gauge problems

[lxrubin]

Most importantly is the gas gauge which just shows FULL all the time. The rest of the gauges work fine. It was showing near empty at one point when I just acquired the car before running out of gas. It was filled up a little, and the needle moved slightly, so it was definitely working then. It was in the shop for exhaust work recently and they put $20 in it to drive it in and out of the garage and since then its showing FULL all the time. I have to fill it up almost every time I drive it to make sure it doesn't run out.

Another issue is with the speedo and tach. Both are slightly off. Do the sensors wear out and give innacurate readings? where are these sensors located? is the speedo a gear driven piece off the transmission?

The car is a 74 cuda with a 360 and a 727

[aarracer]

I'd check the gauge wire for a burnt through ground fault (grounding the gauge wire will/may give a full tank signal), and the fuel line ground jumper (the connecter between the sending unit and the fuel line that jumps the rubber line between the two) for being loose.

[chirorod]

I second the motion about being grounded before the sending unit. also, could be bad gauge. if you can, disconnect the lead to the tank. should then read empty. if not, bad gauge. also, there may be a voltage limiter for the gauges, which may be bad. also, the sending unit may be at fault. changing it means dropping the tank, which should be done with tank almost empty. just had to put my 2 cents in, which buys about half a percent of a gallon of the gas you might have to use up before dropping the tank.
chirorod

[ehostler]

I doubt that the problem is with the IVR. When those fail, the guage will normally go to E. Disconnect the wire from the sender (float stuck at the top of travel) , if it goes to E, then the problem is a faulty sender. If it stays at F, then you need to trace the wire.

For the tach and speedo, there are no sensors. This is a 34 year old car. The factory tach is tired. If you want to use it, you will need to remove it from the instrument cluster and send it out to be calibrated.

The speedo uses the pinion gear in the side of the tranny. If the speedo is off, you need to get the correct gear and replace it.

[dodger1]

The fuel and temp gauges share one voltage reducer. If one or the other works, the voltage reducer is OK. Sounds like a ground fault or just a bad sender or gauge. Have fun

[lxrubin]

Thanks guys, I'll check the wiring this weekend and let you all know what the problem is

[adodgemann]

Speedo could also be a dry-sticky drive cable. This most likely cause the speedo needle to jump or bounce........

[cudabob496]

http://www.madelectrical.com/electri...p-gauges.shtml

[cudabob496]

http://www.cuda-challenger.com/cc/in...?topic=34673.0

[Monaco Man 78]

my guage is completely opposite, it will slowly move to the front of the E and stay there, then sometimes it will show how much gas i have in then sometimes it will show a half tank when i just completely filled the tank, already dropped the tank took the sending unit out, check it with a multimeter, it was working properly, the brass float had a little liquid sloshin around (gasoline) i think that is the cause the float, i had a fried neutral safety wire all the way to the fuse box, fixed that problem. check for ground breaks couldn't find anything put a 12 volt tester to the guage registered around half and very very slowly going to full, tested again, went to full mark at normal speed, every other guage is working properly, dont know, more than likely the float, anybody know a part number for a brass float and where to get it, any suggestion that i use to fix this problem would really help me out, its killing me to carry around a gas can in my trunk, i have a 1978 Dodge monaco, cant find another sending unit they dont make one only for early b body models, any suggestions where to find another sending unit too, ive check everywhere here salvage yards, partstore online nothing whatsoever, anybody help please. also i have a 25.5 gallon tank, ground for the sending unit is grounded to the chasis via wire,with a black terminal connecter, not a ground strap like early b body's.

[chirorod]

MonacoMan78
It seems to me that you've found the problem. The float shouldn't have any gas or any kind of liquid in it. One thing you can do while tank is out. Use jumper wires to hook up sending unit wire and ground, turn on ignition move float arm to full position and check gauge reading. If gauge reads full, that confirms that this is a float problem. If that doesn't work, use the ohmmeter on your multimeter to check continuity of the sending unit wire to gauge. Should have close to zero ohms. I don't know where you can find a float or sending unit. I looked it up in a couple of places and drew a blank. You might just check on floats from other mopars. Sending units will be different, but floats might be close enough. All it has to do is float and fasten to float arm.

[chirorod]

MonacoMan78
check autoelectricplus's post under parts for sale.

[Monaco Man 78]

thanks for the help

[75mopar]

monaco man, go straight to a chrysler/dodge dealership, and ask the parts department! Im sure they will have one.

Ive got a 73 chrysler newport, gas gauge was working fine then one day just went straight down to E and never back up. Pulled the wire grounded it exc exc exc, gauge checked out good, so did the wire, leading to the sending unit being bad.

I went to every damn parts store.. nothing. I have a buddy that works at a local chrysler dealership and his parts man came up with it. Only chrysler makes the part, and there the only ones that do. a bit pricy though around $160, and thats my price, dont know what it is regular msrp.

hope this helps good luck!

[wmfd7]

year one has the brass float, around or less than 15 bucks.