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rpmdiag, Tech and Instructor
Category: Car
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Experience:  Since 1975
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2004 hyundai xg300: wouldnt start..The dealer replaced the fuel pump

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My 2004 Hyundai XG350L wouldn't start. The dealer replaced the fuel pump. Two days later the vehicle is intermittently starting. The dealer is troubleshooting the problem. My concern is if nothing else is found. In fact, do we really know if the fuel pump was the problem. What is the best way to approach this issue. Perhaps test the old fuel pump?



They obviously GUESSED wrong on your behalf. The pump can be tested one of two ways, with a pressure guage to see if the pressure and / or volume of fuel being delivered are adequate or not. The other test is a bullet proof test for pump electrical integrity that can actually show you the commutator humps on the pump and see how many amps the pump is actually drawing, and what the RPM's of the pump are. Normally about 6K. A low amps probe and a lab scope are required for ths advanced testing procedure. See PICs of waveforms.


Thanks for your question,





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