Yesterday I was driving my 49 Dodge truck that has the complete, unmodified 96 Dakota chassis, wiring, and fuel system in it. The donor truck only had 44,000 miles, but the odometer now shows 66,000 miles.

Consider this a 96 Dakota.

The pump and gauge sending unit was replaced when the truck was assembled in 2022. its been working great until yesterday. The gauge was reading just over 1/2 full while I was driving around. I stopped and shut the truck off for about 15 minutes, and after the restart (and several more since) the gauge now reads empty. By the mileage its been getting and the miles on this tank of gas, a 1/2 tank would be pretty close, the tank is definitely not empty. The other gauges are all reading OK, so its not a fuse. As best as I can tell, the wires on the tank sending unit feel like the connection is still good. Getting to that fuel pump on this truck is a pain.

Actually removing the instrument cluster is easier, so it is out of the dash right now (I was hoping the plug on the instrument cluster was disconnected, but it was not).

With the cluster out, can I check the gauge itself? (I would need to know which wires on which plug). Should just need continuity across the wires to the gauge, and it would be a good or not good correct? OR I could power up the + wire and ground the sending unit wire for the gauge to read full, correct?

Can I check if the sending unit in the tank is functioning from the instrument cluster plug? My mind is telling me I can do that, but it is blank on the procedure, CRS is kicking in. I do have a multi meter.

What I found online, https://servicingmanuals.com/cars/dodge/dakota/



Testing

Thank you.

The very very short story about my lack of fuel gauge and fuel pump operation and thanks to your mention of possibility of corrosion at various connectors.
After installing my second new fuel pump that also did not run and in frustration jiggled the carp out of the fuel pump wire connector and it started working.
I then soaked the terminals in rust / corrosion remover and it has been good. Thinking about using some dialectic grease or something.
I got sidetracked because now the transmission does not work. ... To Be Continued.

Well, it looks like I get to drop the tank and pull the pump. i have about a 1/2 tank of gas to burn through before I drop the tank.

This one is my winter driver, so its best to do it soon, it sucks not having a fuel gauge through the winter. This sucks because that pump / gauge set up is only 3 years old and the pump works great.

At this point, I still can drive my coupe, but the extended antique plates expire for the winter on Nov 1st. Guess I know what I'm doing early next week.

on a very related note, my "bus" [99 caravan] acts sort of similar.
i can fill it, and the gauge registers full, but after a short drive, it shows empty.
i have replaced the fuel pump module, and it acts the same with the new one. there is a self test of the gauges able to be performed by pressing the odometer and trip buttons, and all the gauges passed this test.
i have checked the voltage and ground at the pump plug, and all appears correct there, the plug fits nice and tight, and there is no corrosion on any of the terminals.
i have also grounded the gauge feed wire, and it goes to full with the key on as it should.
i am beginning to think the problem lies in the harness from the tank, through the floor by the second row seats, and to the instrument cluster.
the fuel pump works as it should, and there are no drivability or fuel pressure issues.
as there are only three wires, pump 12v, ground, and gauge feed, it almost has to be in the gauge feed wire, or possibly the instrument cluster connector.
i also tried another cluster, and the fuel gauge acted the same while all the other instruments acted as they should.
at that time, i looked closely at the cluster connector plug, but did not see anything remotely close that would cause an issue with connectivity.
for now, [and for some time] i have been setting my trip odometer and fill up at around 200 miles, and it always takes around 7 gallons. but i only do short trips anymore except for doctor and hospital visits, and the occasional swap meet.
other "life events" keep me busy with little time to "play with cars"............
edit : one nice thing about the "bus", i can pull the fuel pump module without dropping the tank !

An update is required at this point.
In the beginning, after it first screwed up, I was under the truck and checked the connection at the fuel pump, (as good as I could on this truck). That connection felt like it was good. I checked the ground wire for the gauge. the ground is good.

I have all the ground wires ran separately, and all are attached to a specific bolt connected to the frame. I have had enough issues with vehicle grounds in my past, this is something I do with every vehicle I build. I will drill a new hole, grind a place on the frame (both sides) to clean metal, then I insert a new 1/4" x 1" long bolt with flat washers on both sides, and a lock washer with a nut. That bolt is tightened tight. Then all the ground wires in the area each get their own electrical eyelet, and the eyelets are put onto the threaded end of the bolt, with a flat washer on each side of the bunch of eyelets and the nut it tightened. The entire mess gets covered with grease to seal it. About every 5 years (unless a problem occurred before), it gets dissembled, the eyelets are inspected (and replaced as needed) and the bolt, washers, and nuts are all replaced on the freshly reground frame. This system has worked very well. I do one bolt under the hood, one under the dash, and one at the rear frame.

I pulled the instrument cluster out of the dash because it was easier then dropping the tank. Everything there checked OK. I pulled the dash apart Wed morning, got side tracked, then reassembled it yesterday afternoon, with the ignition off, the fuel gauge starts at midway between a 1/2 tank and a 1/4 tank, and as soon as the ignition switch is turned on, it does the 20 second drop to the empty line, where it stays (like it has been doing since the issue started last week).

This morning, the gauge did the same "empty" thing as it has been doing. I took the truck to get the oil changed at my buddies shop (old age has its advantages, and he does a great job looking the truck over). When I picked it up this afternoon, when I first started it, the gauge did its "empty" thing. Then, at about 1/2 the way home, the gauge started working. Its been working the last 3 times the truck has been started. It reads about midway between 1/2 a tank and a 1/4 tank. That is consistent with the miles on this tank of gas at the recent mpg range.

If it doesn't screw up between now and Monday morning, I don't think I'm going to pull the tank, though I may regret that in the middle of winter. We do keep track of the truck mileage, the number of gallons, the date, and the mpg, every time we put gas in the truck (always filled). The trip odometer broke last summer (as in broken gears in the trip odometer itself, it wouldn't always reset back to zero, then one day it didn't reset at all, reads 540 miles all the time).

We are having fun now.

As mom used to always say, "Well looky there, it fixed itself!" right up until it broke itself again.

Interesting.

On my '93 the gas gauge worked fine until I changed the fuel pump (which has the built in sending unit). On a few different Dakota specific forums I read of how this has gotten to be a fairly common problem even when using a 'name brand' assembly and not just an el-cheapo.

I confirmed my gauge is fine as I plugged the harness into my old pump and the gauge moved as I worked the sender by hand. Someone suggested I may have 'clocked' the pump wrong, but am doubtful as the gauge did work initially..

For how much I drive my truck, I simply reset the trip odo at each fill up and fill up again at 200 miles. Gives me plenty of cushion.