Why will my car have trouble starting in hot weather and get bad gas mileage?

ROBERTSCHNITKER

MEMBER
2004 CHEVROLET MALIBU
131,000 MILES

My 2004 chevrolet malibu classic usually starts in cold weather but gives me trouble when it is warm outside. If it is warm outside the car has problems starting and will sometimes die while coming to a stop. It has lately been getting extremely bad gas mileage. Im only getting maybe 250 miles a tank. I have replaced fuel pump relay, fuel pump, spark plugs, fuel filter, fuel pressure regulator, and was told to check asd but it is built in with the fuel pump relay. So I do not think it is that. Also when the car is not starting I do not here the fuel pump prime, which thought could be bad wiring but bad wiring shouldn't cause bad gas mileage. Was told by one mechanic it could be a bad sensor, but which one would give all of these problems?

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

Normally a hard to start vehicle is due to low fuel pressure. However, with you getting a hard to start in warm weather and poor fuel mileage, I am thinking you have a leaking fuel injector.

Here are a couple guides that will help with this issue:

https://www.2carpros.com/articles/engine-cranks-excessively-before-starting

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

If we find that we have a leaking injector then clearly we need to replace it but the easiest way to find this out is when it is not starting do a clear flood start. You do this by holding the accelerator to the floor then crank the engine. This will cut the injectors and if it starts then you have a leaking injector.

Take a look at the info below on this and let us know what you find with this.

Thanks

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