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Need help cant figure out why my car wont start

05 Mercury mariner I’m having trouble with my car not starting. It cranks but will not turn over. I have replaced the fuel pump, fuel filter, and the fuel rail pressure sensor. It seemed like it’s not getting gas and I can not figure out what else it could be. The fuses and relay are fine.

Cranking and turning over are the same thing.

Have you tried introducing starting fluid into the intake to see if it runs for a second or two?


Don’t take me as an expert but a quick check to see if there is spark will indicate a fuel problem. Then you really need to do a fuel pressure test to determine if it is fuel. When you turn the key on, the computer will cycle the pump on for a few seconds and then full on if it starts. So do you hear the pump running for a few seconds when you turn the key on? If it doesn’t run and the connections and relay are OK, it could always be the computer not signaling the pump to run. I do believe though computers don’t go bad that often. Like others have said too, if the computer doesn’t see the engine cranking such as if a bad crank sensor, that could be it. Really though it might be time for a shop diagnosis if you don’t have the tools and diagnostic charts.

Yes starter fluid we get it to start but will only run for about five seconds

Then that means the engine has ignition, but no fuel.


Then I think your fuel pump is not running for whatever reason. Use a test light at the factory test terminal to see if you are getting power if you can’t hear it run. I’ve also had bad connections at the pump.

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What would be causing my pump not to get power

Blown fuse, corroded connection, bad replacement pump, tripped fuel shut off impact sensor if so equipped.

If you can hear the fuel pump when you turn on the ignition you have power. Have someone turn the key on and off while you listen near the fuel tank. If you don’t hear anything then test for power to the pump. If no power to the pump it is an electrical problem. See if you have another relay with the same number as the foe; pump relay and swap them/

Your next check should be to see if the fuel pump is getting power. It is possible that the fuel pump is bad. You also may have just a clogged fuel filter causing the trouble.

Just to muddy the waters a little, the shop I used said they had three Delco pumps in a row that were no good. Some years ago but it is not unheard of to get a bad pump. Also I have been told that testing them dry first ruins them. Also you are supposed to change the harness to the pump when you change pumps and also change the relay. I’ve had my share of pump problems.