LenRobertson Posted June 11, 2017 Report Share Posted June 11, 2017 That came out pretty clean. My tank and unit after sitting looks just as clean as thT. The as why I can't figure out why my it doesn't register. I was wondering during if the temp and fuel work together cus I disconnected my temp to put a guage in I just went out to my '72 510 and pulled the wire off the temp sender at the thermostat housing. The fuel gauge still works fine. Both fuel and temp gauges are powered through the same gauge voltage regulator but each gauge then has its own ground wire out to its sender. The sender is actually a variable ground. The way to test your fuel gauge is unhook the wire from the sender at the tank. Use a jumper wire to hook the sender wire to ground. If the gauge is working properly it will read Full. Sparks won't fly when touching the sender wire to ground because it is actually a ground wire. If it reads Full when grounded but the gauge doesn't work when hooked to the sender, likely your sender is bad. Len Quote Link to comment
edekalil Posted June 12, 2017 Author Report Share Posted June 12, 2017 Sending unit seems to be fully functional. So I guess I'll clean the rest and see how it all goes. 2 Quote Link to comment
crewy Posted June 14, 2017 Report Share Posted June 14, 2017 OK Len I tried doing that and it still didn't work. That means the unit in the tank maybe bad from what your saying. Would changing the Alternator to a internal instead of a external change the difference of the gauges. There shouldn't be any difference between the 68 then the 70s guages Quote Link to comment
datzenmike Posted June 14, 2017 Report Share Posted June 14, 2017 Are there two wires to the tank? The other may be a ground and if that is broken there is no ground connection. If just a single wire it is grounded through the tank... try running a good ground to the tank and see if that works. If not than the sender is broken or stuck. Quote Link to comment
edekalil Posted June 15, 2017 Author Report Share Posted June 15, 2017 Now to do the same to the other sedan sending units and see how it go's. Quote Link to comment
LenRobertson Posted June 15, 2017 Report Share Posted June 15, 2017 OK Len I tried doing that and it still didn't work. That means the unit in the tank maybe bad from what your saying. Would changing the Alternator to a internal instead of a external change the difference of the gauges. There shouldn't be any difference between the 68 then the 70s guages You are saying you pulled to wire off the tank sender and connected the wire to ground and the fuel gauge didn't move? I want to be sure I'm clear on what you did (and morning coffee hasn't kicked in yet so I'm struggling with getting my brain to function!). Be certain you have a really good bare metal ground when you do this. I just went out to my 510 and tried another test - with the key in ON position my fuel gauge works. I went back and pulled the wire off the sender at the tank. Then I put a test light between the sender wire and ground. The test light lights up (although unexpectedly it blinks off and on. datzenmike - remember we were talking the other day on how often the gauge voltage regulator points make/break contact? Maybe there is another explanation for the blinking test light but the regulator is the only thing I can think of). So if your gauge doesn't move when the sender wire is grounded and you don't get a light when hooking a test light from the sender wire to ground, you must have a problem elsewhere in the gauge circuit. When you turn your key to ON position, do the oil pressure and alt lights light up (although if you have aftermarket gauges the lights may be unhooked)? If they light up this is an indication of power to the dash circuit. I don't see any reason going to an internally regulated alternator would bother the gauges any. They should still be getting the same voltage. I have a 280Z int. reg. alt on my 510 and the gauges work. Len Quote Link to comment
edekalil Posted June 16, 2017 Author Report Share Posted June 16, 2017 I think I will spray or coat this sending unit with some Tuf Glide not sure if it would help stop any rerusting of it but it should not hurt it. Now the question is do I use the old O ring that looks flat or get a new one. Any ideas what and where to get it? Quote Link to comment
Crashtd420 Posted June 16, 2017 Report Share Posted June 16, 2017 I bought these off ebay..... 1/8 thick... seems to fit good... and was rated for gas. I've seen some for zcars online too and some have said take it to Napa and match it up... but napa near me sucks so I don't bother.... Quote Link to comment
crewy Posted June 16, 2017 Report Share Posted June 16, 2017 Hey Len Ill try with the key on this time lol. All if my other lights light up when I turn on ignition. So Ill try with the key on. If it registers with it on the sending unit in the tank is bad. Quote Link to comment
edekalil Posted June 16, 2017 Author Report Share Posted June 16, 2017 I bought these off ebay..... 1/8 thick... seems to fit good... and was rated for gas. I've seen some for zcars online too and some have said take it to Napa and match it up... but napa near me sucks so I don't bother.... Thank you just got the same deal. Quote Link to comment
Crashtd420 Posted June 16, 2017 Report Share Posted June 16, 2017 No problem.... I enjoy helping and sharing what I find and learn.... That seller was really quick too ... Nice work on your sending unit.... Quote Link to comment
