2000 Optimax 225 Idle Bouncing around 2400 rpm

[NewFisher]

Hi there friends,

Just joined because I bought my first boat that I will use to go after smallmouths and other species in Lake St. Clair and The Great Lakes. I brought it home this weekend but I am more familiar with the OMC Sterndrives of my father's boat then these outboards. I did a compression check on the motors before buying it but I did forget to open up the throttle but with the throttles closed my cylinders were all around 90psi.

My port engine serial 0T090477.

The throttle/cable is super hard to push on this engine so I am not sure if it is problem. There is a brand new throttle cable in box laying in the boat must be for this engine. This engine fires right up and idles at around 23-2600rpm but it has no beep codes and otherwise seems to run good. I briefly read that maybe I should the air pressure & fuel pressure and make sure there is a 10psi difference. Should I start there or look at the throttle cable first?

[EuropeanAM]

Engine should idle at 565-650 RPM's. It should never idle at 2300-2600 RPM's (either there is a problem in the fuel system OR the throttle cable is not returning to the idle position).

[NewFisher]

I will take the time to learn and check the pressures this week then. I knew idle should be much lower, but my other engine was idling at 900 so I thought maybe 900 was normal but now I know that engine is slightly high too. After I check pressure I'll report back my findings. Thanks Don!

[NewFisher]

Hi there friends,

Just joined because I bought my first boat that I will use to go after smallmouths and other species in Lake St. Clair and The Great Lakes. I brought it home this weekend but I am more familiar with the OMC Sterndrives of my father's boat then these outboards. I did a compression check on the motors before buying it but I did forget to open up the throttle but with the throttles closed my cylinders were all around 90psi.

My port engine serial 0T090477.

The throttle/cable is super hard to push on this engine so I am not sure if it is problem. There is a brand new throttle cable in box laying in the boat must be for this engine. This engine fires right up and idles at around 23-2600rpm but it has no beep codes and otherwise seems to run good. I briefly read that maybe I should the air pressure & fuel pressure and make sure there is a 10psi difference. Should I start there or look at the throttle cable first?

Don is there a write up somewhere with pictures on checking the fuel system? I quickly checked the stickys but didn't see one but I'm at work so I could only quickly check.

[bass.man65]

I sure hope you don't put this engine in gear off a 2300 rpm idle.

[EuropeanAM]

No- those types of things are most commonly found in the Factory Service Manual (perhaps the best investment you can make if you're going to do your own service).

DEFINITELY don't attempt to shift the engine if it's not AT IDLE.

[NewFisher]

I sure hope you don't put this engine in gear off a 2300 rpm idle.

Well I actually had to just once. I had seven days in my purchase contract to be able to contest the lower unit, any signs of low compression or a cracked block and of course it did give a slight grind but otherwise went into gear just fine.

So I had a couple of Mercury Optimax manuals at my disposal but nothing seemed exact for my engine. Then one of the Rinda guys pointed out that my engine serial numbers show as 3.0L EFI on the Mercury parts search engine although my outboards have the "Saltwater Optimax name on the cowl. Does that sound right?

I have found other 2000 Pro Line 30 Walk Arounds to have these same motors as OEM fitment so the engines being the same year as the hull I am sure they are the original outboards and not a repower.

[EuropeanAM]

How about you snap a picture of the front and back of your powerhead... I have a sneaky suspicion that the serial numbers are right, but the cowlings are wrong.

[NewFisher]

mercury3.jpgmercury2.JPGmercury plug.JPG Don these are the pics I sent Rinda to help determine what connector I needed, I'll take new ones you want as soon as I get home for you.

[EuropeanAM]

Definitely an EFI.

[NewFisher]

Since we determined it's an EFI, does that mean the throttle cable is most likely the culprit for my extremely high idle then Don since I don't have to worry about air pressure for DFI?

[EuropeanAM]

Throttle cable, bleed line sticking in one of the butterflies behind intake, improperly set/synchronized throttle roller/cam would be the more common causes.

[NewFisher]

The cable being extremely stiff makes me think it has to do with that but I will investigate all this. As far as my engine trimming, it did go back mostly down but it barely moved at a very slow pace and as soon as I let go of the button it wouldn't move again. Does not matter if if I use the throttle button or the button on the outboard itself. That sound like trim motor?

[EuropeanAM]

Maybe, Maybe NOT. Really needs to be isolated and checked separate of the switches and relays before condemning the trim motor.