at the L side fender.I don't know why the fuse box was replaced... there were no fires. The car was originally dover white/castle gray. Frame is bedlined, firewall is color matched. No signs of damage. I would guess it was done as an upgrade, it is a "partial" wiring, there are still factory wires left, there are no heater hoses under the dash, (which it kind of makes it easy to get my hands under there) the carpet is new, the interior is new, the windows were not removed for the respray. I am almost done with my 66 ghia, I have about 4-3 days worth of interior work (between work, the house, the better half, and two girls 7 and 5, I wish the day had more hours...) Once done, I will start working on the Buick. As far as wiring goes, will have to find what they kept and what was replaced... In my ghia, I ripped everything out and made my own. I do have a VDO fuel gauge I can use but I am afraid the sender will be out of whack, as it is calibrated for a VW. I though about using a Dakota Digital fuel gauge with a sender adapter, but I just don't want to quit, not yet. Thanks for all your help. Link to comment Share on other sites More sharing options...
JohnD1956 Posted February 18, 2012 Share Posted February 18, 2012 Okay. I noticed a hanging wire in post # 13 above, picture two. Is that your fuel guage power source? I assumed you verified that has 12 volts when the ignition is activated?I also assume you have tried to isolate which terminal of the two on the guage itself, is not making contact?As for the Neutral safety switch electrical connections, as per the wiring diagram on page 411 of the 56 manual:Terminal one is the switch for the back up lightsTerminal two is the switch for the parking brake light on the dash. Terminal 3 is an ignition wire. The schematic shows that this lead, and the gas guage igniton lead are connected together and to the #12 guage pink wire off the ignition switch.Terminal 4 is the lead that goes to one side of the carb starter switch. Link to comment Share on other sites More sharing options...
VickyBlue Posted February 18, 2012 Author Share Posted February 18, 2012 (edited) The pink wire is going all the way to the sender. It becomes brown at some point. I traced it with my fingers and goes to the side by the footwell and then towards the back. It is confusing and don't know why, but pink stands for IGN according to the manual. The pink wire, shows 12.7 Ohm with key-on and key-off, which tells me the sender might be OK.There was no power wire to the sender. I used the No 3 terminal on the ignition switch and verified it with the multimeter, key-on power, key-off no power. It is a 16 gauge wire, no fuse to it. So I know the fuel gauge is getting power from the outside of the case, then somehow inside the case the power is been transfered to the sender stud and the sender stud shows hot. My neutral safety switch has terminal three 18 gauge red, terminal four 18 gauge red and nothing on 1 and 2. Most of the wires are labeled though, this is something I just found out, I flashed some really bright light under the dash and saw most of the 14-12-10 gauge wires are marked from the harness manufactures. I will remove the fuse box see if I can see a name or something, but it will have to be next week. I will have to transfer their color to paper and superimpose them to the factory see which is which. But for now terminal 1 and 2 on the neutral safety switch have no wires, which makes sense, as there is no parking brake dash light and I bet there will be no back up lights. Edited February 19, 2012 by VickyBlue (see edit history) Link to comment Share on other sites More sharing options...
Guest NikeAjax Posted February 19, 2012 Share Posted February 19, 2012 Is this any help to you?Jaybird Link to comment Share on other sites More sharing options...
VickyBlue Posted February 19, 2012 Author Share Posted February 19, 2012 (edited) Is this normal? My VDO gauge does not do that... http://s412.photobucket.com/albums/pp201/2xxnoxy/?action=view¤t=IMG_0294.mp4I am also getting 12.3 VDC at the needle... The coils however are registering no power at all. The power stops at the tab and continues around the gauge via the gold colored part of the frame.Thanks Jaybird... Edited February 19, 2012 by VickyBlue (see edit history) Link to comment Share on other sites More sharing options...
Leif Holmberg Posted February 19, 2012 Share Posted February 19, 2012 Yes that looks "normal",that happen with my gauges too. Leif in Sweden. Link to comment Share on other sites More sharing options...
VickyBlue Posted June 10, 2012 Author Share Posted June 10, 2012 (edited) I fixed it! Spent all day today, it was a ground issue. The sender shaft's tab needs to be grounded. I don't know if it was with time the ground deteriorated, or anything else, but when I realized what it needed to be done, I soldered a 16 gauge wire to the bottom of the sender tab and attached the other end to a ground. Then I realized that some part of the gauge was "touching" the case and the needle was erratic. I used electric tape and tapped the bottom of both studs, IGN and sender, the round tab in between and anything that might be touching the case. That did it! Put everything together and I am a happy guy:) Edited June 10, 2012 by VickyBlue (see edit history) Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now