edekalil Posted June 16, 2017 Author Report Share Posted June 16, 2017 No problem.... I enjoy helping and sharing what I find and learn.... That seller was really quick too ... Nice work on your sending unit.... Why Thank You. Quote Link to comment
LenRobertson Posted June 16, 2017 Report Share Posted June 16, 2017 Hey Len Ill try with the key on this time lol. All if my other lights light up when I turn on ignition. So Ill try with the key on. If it registers with it on the sending unit in the tank is bad. Yeah, key on is much better! The problem with a test to ground like this is knowing whether or not the ground is really good. I plan to take a long piece of 14 gauge wire with an alligator clip on each end and make a test lead I can run outside the car to the battery neg terminal. Then I can feel more confident I really have something reliable to ground to rather than scratching around inside the trunk or under the dash trying to get a ground. If you have a test light, try testing between the sender wire (pulled off the sender) and ground. I'm curious if you (or anyone else who wants to try this) will get a blinking test light. I'm still not sure what is causing the blinking. It is worth running a jumper wire from the body of the sender to ground as datzenmike suggested. A lot of problems end up being bad or dirty grounds. The inside of my 510 tank and the entire sender were coated with brown varnish due to gas drying out in the tank. I used spray carb cleaner and Q-tips to clean the resistance coils on the sender and the wiper on the float arm. There is probably a continuity test that can be done on the coils but I haven't had one of the senders out in years and can't quite picture in my mind how to test this. Len Quote Link to comment
Tedman Posted June 18, 2017 Report Share Posted June 18, 2017 FWIW, New Datsun Parts has a new 510 sedan or Wagon sender for $99 if you just want to be done with it. http://www.new-datsun-parts.com 1 Quote Link to comment
edekalil Posted June 18, 2017 Author Report Share Posted June 18, 2017 Thanks for that info. I'll get mine out today, I let the other side clean up so It should be all clean now. I still have to deal with 3 sedan senders. So for now I'll hold off in case someone who really needs a working one they can use that info. It is very tempting I almost jumped on it. I will probably put some tuf glide on it, it may not help but I'll give it a shot, my guns haven't rusted since I put it on them. So for now I'll just let her bump. I'm way further alone than I was for now and it works. Quote Link to comment
Colbino Posted June 23, 2017 Report Share Posted June 23, 2017 ...and the unit to tank o-ring is still available from nissan for $2.48. p/n 17342-18000. Quote Link to comment
edekalil Posted June 25, 2017 Author Report Share Posted June 25, 2017 ...and the unit to tank o-ring is still available from nissan for $2.48. p/n 17342-18000. Thank you. Quote Link to comment
crewy Posted August 9, 2017 Report Share Posted August 9, 2017 Is there a way of testing the sending unit out of a tank. And should there only be one wire going to the unit which is a yellow color wire. Going to check the wire loom from guage to tank Quote Link to comment
Draker Posted August 9, 2017 Report Share Posted August 9, 2017 Check for resistance between the terminal and any metal on the face. Value should change as you sweep the arm. If it's open, then it's bad. If the value does change when the arm is swept, it's bad. Quote Link to comment
datzenmike Posted August 9, 2017 Report Share Posted August 9, 2017 Turn ignition to ON. Ground the sender wire back at the tank. Gauge should read FULL. Wiring from tank to gauge is working. When connected to sender and gauge does not read, make a separate ground for the tank. If still no reading the sender is bad. If gauge starts to work then the tank ground is bad. Testing the sender out of tank. Use an ohm meter. With float in the fully up position you should get 10 or less ohms. In the full down position 80 or more ohms. Quote Link to comment
crewy Posted August 9, 2017 Report Share Posted August 9, 2017 Was looking on the back of my cluster notice like a Lil box like a resister of somw sort. I can't load a pick of it but I have another cluster and it doesn't have one. My wiring is Virgin as hell to boot. No cut wires under dash so I'm gonna look at the local in car. Quote Link to comment
Draker Posted August 9, 2017 Report Share Posted August 9, 2017 Depends on the year. 68 may have has the voltage regulator. 69 did not. At least not on the back of the cluster. Quote Link to comment
crewy Posted August 11, 2017 Report Share Posted August 11, 2017 So does that mean there's also another voltage regulator behind the dash that could be bad on the 68 cuz that is what I have a 68 Quote Link to comment
datzenmike Posted August 12, 2017 Report Share Posted August 12, 2017 The gas and the temp gauges are run from the same voltage regulator so if one works, then the regulator is working. Quote Link to comment
crewy Posted August 31, 2017 Report Share Posted August 31, 2017 I looked on the back of the cluster and there's a Lil gold square resister near the fuel. I have Bother cluster that's a 69 and it doesn't have that Lil gold resister like my 68. Thoughts Quote Link to comment
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