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2003' Mercury optimax 175hp

A

akair

New member
I am having problems starting the engine cold, the engine will try and turn over and then beep. I already took it to a mechanic and $900 dollars later got ripped off for nothin. I can get the engine to start, after it starts there is a considerable lag time until the fuel can catch up to the power settings. I am going to point my finger at the fuel pump, but not sure. I read a couple of other posts about fuel problems. I know that it is nothing from the fuel tank, fuel/water sep, and inline filter. Is there something I should be looking for to indicate that the pump is not working when I am on step and cruising at 3800 rpm's. Because there seems to be no glitch after the boat gets to cruise speed. Maybe there is a sort of syphine that takes effect after the fuel starts to flow.
 
Re: 03' Mercury optimax 175hp

This motor is near impossible to troubleshoot without having it in front of you.

The continuous beep after it fails to start is most probably the guardian just telling you that the oil pump is not running (which makes sense since the motor is not running but the key is still in the "on" position).

Technology wise it makes the engine in a new car look like something that was built in the dark ages.

You have two fuel pumps (one conventional, one electric), a vapour separator, a fuel/air rail which is compressor driven and balanced by a tracker valve. A water cooled return fuel line - any of which could be clogged, toasted etc.

How old are the spark plugs? The lifespan of a sparkplug in an Opti is somewhat less than 100 hours with many needing replacement after 50 hours. Opti's eat sparkplugs for breakfast - a byproduct of the particular direct injection design used.

If they are more than a season old I would start with them (yes, they are about 15 bucks a piece retail - one of the joys of owning a "space age" contraption).

If that doesn't help then find a good "Merc certified" shop with a tech that is skilled in Opti's - they are not a normal 2 stroke and a 4 stroke dude won't have a clue...
 
Re: 03' Mercury optimax 175hp

I replaced the spark plugs every spring before I take it out, aws well as most of the other normal maintenence fuel/water seperator, etc. Were can a find a manual for the Opti motors?
 
Re: 03' Mercury optimax 175hp

I am not aware of an aftermarket manual for them and since they are a somewhat "specialized" motor I would cough the 80 bucks at a Merc dealer and get a factory service manual.

Sorry, I don't have the Merc part number, but the dealer can find in short order. My newest Opti manual is for the 2002 model year. Between 1999 and 2004 they "tweaked" these motors quite a bit working the bugs out and some things did change.

Because of that, even if Seloc's has an Opti manual you still be far better off with a "year specific" Opti service manual..
 
Re: 03' Mercury optimax 175hp

Sounds like a fuel or air pressure problem, you will need the mercury marine fuel/air pressure gague kit to test the pressure's. There is a fuel tracker valve and air pressure valve that keeps 10 psi between the fuel and air pressure's to keep the engine running correctly if there is not 10 psi between them the motor will run like a dog
 
Re: 03' Mercury optimax 175hp

Are you saying that while the engine is running there is a constant 10psi on the fuel line or is that after shutdown there is a constant pressure on the pump so that it is able to pick up fuel quickly. The problem is with the start up while the engine is running it purs like a kitten.
 
Re: 03' Mercury optimax 175hp

What im saying is that you will have to have 80 psi of air pressure and 90 psi of fuel pressure for your engine to run and start up easy. To diagnose optimax engine's you will need alot of mercury marine special tools. The first thing i would do is plug your engine into the diagnostic computer to monitor whats happening on start up, if all is normal there i would be checking the fuel and air pressure's.
 
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