Autometer gauges and tach head scratch

[Dale M.]

[1950split]

Ok, so I did a test with an other appropriate autometer sender.

I had the same result than with the first one. The needle pegs out.

I have also tried to wire the pressure gauge only directly to the "out" side of the fuse box and grounded it on its own. Again the needle pegged out.

What I also noticed, I don't know if it tells anything, that with the sender wired to the gauge, the + wired but not the -, the gauge pegs. I would have thought that without grouding the gauge the needle would not move?!?

I have a vdo pressure gauge and sender. As I had a few minutes I decided to test this set and wired it exactly the same way as the autometer gauge and the needle did not peg out.

So I guess the brand new but stored for a few years autometer is the culprit

[MacLeod Willy]

Do you have 1 or 2 terminals on the sending unit?

[1950split]

The Autometer pressure gauge has 1 terminal.

[Dale M.]

On your A-M pressure gauge, if you ground "sensor" terminal does it still go full scale...

Dale
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.

"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[1950split]

Dale, do you mean to ground the sender at the connector to which the sender/gauge wire is connected while the sender is wired to the gauge?

[SBD]

[Dale M.]

Yes ground sender terminal either at gauge or at end of wire.... It should not go full scale but stay at lowest pressure position on scale...

Grounding sender terminal at gauge verify's gauge is working if it does not go full scale, then if you do it at connector at sender (wire) and you get different reaction check grounds and wiring...

IF you ground sender terminal and it still goes full scale, gauge it self is the problem (providing you have 12 volts and ground hooked to gauge correctly)....

Always have proper 12 volts (+) and ground (-) connected at gauge not doing do just confuses the issue by adding false values and conclusions to the mix and you will just be more confused...

Only test for a pressure gauge is at sender terminal and if its not grounded you get full scale (full right needle), if it is grounded you will get no gauge movement (full left needle) ...

Dale
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.

"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[Howard 111]

They count on you drilling a hole through the metal dash, and that grounds the gauge, but that's not always the case. Ground the gauges.
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[MacLeod Willy]

Does your hookup look like this.
It also tells why the needle will peg on power up
http://www.autometer.com/resources/index/faq_view/id/5

[1950split]

Ok, got it.

I grounded the sender terminal and the needle pegged.

This is confirmed by the test I did with the vdo gauge which connected the same way did not peg.

I am quite surprised that a brand new gauge comes broken

[1950split]

Small update on my test bench.

I got another set of autometer oil temp and pressure gauge, wired them the same way and hurra, they work!

The tach does not work yet. When the engine idles, the needle jumps all around. What is surprising is that I took it out of my bug recently to replace it with a smaller one and it was working perfectly.

I have the blue wire cut and brown intact at the back. Don't see why if used in the bench this set-up would change..

[KTPhil]

Did you use Teflon tape on the threads of the sensors? That may create high or infinite resistance in that circuit.

[1950split]

Thanks for your reply but the issued with the oil pressure and temperature gauges is solved.

The issue now is the bouncing tach needle

[Aerindel]

Try the diode solution. I had the same problem with a VDO tach, a $2 diode solved it.
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Homemade woods/street, bug out rail. IRS, Balljoint front end. 1967 1600cc DP, Weber 32/36 progressive, tri-mil quiet pack. Rear only cutting brakes.

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