Fuel system

PETAR LJ

MEMBER
2004 HYUNDAI SANTA FE
2.6L
V6
4WD
AUTOMATIC
180,000 MILES

My car stops at random it seems to fold and smell a pungent smell. It does it at random hot cold sometimes it will start up puffs out black smoke runs badly until it gets going.

Thursday, April 28th, 2022 AT 7:18 AM

5 Replies

JACOBANDNICKOLAS

MECHANIC
109,867 POSTS

The black smoke indicates a rich fuel mixture. Here is what I suggest. First, the odor may indicate the catalytic has already been damaged, so we need to check the fuel pressure to see if it is too high.

Here is a link that explains how it's done. Do this and let me know the results. Also, let me know if the check engine light stays on when it's running.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Let me know if you have a scan tool that has live data as well.

Take care,

Joe

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Thursday, April 28th, 2022 AT 7:18 PM

PETAR LJ

MEMBER
32 POSTS

Hi there again, thank you for your reply. The vehicle has a new fuel pump, fuel filter, crank sensor, temperature sensor, and an air control valve on throttle body. The fuel pressure was good when fitted it, fuel pressure regulator good, not only it stops at random hot cold it may restart and may not if it starts, the engine revs will start hunting up to 2,500 RPMs, then the next morning it will be fine for a few days maybe weeks until it mucks up again. I have been disconnecting the earth lead at times to then reconnecting to restart the vehicle it just comes and goes new leads plugs inlet and exhaust manifold gaskets, injectors pulse leads spark.

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Thursday, April 28th, 2022 AT 11:37 PM

JACOBANDNICKOLAS

MECHANIC
109,867 POSTS

Hi,

One other thing that may be failing is the engine coolant temperature sensor. The signal is used by the computer to determine what the air/fuel mixture needs to be for a specific temperature. If it is failing and indicates to the comp that the temperature is -40F, the fuel mixture will be too rich.

By chance, do you have a live data scan tool? If you do, when the engine is cold, check the ECT signal to determine if it is accurate. The issue is this, however. It is an intermittent issue so it may work one time and not the next. So, it may be difficult to get an accurate reading if it is running correctly. In that case, see what the ECT signals when the issue is happening.

Also, if you do have the scanner, let me know what the short-term fuel trims are. Something is causing too much fuel to the engine. That is what the black smoke you mentioned is likely being caused by.

Let me know if that is something you have and can do.

Take care,

Joe

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Friday, April 29th, 2022 AT 7:05 PM

PETAR LJ

MEMBER
32 POSTS

Hi there, the engine temperature sender unit was replaced, I did have the computer scanned only found in the history that there was a problem with temp unit, though it may be an electrical problem due to disconnecting battery and the car starts up again finally, this problem happens at random hot, cold any time it fuels up stops, then when it starts up again motor starts hunting, then the problem just stops and runs great until it starts mucking up again. This has been going on for the past 2 years.

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Saturday, April 30th, 2022 AT 7:39 PM

JACOBANDNICKOLAS

MECHANIC
109,867 POSTS

Hi,

I didn't realize the sensor was replaced. However, it would still be a good idea to check what it is signaling. What makes it difficult is what you likely already know. It's random.

When the problem exists, do you always have the odd smell and black smoke from the exhaust? Also, do you have a live data scanner? It would be helpful to know what is happening when the problem exists. For example, is the ECT signal completely off, or is the air/fuel mixture off.

Interestingly, the odd smell is likely coming from the catalytic converter. So, something is causing the fuel mixture to be too rich.

Take a look through this link and let me know if it is helpful:

https://www.2carpros.com/articles/engine-black-smoke

Let me know.

Take care,

Joe