So here's my problem:

I made the 360 mile drive home today. Filled up beforehand. at 150 miles I looked at my fuel gauge...said 1/2 tank, which is about right. Looked down at 175 miles and it was 1/4 full. I watch it for 3 miles after that and watched it steadily go to EMPTY and the idiot light came on. Luckily I was by a gas station so I pulled in and filled up, also looked for leaks/under the hood for any smells. I put 8 gallons in until it clicked, then tried to top it off just in case. My mileage came out to 21 mpg which is normal, AFR was also normal. Started the car and it still was empty. Over the next 50 miles it slowly went all the way to full, then back down to 1/2 tank, then fluctuated from 3/8 to 3/4 full!. I stopped and put more gas in, 6 gallons this time at 23 mpg. Started the car again and it went up to 3/4 of a tank and in the 30 miles I drove home, it went from 1/2 a tank to 7/8 full. The weird thing is that if I boost or brake hard, I can get it to fluctuate.

The car has a walbro 255 in it, but that was put in at least a year ago.

I'm thinking the sensor arm might be hung up on something, but I'm not sure. Any thoughts?

 

i agree pull the pump and check the arm out.....might have gotten gunked up or just acting funny

 

mine does the same sometime, just not as broad as yours... between half and 3/4... it will go down to half tank, then i will park. Next time i get in the car its back up, then drops under half tank pretty fast after i get going.

 

That's what is weird though. Mine has never done this before. It has actually been really accurate. And to do it in the middle of a 5 hour drive is even weirder. I would have expected it to start happening as soon as I pulled out of the gas station

 

pull your fuel pump put, take a look at the floater...and go from there.

 

mine fluctuates up and down, all of the time. but not drastically, like ~ 1/8 of a tank. Its starting to irritate me...

 

i did this when i put my 255 in and its still doing it lol. doesnt really bother me much. i just watch the mileage