The Incredible Shrinking Gas Tank, or, WTF?

The joys of old Hondas just keep on coming. 

I have a wonky gauge cluster; some lights don't work and some gauges are very suspect on accuracy or don't work at all. One of those is the fuel level gauge. This was confirmed last Friday when the gauge read a quarter tank but I ran out of fuel. 

I poured a little over a gallon of gas into the tank and, voila, it starts right up, eager to go. Then, I go to fill-up and after pumping less than three gallons the gas pump stops and says "no more, your tank is full". WTF?

So, the tank is full but I can only use four gallons or the fuel delivery system is occupied by gremlins.

Like I said - WTF...

Is that Honda old enough to have a drain plug on the tank?  If so, get some containers, drain the tank and find out how much fuel is really in there.  That'll narrow the issue down to either a fuel delivery and gauge issue or a tank vent issue that prevents you from filling it all the way.  

just out of curiosity, the bottom of the tank is not crushed in, is it?

Had the same problem with an old car.

Tank was rusty and the rust would get sucked onto the pickup sock until it would starve for fuel.

Once the suction was gone and the new fuel was added to stir up the tank, the rust would wash away from the sock and the car would run again, until the pickup got clogged.

Repeat a couple times until I figured it out.

Maybe a clogged vent? If the tank cannot breathe to replace the burned fuel eventually it will be in vacuum to a point it won’t be able to pump any more, then once you open the cap it get back to atmospheric pressure it is fine, but won’t take much gas because it was mostly full anyway   

Hole in the fuel line inside the tank?

Like drinking from a cracked straw, it will work fine until the fluid level is below the hole.

rslifkin said:

Is that Honda old enough to have a drain plug on the tank?  If so, get some containers, drain the tank and find out how much fuel is really in there.  That'll narrow the issue down to either a fuel delivery and gauge issue or a tank vent issue that prevents you from filling it all the way.  

My old 85 Prelude Si had that.  Thought it was such a great idea and wondered why more cars don't have it.  With siphon-proof and vapor sealed necks it's nearly impossible to drain a tank to do sender/pump work.

Trans_Maro said:

Had the same problem with an old car.

Tank was rusty and the rust would get sucked onto the pickup sock until it would starve for fuel.

Once the suction was gone and the new fuel was added to stir up the tank, the rust would wash away from the sock and the car would run again, until the pickup got clogged.

Repeat a couple times until I figured it out.

I went through this exact scenario with my old Storm GSI. Dropped tank, hosed out all the loose rust flakes at the car wash, blow dried inside with a heat gun, sprayed a crap ton of Rust Converter all around inside the tank. Was good to go for another 60K miles until the supply of critical repair/replacement parts went extinct.