Q: 2012 Malibu won’t start. Unplug the fuel pump relay for 10 sec it starts right up. Got new relay started 4 2 wks.

asked by on December 20, 2017

Car wouldn’t start, would just turn over. Unplug fuel pump relay for 10 seconds, plug back in and it would start right up. Replaced fuel pump relay and it started for over two weeks with no problem. Today after starting fine this morning went to the store, came out and it wouldn’t start. This time it would start and then die immediately. After about 5 times off that and pulling and plugging back in the relay and that not working I left it alone for about 45 minutes. I decided to try it again and it just turned over didn’t start at all this time. So I pulled the fuel pump relay plugged it back in after about 10 seconds and it started right up. It did smell like it was running pretty rich when it did start up. I would think of the fuel pump was bad it just wouldn’t start at all but I can’t figure anything out. Thanks for any help!!

My car has 64800 miles.
My car has an automatic transmission.

You may want to check to be sure the fuel pressure regulator is working properly. The fuel pressure regulator is a device which controls the pressure of fuel supplied to the fuel injectors on an engine. This works by bleeding off a portion of the fuel flow to the injectors from the fuel pump to control the fuel pressure. Fuel is pumped from the fuel tank to the fuel rail by the fuel pump. The fuel pressure regulator is normally mounted after the fuel rail to ensure that the fuel rail has priority in fuel flow. The valve in the regulator controls the amount of fuel that is bled from the fuel rail by opening an outlet port to allow fuel to flow back into the fuel tank. All injectors need a pressure difference between the inlet and the outlet of the injector to spray fuel into the combustion chamber. This is called the base pressure. If this is not happening correctly, you will experience intermittent fluctuations in starting and maintaining the engine running as you have described. I would suggest having a professional from YourMechanic come to your location to diagnose and inspect your vehicle.

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