2004 Scion XA went from 32mpg to 20mpg

I had the thermostat replaced because the mechanic thought the car was running cold and sending rich fuel to the engine. Also I think the solenoid is bad because now car won’t start.

OK, start by getting a new solenoid.

No one can give you any real help with the info you’ve given.

Tell folks all about the basics with the car. Mileage, maintenance history, and history of symptoms at minimum. When you describe symptoms, note that saying something like “won’t start” doesn’t say anything. There are 100 things that can happen when one turns the key and the engine “won’t start.”

The car has run perfectly for eight years, it is only in the last month that the mileage has dropped drastically. The fuel gauge would read full then go down an eighth of a tank in thirty miles, now it has a little over half a tank and has gone 77 miles. The car has 145,800 miles on it and has been maintained, i just had an oil change, air filter change, thermostat changed the coolants were flushed and pressure tested.

Have someone connect a scanner to the vehicle and monitor the coolant temperature sensor. If this sensor has failed where it’s telling the computer the coolant temperature never reaches operating temperature, the computer will think the engine is still cold and the fuel mileage will be poor.


They did replace the thermostat after testing the coolant temperature sensor but the mileage is still bad. I notice when I pump the gas that the pump wants to keep shutting off and I have to hold the pump the whole time squeezing it so the gas comes out.

It sounds like you’re using the fuel gauge as a way to approximate gas mileage, which is inaccurate and unscientific. You need to drive the car for an extended period of time, topping off the tank at each fillup and resetting your trip meter, and then for each fillup write down the number of miles versus how many gallons on the pump it took to fill up. Average several tanks worth.

On my vehicle, the first quarter tank on the gauge can be anywhere between 40 and 75 miles depending on driving style, city/hwy, pulling a trailer, etc.

“I notice when I pump the gas that the pump wants to keep shutting off and I have to hold the pump the whole time squeezing it so the gas comes out.”

Can you clarify that? What are you “squeezing”? Are you just saying that you have to keep on the gas pedal or the car stalls? If so, you are not giving it gas. You are giving it air. The computer does the gas. Are you ever smelling gas? Seeing any smoke out of the tailpipe? Is your check engine light on? It needs to go back to the mechanic as you very well may be running rich but for some other reason such as a leaking fuel pressure regulator or fuel injectors.

CCCommander35 is right about gas mileage calculation, btw. Except don’t “top off” the tank. Just go with the first auto shut off and calculate mileage over several tanks of gas. Otherwise you’ll soon run into issues with your evap system.

Good catch cigroller, thanks for noting that…I innately think of “topping off” as the first shutoff click of the pump, but it’s important to distinguish that.

I am squeezing the pump to get the gas to come out, it comes out slowly and tries to ‘click off’ even though i could have an empty tank. The check engine light is not on the maintenance required light is on. I never smell gas or see smoke out of the tailpipe. It is going back to the mechanic tomorrow.

Along with your other problems, check to see if you have a dragging brake…A sure mileage killer…

Good advice so far. But I fin dmyself wondering what “has been maintained” means. Are you still driving around on the original sparkplugs? Have you been doing all the maintenance recommended in the Owners’ manual?

The MOST COMMON cause of this happening is poor maintenance Air filter clogging…etc… AND OR An O2 sensor issue…I’d have to say the O2 is THE most common culprit…but that would throw a CEL…a clogged air filter WILL NOT…so what have you…codes or no codes?