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Ron, ASE Certified Technician
Category: Mercury
Satisfied Customers: 33049
Experience:  ASE Certs and Ford Certs
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My name is ***** *****. I have a 2000 sable with the 24v

Customer Question

Hi my name is ***** *****. I have a 2000 sable with the 24v dohc engine .Now always but sometimes it won't start. The engine will crank . I can crank it several times. as long as I don't turn the key to off it won't start. If I turn it to off it will start and run. Many times it will run fine. twice it has stalled when backing up and the same cranking thing happens. It has a code p0191
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Submitted: 6 months ago.
Category: Mercury
Expert:  Ron replied 6 months ago.
Hello and thank you for your question,The code P0191 indicates you have a fuel pressure concern usually meaning the fuel pump is slow to prime. Will it start and stay running if you cycle the key off and on a few time before you try starting it?
Customer: replied 6 months ago.
Hi , I haven't tried cycling the key without starting it. If I turn the key off then on it will start and run.
Customer: replied 6 months ago.
Today it is running fine.
Expert:  Ron replied 6 months ago.
The common cause for this type of problem is in most cases caused by the fuel pump loosing its prime, the fuel pump has a built in one way check valve that allows the pump to hold pressure on the first turn of the key so the car can start and when they fail it take a few cycles to get the correct pressure to start the engine. You can usually check this by cycling the key of and on a few time before you crank the engine , if it then starts the problem is usually a failing fuel pump and replacement is needed. I have also enclosed the complete testing steps if you want to test it to verify before replacing it. Copy and paste the link to your browser to open and view it. Post back if you have more questions and or need more help.
Customer: replied 6 months ago.
Thanks , sounds like you are leaning toward the pump. There is a pressure reg on the fuel rail , then a short hose to a round diaphragm. could there be a problem there? I am changing the fuel filter also and swapping the relay with the one next to it.
Expert:  Ron replied 6 months ago.
Yes the regulator simply regulates the running pressure and if the pump is slow to prime the regulator can not regulate the pressure. This dose sound like a failing fuel pump which is the most common cause and will also cause the fuel pressure code P0191 to set. Running the test steps will verify this as well.
Customer: replied 6 months ago.
Thanks Ron, I don't have a gauge. I will have to get one. I am a old muscle car guy. Was that yes to pressure reg could be the problem? there is junk yard near by that has one sitting that I could get those 2 parts from . tank is 3/4 full .
Expert:  Ron replied 6 months ago.
Its not likely the regulator is going to be a problem, it most likely the fuel pump loosing its prime which is very common on the 2000. Cycling the key a few time when it will not start is a pretty good test as well. If it starts after cycling the key a few time your looking at a bad fuel pump.

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