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Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 14299
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I have a 2012 F150 with 500 hours on it. Rpm are dropping

Customer Question

Hello. I have a 2012 F150 with 500 hours on it. Rpm are dropping and max speed was only 11mph when we came in yesterday. When I disengage the prop at the throttle I can get super high rpms.
Any ideas? Thanks!
Submitted: 1 year ago.
Category: Boat
Expert:  Jason replied 1 year ago.

Hello my name is ***** ***** am I speaking with?

There are lots of things it can be, and the engine needs some testing and troubleshooting in order to figure out the issue. It could be something very simple, such as clogged fuel filters or bad gas. Or something more complicated, like a fuel injection issue. What kinds of questions did you have for me, and what were you looking to do?

Customer: replied 1 year ago.
Hi. Thanks. I was hoping something might stand out to u as the problem.
Since it runs high rpm with prop disengaged I was kinda ruling out bad fuel. I use a lot of fuel here and it's never been an issue at this fuel dock.
I'm reading online about the switch that drops the motor to two cylinders, it definitely feels like that big loss of power. I was hoping to get an idea on what to replace on my own if west marine has the part. Not easy on Sunday of Labor Day weekend.
Thanks, Stephen
Expert:  Jason replied 1 year ago.

Hi Stephen

Since it runs high rpm with prop disengaged I was kinda ruling out bad fuel.

It would run at high rpm in neutral with a blown piston or no spark on certain cylinders. When in neutral there is no load, and the engine is simply spinning it's own weight, about 150 lbs of pistons and crankshaft. But when in gear it is under load, and has to push a 3000+lb boat. Those are 2 completely different scenarios.

West marine won't have anything for this engine outside of maybe a filter.

Where testing begins is testing compression, spark output, fuel pressure when under load. If nothing stands out, then run it on another fuel supply and hook up the scan tool. Between those 5 things something will stand out at that point to at least get one pointed in the right direction. That is what needs to be done. Is any of that things you can do on your own?

Expert:  Jason replied 1 year ago.

Hi Stephen. I looks like you read my reply and logged off. Did you have any further questions on the issue?

Expert:  Jason replied 1 year ago.

Good morning, just checking in. Any progress?

Expert:  Jason replied 1 year ago.

Hello, just checking in. The website has charged you but no rating has been put through yet in order to credit me for helping you out. Did you have any further questions on the issue?

Thanks,

Jason

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