2004 Hyundai Sonata Runs Rough and Stalls

FDEGREE

MEMBER
2004 HYUNDAI SONATA
4 CYL
FWD
AUTOMATIC
95,000 MILES

Sometimes the car runs beautifully. Other times is starts spark knocking, lurching, minimal response to accelerator positioning, occasionally stalls…almost like it is running out of gas. I have tried a gas additive to get rid of any potential water in the fuel tank, over the course of 3 tank fills…didn’t help. The fuel level doesn’t seem to have any impact on the problem. It flares up with ¼ tank and also with ¾ of a tank.

The codes show random cylinder misfires.

It will sometimes run great for a few days, then it will act-up for a day or so.

Any suggestions…

2 Replies

DOCFIXIT

MECHANIC
18,828 POSTS

Sounds like you have a possible fuel pump issue. Check pressure when it screws up. Also post the code numbers

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Friday, July 25th, 2008 AT 8:28 AM

FDEGREE

MEMBER
3 POSTS

As I understand it, there is no easy way to check fuel pressure. Apparently, it requires disconnecting the fuel lines from the fuel rail and inserting some sort of adapter.I'm not sure I have that information correct, but that is how I understood what was told to me. I do know there is no direct crew-on connection for a pressure guage anywhere on the fule line.

Considering the need to purchase this adapter, I think I may be just as well off dropping the fuel tank and replacing the fuel pump. Hoping it will solve my problem.

If it acts up again, I'll try to write down the codes so I can post them.