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Unread 04-23-2013, 07:31 PM   #1
Rollbar
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How many Watts does a Jeep CJ7 ('84) Produce ?

from it's electrical system ?

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Unread 04-23-2013, 07:39 PM   #2
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Originally Posted by Rollbar View Post
from it's electrical system ?


You would need to measure the amperage and voltage to figure it out. Assuming you have a 12 volt sustem and a 100 amp alternator it'll be putting out approximately 1200 watts. that is in a perfect world however.

Voltage x Amps = Watts
12 X 100 = 1200
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Unread 04-23-2013, 07:43 PM   #3
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Thanks, I was thinking that but wasn't sure. I'm looking for a potentiometer to install for the fuel gauge (SWarner) and the guy at radio shack need to know the wattage that the potentiometer meter needed to be. Still looking for their part number for the potentiometer.

Thanks,
Jim
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Unread 04-23-2013, 08:24 PM   #4
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Originally Posted by Rollbar View Post
Thanks, I was thinking that but wasn't sure. I'm looking for a potentiometer to install for the fuel gauge (SWarner) and the guy at radio shack need to know the wattage that the potentiometer meter needed to be. Still looking for their part number for the potentiometer.

Thanks,
Jim
nevermind I just actually read your post haha... that usually helps.

How are you wiring this thing up? Like the stock one is with a floater but with the floater attached to the potentiometer? doesn't really matter I'm just curious
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Unread 04-23-2013, 08:44 PM   #5
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Originally Posted by Rollbar View Post
Thanks, I was thinking that but wasn't sure. I'm looking for a potentiometer to install for the fuel gauge (SWarner) and the guy at radio shack need to know the wattage that the potentiometer meter needed to be. Still looking for their part number for the potentiometer.

Thanks,
Jim
Pots that drive gages more often work as voltage dividers - and therefore have sod-all to do with overall system capacity.

There are a few options for alternator for your year (I'd need to know more,) but it's irrelephant given the problem. The potentiometer/voltage divider is on the fuel sensor/pickup stinger in the fuel tank, the gage should be calibrated to work with that sensor range (two data are important - the resistance range of the sensor and the operational direction: such as 0-90ohms, 0ohms at full, 90ohms at empty,) and that doesn't care if you even HAVE an alternator.

Methinks the guy was talking through his hat...
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Unread 04-23-2013, 09:16 PM   #6
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The S-Warner gauge is for the CJ 10/73 ohm sender (new). We know the aftermarket senders are junk at best (new) and at full tank the new sender is reading 23ohms at the pink wire. When the gauge is hooked up, the gauge reads Full-this I was looking into a potentiometer to calibrate the gauge and leave it hooked up. When I fill up, dial it in and I should be good IS MY THINKING, however that goes.

Tested outside the tank was pretty close at best.

Thanks,
Jim
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Unread 04-23-2013, 09:17 PM   #7
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nevermind I just actually read your post haha... that usually helps.

How are you wiring this thing up? Like the stock one is with a floater but with the floater attached to the potentiometer? doesn't really matter I'm just curious
I think it needs to be from the "S" terminal to ground to dial in the gauge.

Or I could just attach a 73ohm resistor from the "S" terminal to ground and it should work but i would rather dial it in, I think
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Unread 04-23-2013, 09:44 PM   #8
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Whatever you do, don't go over 1.21 jigawatts...
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Unread 04-23-2013, 09:49 PM   #9
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Whatever you do, don't go over 1.21 jigawatts...

That could be very bad-could end up in the 1600's


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Unread 04-24-2013, 02:52 AM   #10
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Quote:
Originally Posted by Rollbar View Post
The S-Warner gauge is for the CJ 10/73 ohm sender (new). We know the aftermarket senders are junk at best (new) and at full tank the new sender is reading 23ohms at the pink wire. When the gauge is hooked up, the gauge reads Full-this I was looking into a potentiometer to calibrate the gauge and leave it hooked up. When I fill up, dial it in and I should be good IS MY THINKING, however that goes.

Tested outside the tank was pretty close at best.

Thanks,
Jim

IF I read this right,

First problem is that the fuel sending unit is reading 23 ohms when the tank is full.

This could be because of several things.

1. The stop limit arms are not adjusted causing the float arm to stop before reaching full swing. You need to adjust the stops so that the float arms can travel the whole distance in the tank.

2. The float can have a crack filling with fuel causing it to float lower than it should when the tank is full.

3. The wiper arm on the sending unit was not adjusted properly and not moving the whole distance when the arm is at the end of it's travel. Surprisingly this can be adjusted.

4. The float arm is bent wrong not reaching the end of the travel when full.

Second problem is that the gauge is reading full even though the sending unit is at 23 Ohms.

First you should make sure the gauge is working. Get some 1 watt fixed ohm resistors and check out the gauge. Usually when the fuel gauge reads full when the tank is not full is because the internal regulator has stopped working usually because of a bad ground.


Say you get the fuel gauge working properly, if you put the poteniometer in parallel with the sending unit to make sure the resistance goes to 10 ohms then the gauge will be OK at ful but the rest of the range will be off.

23 Ohms + 23 Ohm in || will give 11.5 Ohms OK for full
But....
23 Ohms + 76 Ohms in || wil give you only 17.657. So you can be running out of gas and the gauge shows 3/4 tank.

You can't put a pot in Series and hope to drop the the resistance below 23 Ohms.
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Unread 04-24-2013, 06:20 AM   #11
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Quote:
Originally Posted by 5-90 View Post
Pots that drive gages more often work as voltage dividers - and therefore have sod-all to do with overall system capacity.

There are a few options for alternator for your year (I'd need to know more,) but it's irrelephant given the problem. The potentiometer/voltage divider is on the fuel sensor/pickup stinger in the fuel tank, the gage should be calibrated to work with that sensor range (two data are important - the resistance range of the sensor and the operational direction: such as 0-90ohms, 0ohms at full, 90ohms at empty,) and that doesn't care if you even HAVE an alternator.

Methinks the guy was talking through his hat...
well at first I didn't know what he was trying to do so it was a much more simple problem to figure out.

I'm no expert electrician, I'm a jack of many trades and an expert at none.
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Unread 04-24-2013, 09:46 AM   #12
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The sending units arm did swing all the way as did the wiper arm. That's what I'm confused about.

Do you are saying if I install a pot then it will be off except for Full=no good. As I mentioned in a pm, can I add the 73 ohm from "S" to ground so I will get a Empty reading or is that the same as the pot?

Question-is there a aftermarket sender that is not junk that will work ?

Thanks,
Jim

P.S. I'm about to cut a hole in the floor so I son't have to keep dropping the tank
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Unread 04-24-2013, 09:57 AM   #13
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It would be easier to recalibrate the fuel gauge to work with the sending unit.
There are adjustments for Zero and Full Scale but I don't know the range of adjustment available.

First you have to make sure the Gauge is working...
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Unread 04-24-2013, 10:02 AM   #14
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Just Read your PM. That changes everything.
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Unread 04-24-2013, 10:02 AM   #15
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New gauge SW.
Going to read PM.

Thank you John.
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