Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Hi Danner, I have problem in my friend's 2007 Hyundai Verna. After a while being hot,it stalls and when starting it again it goes on . I suspected fuel pump . Finally I found that fuel pump(when key is ignition on motor off) sometimes makes sound and sometimes don't. got it out and connected it directly to battery 12V for about 3 min it operated but when connected it back to car wiring harness it didn't(did this twice) so I suspected the harness and checked it out by 12V light tester but didn't light so I checked fuel pump relay and it is OK so I believed that there is a problem in the harness but my friend changed the fuel pump and car worked fine since then.
My questions are:
How did not I get 12V on tester(did not light) and car works fine after changing fuel pump (ground checked and it is ok ) ?
What is the most effective test in this case to ensure faulty fuel pump?
Have you done a voltage drop test at the pump? That would determine if there is excessive resistance that is not allowing enough power to run the pump properly. Paul has some good videos on how to do this test.
