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Matt, Engineer
Category: Mercury
Satisfied Customers: 21617
Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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The car will not stay running after the ignition switch has

Customer Question

The car will not stay running after the ignition switch has started the car
Submitted: 1 year ago.
Category: Mercury
Expert:  Matt replied 1 year ago.


this sounds like a lack of fuel and could be a lack of fuel pressure from the electrical pump at the tank.

If the connections to the pump are corroded or damaged then the pump could stop at any time or could not be running at full speed. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse,
Ideally measure the pressure at the injectors and if this is low check the pump as described and also consider changing the fuel filter as if this partially blocked this too will reduce pressure.

Customer: replied 1 year ago.
This is not the problem at all. I guess I did not explain it properly. I turn the key and engage the starter. The car starts while I hold onto the switch and let it turn back a bit to disengage the starter. The car runs fine while am holding onto the key. The car stays running until I fully release the ignition switch into the run position. Then the engine dies.
Expert:  Matt replied 1 year ago.

Thanks for the extra information

OK this sounds like the fuel pump isn't being held on by its relay

this relay is normally switched via the ignition switch and the relay held on once the engine is running

so I'd suggest replacing the fuel pump and the ECU relays that shoudl be located in the engine bay fusebox

Expert:  Matt replied 1 year ago.


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