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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10966
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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Customer Question

Hi tan
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hello Jorge.

The alarm sounding with a constant tone is most likely over heat alarm. When the engine over heats the engine goes into Guardian mode not allowing the engine to use all power reducing the rpms.

Now this can also be low water pressure or low oil pressure. When was the last time you had the water pump serviced?

Could I get the engine serial number please?

Customer: replied 1 year ago.
Water pump and raw water pump both are ne OEM out of the box.
Some one told me about the water presure sensor, but this engine does not have one.
Expert:  Tan replied 1 year ago.

Could I get the engine serial number please? I need to know if this engine is carbureted, Throttle Body Injection or Multi Port Injection?

Customer: replied 1 year ago.
By the way the alarm sound intermitent
But solid every 5 to 7 seconds.
Expert:  Tan replied 1 year ago.

Intermittent alarm is a failing sensor or gear lube bottle fluid level low or the sender in the bottle is bad. Be sure the gear lube bottle is full. If full disconnect one of the leads to the bottle. Does alarm quit? If the alarm doesn't quit then you have a sensor failure. This will require the use of a Scan tool or DDT to find failing sensor.

Now as for the loss of power this is possibly a fuel starvation issue. There are 2 ways to test for fuel starvation run engine on a different fuel source or connect a vacuum gauge in the fuel supply line to the engine. Run the boat if it runs better on the other fuel source then you have a fuel restriction in the boat side fuel system. If you run using the vacuum gauge the gauge should never exceed 2" of vacuum. If the gauge exceeds 2" of vacuum then you have a fuel restriction.

Do these checks and post back with findings.

Customer: replied 1 year ago.
Ok. I wil get back with answers or more questions.
Thanks and good night.
Expert:  Tan replied 1 year ago.

Ok your welcome and have a good night yourself. Thank you.....Tan

Customer: replied 1 year ago.
Hi tan.
Since the last time we talk i replace all the injectors due to one of them was not working at all. Put new and the engine wont start now
Seems like the injectors are not working.
I took off one of the fire plugs and this one was completed dry.
Any idea ??
Expert:  Tan replied 1 year ago.

Hello. Have you checked the fuel pressure on the fuel rail? Do you hear the fuel pump run when you turn the key on?

Customer: replied 1 year ago.
When open he itnition switch the pump star and stop as normal. The funny thing is that minutes before was working.
The fuel rail has fuel but not tested the pressure yet. It used to be at 40 psi.
Expert:  Tan replied 1 year ago.

Ok we have to verify the fuel pressure as it won't run unless the fuel pressure is up to spec. Since the plug was dry this kinda of tells us we have no fuel pressure.

Customer: replied 1 year ago.
Im doing it right now
Expert:  Tan replied 1 year ago.

Ok. Can you post the engine serial number also?

Customer: replied 1 year ago.
Just checked the pressure. Its at 40-43 psi
Is hat ok ??
Expert:  Tan replied 1 year ago.

Fuel pressure is good. Do you have spark?

Customer: replied 1 year ago.
No spark. Just realized the mecanic was chequing compression on the cylinders and left disconected the coil.
Tomorrow i have a sea trial to check hiws is performing when under demand of power.
Thaks so much for the hint.
Tomorrow i let u know how it went.
Expert:  Tan replied 1 year ago.

Ok great glad it was something simple. Keep me posted.

Thank you......Tan

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