Fuel/temp problem

[Sastis]

Post pictures if you can please.

[datzenmike]

Over heating would not cause the gas tank to read over full too.

 

You said when you give it the gas both readings go up. This would tell me your voltage goes up with the engine revs.  For example 12.5 v at idle and 14.5 v as you rev it up. This is the whole point of the temp/gas voltage regulator....to provides a constant 8v (or so) volts that are unaffected by the alternator charge rate.

 

 

As I understand it the 'regulator' is a bi-metallic strip that bends when warmed. There is a coil of wire around this strip and contacts on the end. Current flow warms the metal strip and it bends, opening the contacts. It cools, bends back and makes contact. Perhaps the contacts are stuck together or broken and not opening? It needs to be examined. If the contacts were not making contact both gauges would read zero.   

[racerx]

Also on the "how to" there's a thread about fixing the vr for a couple bucks.

[LenRobertson]

Post pictures if you can please.

I added another pic of the regulator on the gauge cluster to this Dropbox folder:

https://www.dropbox.com/sh/2y93icaof58g1q0/AABPhTfw_a88r8xfohSZVEGCa?dl=0

This still isn't as good a quality as I would like but maybe can help you see what the regulator looks like. I need to remember how to set the camera on manual focus to get what I want.

 

You will still need to remove your gauge cluster to get some idea what is happening with your regulator. In your post #21 showing the back of your gauges assembly, remove the 3 screws on the center circuit board (1 on the LH side and 2 on the RH side), not the four screws in the middle of the board. Then you can lift the gauge cluster out and take a look at your regulator. Since your gauges are pinning on high, my guess is your points are stuck closed. But I'm not sure if just gently nudging them open will be a fix.

 

Len

[crewy]

I have a 68 cluster that fuel n temp don't qork. I've been reading and some say the resister is behind the cluster. Clean the connection and may work or is there a way of testing them

[LenRobertson]

From reading other threads on gauge problems I get the idea that early 510s like yours had the voltage regulator for the gauges in a rectangular metal "can" mounted on the back of the instrument cluster, similar to the 521 shown in posts #2 or #10 here: http://community.ratsun.net/topic/66696-gauges-stopped-working/

It is worth reading through all that thread to get a better idea how the regulator works.

 

In this thread, post #7, datzenmike gives a part number for the regulator but it was posted in 2011 so may not be available any longer. http://community.ratsun.net/topic/30929-510-dash-gremlin/

 

If you don't have your instrument cluster removed yet, you can do a couple of quick checks first. Pull off the wire at the temp sender and/or the gas gauge sender at the tank. Use a jumper wire to connect the wire to a good ground. This should make the gauges pin on high temp/full tank proving you have a good circuit through the regulator and gauges to the sender. If the gauges do respond to this test, I'd suspect bad senders or (more likely) bad connection where the wire plugs to the sender. Be sure to clean these connections really well before plugging them back together.

 

If the gauges don't respond to the grounding test, check at your fuse panel to make sure you have power. Put a test light on each side of the metal clip that holds the fuses, not the metal end of the fuse. Then you know for sure there isn't corrosion between the fuse end and the clip. I'm not sure which fuse is for the gauges but it is easy to just check them all (with the key in On position).

 

Or if your amp and oil warning lights come on with the key in On position, I think that indicates you have power to the same circuit that powers the gauges (that is how it looks on the wiring diagram anyway).

 

If you end up removing the regulator can from the panel, use a test light or meter to be certain you have power to where the regulator plugs in. A broken printed circuit board or bad connection at the multi-pin connector from the harness to the board is always possible.

 

If your can style regulator is like the built-in style the later 510s use, you should have continuity across the two posts on the regulator when it is not powered. If you don't have continuity I'd guess the regulator is bad. If new ones are no longer available from Nissan then start reading the info in one of the above links to installing a modern solid state regulator.

 

Len

 

 

 

 

[hang_510]

I have a cluster with just the fuel \ temp sender left.

