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#1
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testing a fuel gauge?
Before I order a new sending unit how do I test my fuel gauge? The book mentions a special tool. Basically the gauge reads empty all the time. The wireing from the gauge to the sending unit is good and the sending unit has a good ground too.
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#2
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Simply unplug the wire from the sending unit and ground it. The fuel gauge will peg full. If it does not peg full it's the gauge or wires in between. If it pegs it's the unit. Also pull the unit and make sure it works out of the tank before you order one. Some times all you need is a float. Make sure to get a new sock if you order a new sender.
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#3
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I agree, check the float. I bet it's full of gas and setting on the bottom of the tank.
I know where you can get on if you need it. Tom |
#4
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I always thought grounding the wire made it read empty? I'll have to check it tomorrow. My bet is on the sending unit. I see year one has them for like 50 bucks
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#5
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Grounding the wire to the gauge will make it read FULL. Test the sender before you buy a new one.
I use a test light and a ground wire. Ground the sender and then run a test light between the positive of your battery and connect where the wire attaches. As you move the float arm up to simulate a full tank the light will get brighter. As you lower it the light dims. Remove the float and drop it in a coffe can of gas. If it sinks that's your problem. Most of the old floats are bad I've discovered. I think year one gets like $150 for a sender. You can get reproductions from the Paddock for like $100.00 plus shipping. I just went through this and all I needed was a brass float. Make sure the ground strap is connected to the pipe of the sender. You might try grounding it with a test wire just to make sure you have ground before you go to the trouble of removing the sender. Tom |
#6
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And floats are much cheaper too.
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#7
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Well suddenly I have a new problem. Got the new ehater core in and fire the 340 up... hmm no oil pressure? No just every gauge minus the ammeter doesn't work. So I'm thinking voltage limiter and hopeing no cooked gauges. So does anyone know if they make repro voltage limiters for a rallye dash?
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#8
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Ive seen them before. I think year one had them. Not sure, but call and check them.
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#9
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I usually end up answering my own questions after I look into it some more. Whoever was in the dash last decided to hook the voltage limiter which looks like a condeser up to the wrong peg in the back. It was hooked to my gas gauge. Hooked it up right and now everything minus the fuel gauge works. Getting better. If it stops rainign I am going to see if grounding the fuel line helps. Its missing the ground strap.
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#10
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dead guages......................
i am having the same kind of problem with my 68 coronet.
speedo works, amp guage works, but temp and fuel are dead!! sending unit grounded out fine on the fuel, temp gauge checked out fine. the guy i bought the car from a few months back says after they put the dash back together, they didn't work. they were fine before re installing the dash. i was told to check the little voltage regulator. i know what it looks like and where it is located, but............. WHAT DO I HAVE TO DO AND HOW MUCH DO I HAVE TO TEAR DOWN TO GET TO IT? is it going to be that bad of a job? also looking for a rt 150 mph speedo, not the round rally type like in a bee or charger but one that looks like the straight line 120 mph on stock coronet 440's. where can i find these? |
#11
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wanabee-
If I read correctly, when you ground out the fuel sender lead and the temp lead, both gauges move to the limits. If that is the case, then the dash voltage regualtor is not the cause. The rectangular dash voltage regulator can be reached with teh dash still in place. Just laydown on the floor and reach up behind the dash. It is on the side of the dash closest to the door. It is just plugged in. You can either replace the regulator or make a solid state regualtor to go in place. 76duster- The dash voltage regulator is a rectangular unit. What you moved was a capacitor (very much like a condensor). |
#12
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more on voltage regulator
FWIW....While looking for a speedo for my 87 D 150, I got a dash out of an 89 Dodge pickup at the junkyard today and it has the same voltage regulator as my 75 Dart Sport. Lamp holders were the same, too.
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#13
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gauges............
EHOSTLER:
how do i make a solid state v-reg? |
#14
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Resurrecting this post
Compared resistance on both old and new sending units. Full was about 9.5 ohms and empty was 76. Not too far off what was posted above. New one was purchased because old one was suspected as reason for gauge not working. Hmmmmm
Installed the new one and it does the same as the old one - with key on, the needle barely reaches the empty mark. Using the gauge checking methods posted earlier, found that grounding the gauge wire pegs the needle to full as described. Placed test light in line to terminal on sending unit. When key is turned on, tester lights up for about 3 seconds and goes out, and needle does not move on gauge. What am I looking at here, a problem with the gauge, or maybe the voltage limiter? Although, the temp gauge appears to be functioning properly. |
#15
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Is the tank properly grounded by the clip-on ground strap between the fuel line and the tank sender?
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#16
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Yes, in fact, I added an additional ground with alligator clips.
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#17
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If the gauge goes to full when the wire is grounded, the gauge and the IVR are working OK.
Instead of checking the sender resistance with an ohm meter, try hooking the sender up to the sender wire outside the tank (be sure the sender is well grounded) and manipulate the float arm through its entire range while somebody inside the car observes the gauge action. Even though the resistance looks good with an ohm meter, a faulty sender might not work correctly with actual current flowing through it. There seems to be a lot of problems with the current crop of repop senders. |
#18
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You could also use a potentiometer (variable resistor, such as a dash light dimming switch) hooked to the wire to the sender. Changing the resistance should move the gauge indication through its range. That way you don't have to pull the sending unit to test.
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