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Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3383
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I have an Optimax 90 2007 and the boat only goes up to about

Customer Question

I have an Optimax 90 2007 and the boat only goes up to about 2600 rpm, with no warning alarms going off. Last month put in a new oil reservoir tank and new direct injector, because of a very similar issue(but at that time the warning alarm was going off). ran fine for a month now this....any suggestions?
Submitted: 7 months ago.
Category: Boat
Expert:  Charles replied 7 months ago.

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

What alarm were you getting last month?

Which spark plug did you install?

Do you have a multimeter to do some testing?

Customer: replied 7 months ago.
It was the four beep in a minute alarm and they hooked it up to a scope and said they had error codes for those two things that they switched out. We change all three spark plugs but that was only after it wouldn't run past 2600 RPM. No I do not have a multi meter to do not have a multimeter to do testing
Expert:  Charles replied 7 months ago.

Without a meter, we are rather limited on what we can test. There is one thing that you can try, but you will need to get the boat in the water to find out of it worked, Locate part 29 in the diagram. It is under the oil tank, unplug it from the engine harness, then run the boat and see if you can get over 2600 RPM, if you can, you will need to replace that switch.

http://www.boats.net/parts/search/Merc2/Mercury/90%20DFI%20%283%20CYL.%29%281.5L%29/1B227000%20THRU%201B417701/Exhaust%20Plate/parts.html

Customer: replied 7 months ago.
Ok I will try it. Thx
Expert:  Charles replied 7 months ago.

Let me know how it turns out.

Customer: replied 7 months ago.
Will do
Expert:  Charles replied 7 months ago.

Thanks

Customer: replied 7 months ago.
Good morning Charles I tried for about an hour yesterday I cannot locate that switch do I have to remove the oil tank?
Expert:  Charles replied 7 months ago.

It is mounted directly under the oil tank, but the wires run out the stbd side to the main harness.

Customer: replied 7 months ago.
Ok thanks I will try disconnecting it tonight and let you know.
Expert:  Charles replied 7 months ago.

Sounds good, Talk to you then.

Customer: replied 7 months ago.
Hi Charles I looked everywhere and I cannot find anything that looks like that part that has the two black wires in it the switch. The only thing I can find has one black and white wire on it I attached a picture but I don't think I'm gonna be able to find the switch and I search for two hours in the Mercruiser diagrams and can't find anything that shows the location for the switch. The boat also cuts out now on a regular basis when I idol or when I kick it in gear randomly the engine will die but then starts right back up. Any suggestions i'm where to find the location of the switch in a diagram that I can get my bearings
Expert:  Charles replied 7 months ago.

remove that side skirt, it is much easier to get at then.

Customer: replied 7 months ago.
Ok will do. Thx
Expert:  Charles replied 7 months ago.

You will be able to see the top of the shift linkage then. The switch is right there.

Customer: replied 7 months ago.
Ok cool
Expert:  Charles replied 7 months ago.

Talk to you then

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