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Dominick
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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I have a 2008 Larson Bowrider with a 240hp Mercruiser IO

Customer Question

I have a 2008 Larson Bowrider with a 240hp Mercruiser IO Engine starts fine. Idles fine. Starts out fine. When I hit the throttle it wants to die out. Doesn't stall, just dies out. After it warms up it runs just fine. No issues. Only happens when motor is cold. What's the problem
Submitted: 8 months ago.
Category: Boat
Expert:  Jason replied 8 months ago.

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

All Mercruisers are cataloged by serial number, can I get that number so I know exactly which engine you have.

Customer: replied 8 months ago.

Don't have that on me. The boat is two hours away at the lake.

Expert:  Jason replied 8 months ago.

Mercruiser does not make a 240 hp engine. What is this, is it V6 or V8? Is it carbureted or fuel injected?

Customer: replied 8 months ago.

5.0L

Expert:  Jason replied 8 months ago.

Carbureted or fuel injected?

Customer: replied 8 months ago.

That I don't know. I am guessing fuel injected as I have not seen the carburator

Expert:  Jason replied 8 months ago.

You really need to find out what you have first. This isn't going to work if I don't know which engine you have.

Customer: replied 8 months ago.

Unfortunately I don't have the information at hand.

For this purpose assume it is a 5.0 L 220hp fuel injected I/O Mercruiser

Year 2008. Runs perfectly fine when warm but starting out loses power when applying full throttle. I can nurse it to full throttle and after running 5 minutes goes to full throttle just fine.

..and the problem is?????

Expert:  Jason replied 8 months ago.

Did you want to get it and get back to me? Or did you want to call it quits?

Customer: replied 8 months ago.

I thought I gave you what you were looking for. I gave you the engine type

Expert:  Tan replied 8 months ago.

Hello. My name is Tan.

The only thing I can think of off hand is a bad ECT (engine control temperature) sensor. If it thinks the enginbe is cold the engine will want to stall on throttle up. What kind of engine temperature are you running at? You could have a sticking thermostat that won't allow the engine to get up to temperature in a normal amount of time. This could also be a failing ECT telling the ECM the engine is cold when it actually is up to temperature.

If this is a carbureted engine a choke that is staying closed to long will cause the engine to run rich till choke completely opens.

On the fuel injected engine you will have to have the engine scanned to find the problem as this will set a code in most cases.

On the carburetred engine you have to take the boat out with the flame arrestor off and watch the choke plate.

Does this make sense?

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