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Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3933
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I have a 1997 Johnson/OMC 150 HP Outboard which is fuel

Customer Question

I have a 1997 Johnson/OMC 150 HP Outboard which is fuel injected and will not maintain an idle. I've installed a new fuel filter, cleaned the spark plugs, added fuel treatment to the gas tank and have ran in many time but it still won't maintain an idle. Any idea where I might troubleshoot?
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.

Hello, my name is***** will assist you.

Expert:  Charles replied 1 year ago.

Verify that the fuel pressure coming from the electric fuel pump is at least 34 PSI. If it is not, the ump will need to be cleaned or replaced. Also ensure that you are firing on all 6 cylinders. If you are not, swap the coils and see if the spark will follow that coil or remain on one cylinder. If it follows, replace the bad coil. It it remains on the same cylinder, you will need to test the input.

Customer: replied 1 year ago.
I can't continue at this time but the engine is firing on all 6 cylinders, the compression on each cylinder is good (120PSI). Do you mean the fuel pump (ump?). How do you actually check the fuel pressure?
Customer: replied 1 year ago.
I was waiting for a reply since yesterday and I will get in touch tomorrow, thanks
Expert:  Charles replied 1 year ago.

Yes, the electric fuel pump. There is a test point at it that you need a gauge to screw onto the valve. It looks like a car tire valve stem.

Customer: replied 1 year ago.
I've noticed that. I will test the pressure tomorrow and then I'll let you know the result, thanks
Expert:  Charles replied 1 year ago.

Thanks