High fuel consumption, overpressurized fuel tank tercel

[Esaus]

Hi!
I have a little side note if someone might have need of this in the future.I have already fixed the issue but im sharing my findings to members.

I belive this is good to know information in these aging cars and rusty fuel pipes and hoses that deteriorate over time.

I had an ongoing issue with my Tercel that the tank would hiss and be overpressurized a while back. I had a leaking tank so it wasnt much of a thought, but since i fixed the leak the issue became much worse. Ive also noticed a high fuel consumption on the car but i also recently changed to much bigger tyres so i thought it might have been that. Car would also feel sluggish, but as i said the tyres are much bigger as i wanted a lift to the car so i thought it was this.

I would also often get a loud hissing blowing sound when i opened the fuel cap. I started having a loosely fitting fuel cap as a solution to this to allow the excess fuel vapour out or pressure to equalize. I started having issues as the weather would get hotter that i had fuel leaking from the cap when its parked. It was gushing out. And when i would open the cap my hand would be dowsed with a few deciliters of fuel gushing out!

I started looking into a solution and thouhgt it might be with the fuel venting pipes. I checked the workshop manual that i have and it describes a coal filter before the carb. I however have a Swedish tercel and mine doesnt have a coal filter. It turns out it vents to atmosphere under the car near the tank.

I checked the pipes and they were rusted solid and the one direction valve was clogged aswell. Ive now replaced the pipes with copper tubing and now the tank vents again. Ive test driven the car and it feels like it has more power again and it seems the fuel consumption is better again.

Before it was close to 9.5/100 km but now its closer to the original of maybe 7.5 lr or so.

I think that its a good idea to check that these pipes are free of rust and allow the fuel vapors to either escape to the carb or to atmosphere.
In my case i think it was causing a high fuel pressure and forcing more fuel into the carb pushing past the float bowl needle causing high fuel consumption.

I hope this helps people out!

//Esa From Sweden!!

[dlb]

That's interesting your car doesn't have a charcoal canister to capture fuel vapors from the gas tank. I removed the charcoal canister on a previous car and noticed a strong gasoline smell from the pipe that used to go to the canister. Eventually re-installed it because I couldn't stand the gas smell all the time. I'm surprised you don't notice that with yours not having a charcoal canister.

Good work finding the cause of your pressurized gas tank though!