Club Cobra - electronic smith oil pressure gauge

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electronic smith oil pressure gauge

Here is the issue:
I have a brand new electronic Smith oil pressure gauge I got from nissonger.
I wired it up exactly per instructions, This is a new motor build so there is no oil in the block it is just a mock up at this point.

When I turn on the key the gauge goes to 95 PSI and stays there. I tripple checked the wiring ( hot, ground, sender input) it is all good.

I called nissonger and he told me that it could be a grounding issue to the sender, this makes no sense to me because the gauge has a ground wire running to the sender, so I also grounded the sender to the chassis ground, same issue. Same result if I disconnect the sender, so to me this rules out the sender.

I had him send me a new gauge, same thing. So I turned on the key and applied an air compressor to the gauge to see if I get a reading, when I do this the gauge goes to 100psi then back to 95 PSI... Is this normal? I need advise on this.

I assume you are using the the Smiths pressure sender and not the Autometer sender that came with your factory gauges?
https://www.petrolheadheaven.com.au/...ra-gauges.aspx

If so there should be only one wire going to the sender and its not a floating ground type so needs no strapping to ground. The NPT fitting should handle that (unless you have a lot of Teflon tape on it, actually you shouldn't use any).
I'd start by using a meter on the SMITHS sender and reading the OHMs from the spade connector to case. It should read one of the range specs for your particular sender. EX: 33 ohm engine off, 240 ohm full sweep. (Those are VDO numbers I'm throwing out)
Also disconnecting the the sender the gauge should peg at full sweep.

My gauge has a ground wire from the gauge that I grounded to a nearby chassis bolt.

Quote:

Originally Posted by spdbrake (Post 1470786)

I am using the sender nissonger sent me, it is a variohmEPT2100
https://www.variohm.com/contentfiles...sor_1907_O.pdf

It looks as if it puts out a voltage of 0.1-5v

the sender is ouputting 2VDC with 0 oil pressure. This is a concern because I am putting in a BRAND NEW MOTOR and the oil pressure gauge MUST work...

what is driving me nuts is:
when I turn on the key it goes to 95PSI and stays there( it seems to gidder a little like it is sensing 95PSI of pressure) When I disconnect the sender it goes full sweep 100PSI, When I put an air compressor on it it jumps tp 100PSI and then back to 95PSI. Please note that the sender is NOT connected to the motor, but I did make sure the case is grounged to chassis ground. The gauge has 3 wires 1) ground 2) key hot) 3 sender output. why is it sitting at 95psi when key on? is this normal because there is no oil ? no clue

Smiths Electronic Gauges

Mike:

Here is a wiring diagram for Smiths electronic gauges. My oil pressure gauge works fine. The sender I have is the one listed by speedbrake above.

There are four wires coming out of the gauge:

Black - to chassis ground
Red - to the instrument light rheostat, for the light
Green - switched power (+12V)
White/Blue Stripe - to the sender

The sender has no ground, as it grounds through the threads. Be sure the sealant is not electrically insulating.

The gauges sweep through their motion when the key is turned on, then sweep back to zero. I don't have my car, so I can't do any tests or measurements for you at the moment.

Good luck.

Wow, The transducer they sold you has a variable voltage output.

The gauge is looking for variable OHMs input.

The Smith Sender PN PTR1000-6-10 shown on all the sites I can find says it works with the Smiths Oil press gauge PN APG1310-02C.

The Smiths sender Ohm range is 300-10 ohms.
https://www.smiths-instruments.co.uk...re-transducers

I'd contact Nissonger and request an explanation on how the gauge is going to covert the voltage to a usable reading. I may be missing something totally here but it doesn't feel like it. Whats also weird is the Nissonger site lists the PTR1000-6-10 sender.

I must admit the transducer is working since you do have a gauge scale reading, its just off quite a bit. So either the transducer is faulty or they sent you the wrong one I'm guessing.

Quote:

Originally Posted by spdbrake (Post 1470804)

on smiths web site it says this
"We also have an electronic version that is identical PG1310-00CB, that will work with a motorsport sender PTTR2300-10-8NKIT"

this is the gauge I have. PG1310-37CB I am thinking the sender is bad as it is putting out 2vdc with 0 oil pressure.

I think you're correct on sender being T.U. then.