Gassy Festy

[RoushRacing99]

Hi all

I have a 1990 Ford Festiva I bought several months ago. It has been a project for this whole period and is getting drivable now.

It gets very poor fuel milage(17-20 mpg)

The fuel filter has been changed, it is a 5 speed, it fouls spark plugs on 2 cylinders

It always smells extremely gassy, I have messed with the idle and the timing as much as possible and it just doesn't help.

Any ideas why such bad fuel economy?

[Aaronbrook37]

Start with the basics... ensure that the VAFM and O2 Sensor are operating well and are clean. Electrical cleaner will work for the former, and gasoline for the latter. Once you've got that nailed, then we'll see how things go.

Also ensure that your tires and tire pressure are up to spec, that you aren't constantly driving the heck out of the motor/transmission, and other fuel economy basics. But at sub-20mpg, you're having serious issues. I suspect either VAFM or O2S, perhaps even both to be honest.

Ensure your plugs and wires are both good, and the air filter as well. Also take a look at your thermostat and ensure it's operational. If it's not permitting things to run hot enough, you could be stuck in closed loop.

[FestYboy]

Also take a look at your thermostat and ensure it's operational. If it's not permitting things to run hot enough, you could be stuck in OPEN loop.

also be sure to check the opperation of your injectors (make sure they're clicking, especially the ones associated with the fowled plugs. if your injectors are sticking open, they will cause those cylinders to run rich and likely fowl. and replace the fowled plugs, its not doing you any good to test with bad plugs.

[TominMO]

Welcome to the site! It will help you and us if you put your location in your profile.
Go to User CP (top of the Page in the blue bar)
Control Panel(left side of screen)
Edit Your Details-scroll to bottom of page to Location.

Also, about the gas mileage, make sure your parking brake is fully disengaging.

[Aaronbrook37]

also be sure to check the opperation of your injectors (make sure they're clicking, especially the ones associated with the fowled plugs. if your injectors are sticking open, they will cause those cylinders to run rich and likely fowl. and replace the fowled plugs, its not doing you any good to test with bad plugs.

Oops sorry... thanks for the coverage, good sir! This is why I shouldn't reply to technical threads before 9AM haha.