Mechanical/electric fuel pump question

[XJChad]

Ok. I had noticed there is a difference btwn these two. The 89 has what looks like a micro-board, where the '82 just has a metal box near the top where the wires and float arm go in to it.

I did notice when I put fuel in the tank with the 89 sender the gauge needle came up about a needles width over empty. I put 5 more gallons in and it didn't come up any further.
*note, I didnt test either one with a meter either.
I will pull the unit back out and tinker with the float arm like you recommend and see if the gauge changes.

[carnuck]

read my footer

[Tatsadasayago]

It would be enlightening to know what exactly causes the AMC gauge funkyness.
There is a mysterious paper wrapped noise suppressor on the backside of the cluster circuit board I've often suspected. It appears to be a steel bar with enameled copper wire wrapped around it. In the radio world we call them RF Chokes and I assume the same principle applies here. It has a 125 on it and I assume that is an inductance rating.
Now the dash circuit shows DC power coming into the cluster from the ignition switch through the suppressor and hits the temp gauge first while sending DC to the other gauges in series. It looks like the metal bar inside the suppressor is grounded. Now should the enamel on the coil windings crack and flake off as tends to happen with old coils, it's possible a small short to ground might start and grow as time goes by--acting as a resistor--and causing a voltage drop at the gauges.
As far as the Oil, temp and fuel gauges go, lower supply voltage would equate to a lower gauge reading in the same manner as increased resistance does at the sending unit.

At least that's my theory anyway.




Perhaps our resident electrical guru already knows the cause or if not, might share his opinion on this.

[XJChad]

Carnuck, Im not following what you are meaning, "footer"?

Today it went to a quarter tank and at one point while stopped, up to 1/2 a tank, later dropping back to a 1/4. It has stayed at just under a 1/4 so tomorrow I will probably stop and get gas and see what happens.

[serehill]

Actually he wants you to read the final statement in Yellow in his Signature.

[XJChad]

Actually he wants you to read the final statement in Yellow in his Signature.

I figured he was talking about his signature, but I cant't see it. I went to his profile and still can't see it, but I'm on my phone. I'll have to get on a computer later and take a look.

[carnuck]

Full Size Jeep gauges are for amusement only. Any correlation between them and reality is purely coincidental!

There. Not in yellow now

[XJChad]

Full Size Jeep gauges are for amusement only. Any correlation between them and reality is purely coincidental!

There. Not in yellow now

LoL right on. Im gathering that. This thing has gone from being on "E" to showing 1/4 to 1/2, then back to "E". This was after driving about 10 miles and adding another 10 gal of gas.
Oh well, I'll figure it off of mileage eventually.

[carnuck]

If it doesn't leak, I fill it up, drive a set safe distance (like 100 miles) and fill again. Do that several times and you will get an idea how far you can go on a tank. I drove my J4000 10 years without a gauge and only ran out when some &*$%^%$@( siphoned my tank.

[XJChad]

Ok. I have yet to fill it all the way just because I didn't want to mess with a full tank if I had to drop it again. I think I'm good to go other than the gauge issue.

It seems to be running fine so far. I'm sure the carb could stand to be cleaned out, but its running fine, so no need to push my luck!!

[rlars7]

If it doesn't leak, I fill it up, drive a set safe distance (like 100 miles) and fill again. Do that several times and you will get an idea how far you can go on a tank. I drove my J4000 10 years without a gauge and only ran out when some &*$%^%$@( siphoned my tank.

Second this. I use to have a pad of paper in my J10 and would write down milage on fill ups. Got pretty good at estimating when I was at 1/4 tank and needed to fill up.

-Rob

[jaber]

I can get 150 miles out of a full tank in my J-20, then I start looking for a station. I also carry a 5 gal jerry can full, just in case my blond flairs up and I run out, it is enough to get me there...