Mazda 626 fuel issues

1996 Mazda 626, 4 cyl., manual, 123k miles. I’ve been driving it the last 6 years, before that my old man drove it for about 5 years. He bought it used. Note that the “CEL” light never comes on. Also, note that I live in Nebraska and as far as I know there are no emission standards to worry about.

I have 2 questions, to which I’ve seen various answers on this site and around the web. Please don’t advise that I use the “search” feature; trust me, I’ve already read everything and am looking for clear and (hopefully) non-conflicting advice. Thanks in advance - you guys are the best.

(1) The gas gauge on my car never moves above about 2/3’s full, no matter the amount of gas in the car. Once the actual level of fuel in the tank moves below 2/3’s, the needle moves normally. However, this hasn’t been as much of an issue lately (lately meaning the last year or two), because:

(2) I can’t fill up my gas tank to full. When I started driving it the car was hard to fill up and my old man advised pulling the hose out an inch or two, or turning it so that I could fill up to a full tank. That worked for awhile. For the last several years my technique was to squeeze gently the hose handle to avoid the automatic trip-off, filling until it wouldn’t let me anymore, usually around 8 gallons (the tank should hold about 14). It got worse over time. Today I went to put gas in as I was almost on empty, and I couldn’t put more than a few seconds in at a time; I finally gave up after about 3 gallons.

I read that “Doc J” explanation about how the fuel/emission system works generally. I’m a college student and don’t have the cash to do major repairs, plus the car itself works fine and longest I ever have to drive is about the 90 miles home, which is no problem. If the problem is a stuck cut-off valve that be be fixed via bent coat hanger, I may try that. If the problem is an overloaded charcoal/carbon filter that costs hundreds of $$$ to fix, then I’ll just live with it. I’ve also read elsewhere that I could try unplugging the vacuum tubes from my EVAP purge solenoid valve to relieve the built up pressure. I’ve located this in my car but right now am unsure about whether/how to disconnect the appropriate tubing. Finally, to fix the gauge problem I’ve read a fuel cleaning additive might help, although I’m skeptical. Otherwise I’ve read that replacing the fuel sensor itself is not too difficult, although I’d prefer not to shell out cash for a new one.

Regarding “topping off,” I can’t comment on what the previous owner or my dad did when they drove it. I usually try to squeeze a little more into the tank once it automatically clicks off, although like I said above, I don’t believe I’m ever getting too close to “full.”

Do you guys have any advice? One unresolved main issue I’ve seen on these boards is whether the charcoal filter has an effect on filling the tank, or whether this is just a faulty valve in the gas input. It seems to be that when filling the seal must be broken and air can get out that way, but I (obviously) don’t have tons of experience with this. Thanks again.

On your 1996 model year car, don’t worry about the EVAP system preventing fuel filling. On many cars, there is an anti-spill valve (or ball) that may get stuck in the closed position. It sits where the fill tube connects to the tank. A flexible stick can be used to dislodge it.
There is a vent tube inside the fill tube. It may have become out of position. You can get another tank fill tube at a salvage yard. It would be cheapest at one of the “u get it” places.