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Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3342
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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There, I have a 150 jp Johnson 2003 model , it will fire up

Customer Question

Hi There, I have a 150 jp Johnson 2003 model , it will fire up but won't keep running . Fires for only a couple of seconds . Carnies have been kited, power pack and optic sensor are new . And running electric fuel pump at around 4psi . If you have any ideas could you please let me know . Cheers Chris
Submitted: 6 months ago.
Category: Boat
Expert:  Jason replied 6 months ago.

Hi Chris, my name is Jason.

The electric fuel pump is a big no no, it is not safe nor legal to use one, the engine was never designed to have one either.

That being said, have you checked engine compression and spark output yet?

When was the last time the engine ran?

How old is the fuel?

Will the engine run at a faster rpm if you rev it up?

Customer: replied 6 months ago.
It's been running for years with the electric pump from when I got it a few years back . Compression is even and spark is bright and strong . Fuel is new
Expert:  Jason replied 6 months ago.

What are the actual compression numbers? Numbers are important, once it gets to low it won't run.

Customer: replied 6 months ago.
Compression is 110 psi per cylinder or extremely close too each other
Expert:  Jason replied 6 months ago.

Will the engine run at a higher rpm if you rev it up?

Customer: replied 6 months ago.
As soon as I lift the warm up lever it won't start at all just fires
Expert:  Jason replied 6 months ago.

Locate the fuel primer, it will have a red lever on the side of it. Is that lever pointing in towards the primer, or pointing away from the body of the primer?

Customer: replied 6 months ago.
It's pointing at the body of the primer
Expert:  Jason replied 6 months ago.

Turn the lever away from the body of the primer, let me know if the engine runs any longer or better.

Customer: replied 6 months ago.
No it doesn't , still fires but won't run
Expert:  Charles replied 6 months ago.

Hello Chris, my name is***** will assist you from here.

When you are doing the cold start, even with an electric fuel pump, you still need to be using the enrichener to prime the engine with fuel. Hold the key pressed in as you are cranking the engine over. If you are also using premixed fuel and oil, it ill take a bit longer to fire, as it is rich for a cold start. When it does fire up and runs for just a brief moment, press in and release the key switch a few times to see if it will stay running.

Make sure that the mixture screws on the carbs are set correctly. They should be 5 turns out from a light seat, and may need slight tweaking from there.

Verify that the mechanical timing of the engine is correct. When the Number 1 piston is at TDC, the 0* timing mark on the timer wheel should point at the arrow.

Let me know what you get.

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