It has been covered i'm sure, but I need to know were it is and what it looks like. The gage on my 90 Aerostar is going nuts. Thanks for any help I can get with this.

 

Fuel Level Indication System

The fuel level indication system is a magnetic gauge system. It consists of a magnetic fuel gauge (9280) mounted in the instrument cluster (10849) and a sending unit located in the fuel tank (9002) with an instrument cluster gauge amplifier (10E849) in series between the two. No instrument voltage regulator is used with this system.


Fuel Gauge

The magnetic gauge movement consists of three primary coils, one of which is wound at a 90-degree angle to the other two. The coils form a magnetic field which varies in direction according to the variable resistance of the sender unit which is connected between two of them. A primary magnet, to which a shaft and pointer are attached, rotates to align to this primary field, resulting in pointer position. The bobbin/coil assembly is pressed into a metal housing which has two holes for dial mounting. There is no adjustment, calibration or maintenance required for these gauges.


Instrument Cluster Gauge Amplifier/Check Gauge Module

The instrument cluster gauge amplifier electrically averages fuel sender readings so the fuel gauge displays actual fuel level and not fluctuations due to sloshing in fuel tank. The instrument cluster gauge amplifier is a small printed circuit board which latches into a pocket on the back of the instrument cluster. The electrical connections for ignition, ground, input from fuel sender and output to fuel gauge are made through a spring-type connector on the instrument cluster gauge amplifier to the instrument cluster printed circuit (10K843) on the instrument cluster. There are no provisions for calibration or adjustment of the instrument cluster gauge amplifier.




Fuel Sending Unit

The fuel sending unit consists of a variable screened resistor made up of a ceramic substrate. It is controlled by the action of an attached float in the fuel tank. When the fuel level is low, resistance in the sending unit is low. When the fuel level is high, the resistance in the sending unit is high. As the float moves from empty to full, the resistance will gradually and continuously increase.

see for picture of module>

http://home.comcast.net/~classical_m...D-2360807.html

 

Remove the gauge cluster. The anti-slosh module is a circuit board about 2 inches square attached to the main board.

I had mine out last month; should have made a photograph. I checked all the solder joints and cleaned the connentions but no joy. My gauge is still wonky. Next, I'll drop the tank to get at the sender.

 

I replaced the pump/sender in my '89 and the gauge was still funky.
I bought a new amplifier and they worked fine.
Then one day, for lack of a better thing to do, I took the new one out and put the old one back in and it worked perfectly from then on.

No, I have no idea why.

 

corrosion on spring contacts amplifier/instrument panel circuit board, common in high humidy areas and vehicles parts within a few miles of chemical processing plants. Paper mills are infamous for causing corrosion to vehicle electrical systems

 

Thanks guys, I will pull the dash and take a look. I put in a new pump about 2 years ago, and it started going wonkers not to long after. I did not know until after the fact that you can get a pump without a sending unit, but you can not get a sending unit without the pump.