Gas gauge sometimes works 1995 dodge b2500 van

If your fuel gauge is showing you in accurate readings this is normal to all vehicles that are not used to fill-up gas full regularly but sometimes the cause of the inacuracy is due to faulty float valve in the gas tank you need to replace it

Probably a bad sending unit in the tank,or maybe a broken tank baffle.(Either way,you're looking at taking out the tank to find out.

Could be different problems.
The cluster issue could be a problem in the printed circuit board inside the cluster.
The cooling fan problem could be low coolant, a blown fuse, a faulty temp sensor, fan motor, or relay.

I would look for a loose wire in the gauge circuit, most probably on the tank unit. The other possibility is the instrument panel voltage regulator which supplies regulated voltage the the panel gauges. Mostly these are built into the fuel gauge, so if faulty, the gauge itself will have to be replaced.

The float inside the tank needs to be replaced. or one of the wires has a small short in it.

I'm not a mechanic but i had the same problem for 2 years with my 98. I fixed it yesterday. You have to repair or replace the gauge. Start by pulling the trim piece off the gauges.(it just pulls off, no screws.) Then there will be four screws that holds the instrument panel in place. Remove the instrument panel. on the back of the panel there will be four more screws, this will give you access to the gauge. twist and pull the gauge out and replace or clean the contact plugs. I had to fill the gas tank up to make sure i got the indicator needle in the right place. (to make sure the tank was full when the gauge said full) This worked for me, hope it works for you. GOOD LUCK this only takes about 45 min. from start to finsh

When gauge is pegged at full, usually means a bad ground. Check wires at fuel tank, wiggle around, maybe one came off. The bad news is it is hard to get to without removing the tank. Sometimes you can reach arm in and get to them. Also check body ground at read of van.

there is a fuel senor inside of the tank and it could very well be the problem

Before you start your van, and the key's are on accesory. Does your needle move? If it does, your gage is good and you have a bad ground or wire harness. Worst you could have a bad  sending unit and that is in the gas tank it self. Start with checking all the wire connection. Good luck.

It could be your fuel pump with your car not running right, the gas gauge thing i have no clue maybe the sensor inside the tank is messed up. or it could just be your fuel filter not doing its job. Htere are a few things it could be I would say Fuel Filter, Pump and maybe a vacume (spelling) problem, I would need to be there and hear it running or drive it to really figure out what it is