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Sportage won't start with less than 1/4 tank of gas

My 2009 Sportage gives me a hard time if I have less than 1/4 tank of gas. I have used a tank cleaner for any sediment, but that didn’t help. I had a mechanic look at it, but the computer said nothing was wrong. I realize I could not let it get down to 1/4 tank, but that is beside the point - the car shouldn’t do this.

How many miles on the Sportage?

Usually hard starting when the fuel level is low indicates a failing fuel pump. During the start cycle, the ECM computer is running open loop and as such will not set a mixture related DTC. You might throw a fuel pressure gauge on the line and see what the fuel pressure is reading when the fuel level is below 1/4 and having difficulty starting.


I’d venture to wonder if your gas gauge isn’t off and you’re actually out of gas at a quarter tank. I have seen plenty of gauges through the years show a quarter tank and the car is really out of fuel. if this were my car and something like this weren’t covered under warranty, I would just remember that a quarter tank was empty.

This sometimes happens on my 1999 Honda Civic, although at nearly empty, not a 1/4 tank.

I have found if I turn the key to on for a couple seconds, then off, and repeat this cycle three or four times, the car starts OK.

My vote is for an erratic fuel gauge at this point. When the gauge is on 1/4 tank fill it up, see how many gallons it takes, and then compare that to what the tank is supposed to hold.

If the gauge is accurate then your problem is not the amount of gas in the tank, with one caveat. That would be if the vehicle is parked on a slant of some sort.

Another possibility is improper tank venting. It manifests when the tank gets low because the tank isn’t equalizing pressure, which means the fuel pump has to work extra hard to pump the fuel (picture drinking a milkshake with a pump on the other end of the straw trying to suck in the opposite direction - you’d have to work a lot harder to overcome the suction).

Really easy to test this one - let it get to 1/4 tank, and when it doesn’t want to start, remove the gas cap and try to start it again. If it starts, your tank isn’t properly venting, and removing the gas cap broke the seal and allowed it to vent.

To add to what shadowfax said, if you remove the gas cap when you get to a quarter tank, is there a hiss from air rushing in?

Wow, such great ideas.
The car only has 33,000 miles on it.
The gas gauge is an easy test and I’ll do that next time I fill up (though last time it didn’t want to start on me, it had more than 1/4 tank).
Gas cap removal check. Failing fuel pump - can I just open my hood and look for this? Actually let me say that once it starts and I fill it up, it never stalls on me. The problem is ONLY when I start it…kind of rules out fuel pump, doesn’t it?
How do you fix the improper venting aspect if that is indeed it?

Thank you all so much.

I appreciate it. Great car otherwise!