2 stupid gauge questions...

davmacdon

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Aug 23, 2003

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Dec 3, 2004

#1

• Dec 3, 2004

• #1

I just installed 2 Autometer Cobalt gauges. One is a fuel pressure gauge and the other is a vac/boost gauge.

My first problem is, where can I wire the power for the gauges so it does not turn off when the car is starting. What is happening is the vac/boost gauge is zeroing out when you turn the key on. As you turn the key to the start position, power is cut off to the gauge and other things like the radio while the car is starting. When power comes back on to the gauge, the car is going and the gauge tries to zero out with vacum and it is out of calibration.

What fuse can I use that power is not cut off while you start the car?

The other question is... Where is the best place to tap power so the gauge lights work when headlights are on.

Thanks for any help,
Dave

 

hllon4whls

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Dec 3, 2004

#2

• Dec 3, 2004

• #2

That is a function of the ignition key. It is not broken, just works that way.

Possibly get some power from the ECU, but that can be dangerous.

 

squeeeg

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Dec 3, 2004

#3

• Dec 3, 2004

• #3

You can run an all time hot wire and fuse it sererately then the fuse box. That way the ignititon has nothing to do with it. Just put it on a switch somewhere.

 

J

jerry beach

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May 20, 2002

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Dec 3, 2004

#4

• Dec 3, 2004

• #4

I would check into stealing some power from the cig lighter. Its hot all the time too. EDIT, if you tap this the guage will have power all the time. Maybe the positive side of the coil would be good, it has power in start and run only. I am not so sure thats a good plan, someone help me out here.

Tap your guage lights into the parking light circuit and they will always come on with them. Or replace the headlight switch so you still have the dimmer function. Thats what I would do. I have to fool with mine a bit to get them on if I have cut the top light, otherwise they stay on all the time. You will need to test that switch with a test light to know for sure its bad before you change it, but its common for it to go out.

 

HISSIN50

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Nov 29, 1999

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Dec 4, 2004

#5

• Dec 4, 2004

• #5

many cars have the cut-off feature - it can be accomplished with an additional SPDT relay, if desiring the feature. sounds like you need to ditch it (BTW, how do you have an electric vacuum gauge. i have never seen one).

but to get around the cut off (it helps to give all available power to the starter during cranking), i dont know what circuits, if any, dont use that interlock/cut off feature (you dont see "Jrichker" or "TMoss" at the top of this post, do you. ).

worst case, you could run a hot at all times wire and a toggle switch. i bet if one tapped power for the gauges from the [yellow] ignition wires under the column, those would work (or something else that is in the actual ignition circuit - it should have constant key-on power. if it shut off like the radio, umm, the car would have a hard time starting. LOL).

wow, that was a whole post of nothing. how about putting a test light on each key-on hot fuse and starting the car. note if the light goes out while in crank position.

good luck.

 

shttygtstang

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Jun 2, 2004

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Dec 4, 2004

#6

• Dec 4, 2004

• #6

i have an autometr guage and the only lectic it has is for the light

 

HISSIN50

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#7

• Dec 4, 2004

• #7

shttygtstang said:

i have an autometr guage and the only lectic it has is for the light

Click to expand...

thanks for sharing.
you have a mechanical gauge.

 

shttygtstang

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Jun 2, 2004

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Dec 4, 2004

#8

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i kinda sound like i belong in a special home huh

 

HISSIN50

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#9

• Dec 4, 2004

• #9

shttygtstang said:

i kinda sound like i belong in a special home huh

Click to expand...

not at all - i was attempting humor in my above-post. im glad you took it that way.

it was just kind of a non-sequitor, as i read through the posts.

 

davmacdon

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Aug 23, 2003

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Dec 4, 2004

#10

• Dec 4, 2004

• #10

The test light thing that HISSIN50 suggests on each fuse might be the way to do it.

Both vac/boost and fuel pressure gauges are electric. The vac/boost gauge uses a map sensor(looks like a GM one) with a sample tube that you T into a vacum line. The fuel pressuge gauge has a sensor that connects to the Schreder valve.

I was going to do the junkyard twin turbo project with T3 Garret turbos, but there are so many clearance problems with the SN95 bodys compared to the FOX body it was not worth it. So it looks like Kenne Bell or Procharger time. I have those stock hyper pistons so I dont dare go above 5 PSI of boost(damn).

A guy I work with did the twin turbo thing on his 91' FOX and is about to turn them up to 15 PSI(goodbye block/bottom end) for a glory pass at the strip.

Below is a link to my gauges.

http://hp.autometer.com/products/cobalt/cobalt_instruments/cobalt_instruments.html

 

HISSIN50

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#11

• Dec 4, 2004

• #11

one more thing: if desiring a gauge that is actually on at all times, be sure to use an ammeter to determine how much draw there is from the gauge. i dont like to see total car off draw exceed .250mA (personal choice). just something to remember if deciding to hard wire the gauges to be on at all times.