Its yours for a couple bucks plus shipping.

[Sastis]

190

190

180

210

 

Compression test, warm. No leak down test

[Sastis]

Now to clean the point of the tachometer. Beside the point is there anything else I could possibly clean?

[LenRobertson]

Now to clean the point of the tachometer. Beside the point is there anything else I could possibly clean?

When put the fuel/temp gauge cluster back into the main instrument panel, I was concerned about the copper contacts where the two circuit boards come together. Mine looked slightly dull and tarnished so I cleaned the surfaces on both boards with a fiberglass eraser. Back in the days of film cameras it was recommended to clean battery contacts with a clean pencil eraser so that might work well. Or maybe a clean, fine Scotchbright pad. I'd be careful not to use anything like sandpaper that leaves a rough surface as that may keep the surfaces from contacting each other really well. And it may not be necessary anyway although when I had everything back together the gauges worked for a couple of days, then quit. I remove the panel and re-tightened the three screws that hold the fuel/temp cluster to the main board. It has been working great since.

 

Len

[Sastis]

Clean the contact point the copper and still same wtf.....

[LenRobertson]

Clean the contact point the copper and still same wtf.....

I'm developing a theory (which may not be correct so I welcome any criticism/ideas) that after 40+ years these voltage regulators get out of adjustment enough that they just don't work anymore (due to burned points or aging of the bi-metalic strip or who knows what) . Given how tiny the components are I wonder if they are fixable? I thought maybe just sandpapering the points might bring them back to life but I was studying the regulator on my spare gauge cluster and noticed the shaft that makes up one of the points is threaded. My guess is this was for a bench adjustment originally done at the factory. Whether the points can be re-adjusted to work again seems dubious considering the small size of the flats on the threaded shaft. If a tool could be made to turn the shaft then adjusting seems it would be much trial and error. But if someone want to try adjusting the points and makes it work I would love to hear it is possible.

 

I added another pic to my Dropbox folder (DSC02323) that shows the threads on one side of the points (above the green wire, threaded through the square copper colored piece).

 

It may be converting to a solid state regulator is quicker and easier than trying to fix the original. Or going to after market gauges but that will be a lot more money that adding a solid state regulator.

 

Len

[Lozer]

One quick question. Do your reverse lights work?

[LenRobertson]

One quick question. Do your reverse lights work?

I don't know if your question is aimed at me but I'll answer anyway, cause why not? I know my reverse lights don't work because when I converted from auto tranny to 5-speed, I didn't hook the reverse light wires to the switch on the new tranny. I don't recall if there was some difference in the wire ends or (more likely) I was so excited to have the 510 running again that I never bothered crawling back under to hook up the wires.

I think the reverse light circuit is fairly simple. Check for power going into the switch on the tranny and power out when the shifter is in reverse. Or a continuity test through the switch when in reverse. Take the reverse light bulbs out in the trunk and use a test light to see if there is power to the stud down inside the socket.  Be sure the inside of the socket and outside of the bulb are fairly clean and corrosion-free.

 

Len

[datzenmike]

If you are suggesting that a blown fuse is the problem..... reverse lamps, oil and charge lights, and turn signals are all on the same fuse. I believe.

[Lozer]

I ask because I just went through this on my 71. Fuel and temp would spike but sometimes work. Drove me frigging nuts and i'm a jaguar trained auto tech (master of shitty wire). I found that the reverse light loom was shorting to the chassis causing the entire issue. Sooooo it's worth a look. Also it should be noted it would not blow the fuse.

[Sastis]

Well there are a bunch of wire hanging underneath the car where my tranny is. Did I tell you I ran something over which maybe be the problem? I'll check the wires underneath the 510. Should I also check the wire harness and rear lights. I'll see if my reverse light work tonight.

[Sastis]

Well my reverse lights work now but did not solved the problem.

[Lozer]

KK so you got my curiosity going. Theres only 1 yellow wire going from the gauge pod plug back to the sending unit.  ohm the wire to see if its got a short in it.