Erratic Fuel Gage

[blacksheep4]

I have a 1998 Dodge Dakota and have a question about the automatic Fuel Gauge. It is very sparatic once it is completely filled. I can put a full tank in, reset the gauge and when I get not even a mile down the road it will read 10 gallons less than what it was when I filled up. It doesn't just do this when I fill up either. It does it constantly when I am driving. The funny thing is, when I park it will read right around the number when I fill up. But when I start it up again it will read a compelety different number than it did before. When it reads like this it is on the distance till empty setting and the actual gauge itself. If you know what this might be or know or have had the same problem please let me know because it is driving me crazy.

[NAJ]

You will need an OBD2 compatable scan tool and I do not know if aftermarket scanners will access Compass/Mini Trip.
First you have to determine if there are any PCM faults as this may affect the way the Compass/Mini Trip Computer reads.
Is it only the trip computer that reads erratically or the gauge also?
If the gauge is also reading erratically start by replacing the sending unit.Sending unit was a big problem on all Jeep models from that time period,the Dakota is probably the same setup.You can purchase the redisigned sending unit at any dealer.
If it is only the trip computer and there are no PCM or Body codes and the trip computer fails the self test Chrysler says replace the trip computer.
Again you will need a scanner(Chrysler DRB3)to run all appropriate diagnostics.