Fuel Gauge reads 1/4 full

[lemortede]

We have been in the process of selling our home.
To help show the parking and lot etc. I was driving the MH to work on days we had showings.
The Driveway has a dip in it that makes it necessary to take it slow.
One morning I was pulling out and was just a tad too fast and hit the rear bumper in the dip.
Since then the gas gauge has read 1/4 of a tank.
I have seen it spontaneously read correctly for a split second after its been sitting for a bit.
I pulled the gauge's to see what is being sent to the Fuel gauge.
Its around 35 ohms which on a 90 ohm gauge is about right for what I am reading.
I believe the gauge is good as I can manipulate the gauge reading by varying the ground resistance on the post behind the F.
(E side is + and the post behind the F is ground that goes to the float.)
At this point I am leaning to it being a bad float assembly or maybe a bad ground at the tank?
The float assembly makes the most sense to me since if it was a bad ground I would think the resistance would always be high and the gauge would read fuller than it does.
I am kind of thinking that perhaps it may be the wire its self since I seem to get a constant 30ish Ohms. Maybe the wire its self is grounding to the frame before it gets to the tank? Depending on where it is and the rust on the frame I could see 30 ohms being a possibility.
Anyway, I may be thinking about this all wrong and just need another brain to help either set me strait or validate my process.

[legomybago]

Looks to me like you are on the right trail....Time to look at the sending unit. That's where I would be. But maybe I'm wrong too i?? lol

[Rickf1985]

The fact that this happened at the same time as banging the ground I would be looking at the wiring under there. See if a wire hot scraped or broken. Scrape a small spot bare on the tank and attach a ground wire to it and then to a good ground. I usually use a jumper right to the battery ground. If the gauge now works then the ground to the tank has been compromised somehow.

Using a jumper right to the battery ground whenever checking bad grounds eliminates any possibility of multiplying your problem by not getting a good ground on a rusty chassis. If it works good directly to the battery but then later it does not work when you hook to the frame you know you have more grounding issues between the frame and battery. Sometimes a bad ground is not a total loss of contact, it can be added resistance which can really raise hell with gauges and sensors.

[jeno]

Very well put you just made me understand quite a bit of things that I didn't understand before thank you...