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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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Have 25 hp Efi mercy this spring started running rough

Customer Question

Have 25 hp Efi mercy this spring started running rough intermittently like its stumbling.stumbles then runs fine happens at all speeds. Seems like the longer u run it the
Better it runs. Let it set for a week right back to the uneven running any ideas?
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.

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

When was the last time the engine ran correctly?

Does the alarm for the engine work?

Customer: replied 1 year ago.
Last summer we are up north so winters are long splashed it this spring problem showed up immediately. If by alarm u mean little red lite on front of motor and horn noise, yes I believe they work..why?
Expert:  Charles replied 1 year ago.

the horn more than the light, I was wondering if you were getting an alarm.

Have you check the oil and the spark plugs yet to see how they look?

Customer: replied 1 year ago.
Sorry for delay no horn..changed plugs..old ones looked normal..haven't checked oil level.i am confused
As to why it goes from stumble to perfect running..then back..over & over.2 was ago..stumbled a bit during
Warm up..then mostly perfect.almost seems like a fuel or choke thing
Expert:  Charles replied 1 year ago.

You can test the fuel pressure that is going to the fuel rail. A common gauge that can screw onto a schreader valve will work, as long as it can read atleast 40 PSI.