Gas gauge doesn't go to full when I fill up

[91Pioneer]

My truck has been doing this since I got it but I just honestly haven't bothered to really look into the issue.

 

When I fill the truck up, the gas gauge needle goes a bit higher than 3/4 but never gets near full. Any ideas? I have changed the gauge cluster from the partial to a full set of gauges so I know the needle is not just out of place, since it did the same behavior on both clusters.

[87MJTIM]

There may be something in the tank that is stopping the level float from lift up all the way.  Have you removed the pump/sending unit to inspect for any obstructions?

[91Pioneer]

No I've been lazy LOL I guess a physical check of things should probably be my next step but now the tank is full.

[Minuit]

I have a similar problem. Immediately after filling up the gauge goes to 1/2. After about 30 miles it starts going up to 3/4, and from then on consistently reads 1/4 lower than the true value. It's been doing this ever since I've had it, both with the basic and full clusters. Do you know if the tank has been replaced? It's been replaced on mine and I have a feeling that something wasn't exactly put back right when it was done.

[91Pioneer]

I should add that the gas level on the gauge does not stay up high until the gas goes down, it kind of hovers around the 3/4 mark basically and drops steadily. So I kinda suspect that when the gauge says empty it's not really. I'm not willing to run it out of gas though. I just keep putting in gas when needed, fortunately it's not a big deal.

 

My tank is rusty and appears original. Same for the pump.

[tugalo]

mine goes from full to 1/8 tank within 75 or so miles and then stays there till almost emply.  I haven't had the guts to run it to emply either...........

[gogmorgo]

Mine also does that. I'm assuming it's just old corroded wiring causing the problem. While it seems reliable, about a third of my parents' vehicles had malfunctioning gauges, so I've always just used the trip meter to keep track of how far I've gone between fill ups. Haven't run out of gas in the MJ yet, even after having gone 175km with the low-fuel light on. Based on known tank capacity and how much I put in, the light consistently comes on around 1/3 tank. The needle does give a general idea of what's in there, as in it starts around 3/4 or so and wanders down towards empty, but it wanders kinda drunkenly, going up or down by as much as a 1/4 tank seemingly randomly. I blame it on the old wires.

[mikekaz1]

the "wandering needle" is typical of many older vehicles as the gauge is normally a direct reading of float level. as the fuel moves around the float adapts with that,  giving the odd readings while driving,   same with the oil pressure,    the computer systems of newer vehicles intercepts these signals to give a more consistent or preferred reading because of people complaining of it over the years

[gogmorgo]

Mine wanders around when parked on level ground. Unless there's something swimming around in my tank... Old crappy wiring.