225 opti issues

[CATmech945]

I'm working on a 225 opti for a buddy of mine and I'm kinda stumped. This boat has twins and the stb engine has all kinds of power and the port, well..........not so much. The boat will get up on plane and run but the stb engine drags the port one up to r.p.m. At full throttle the port turns maybe 4500 and the stb is a tick over 5k. The engine doesn't sound like it's missing but it just doesn't have any balls. I changed the primary and secondary fuel filters thinking they were stopped up, but it didn't change anything. I need to run a compression check on it but does anyone else have any experience with these engines. I'm sort of wondering if maybe it's a weak air pump.....but I don't even know what the pressure is supposed to be initially. If anyone could stop my head from spinning and point it in the correct direction, I would greatly appreciate it. Thanks in advance.

Aaron

[Capt Matt]

When my last motor lost rpm at the top end it was a coil and simply not firing on all cylinders
Capt Matt

[CATmech945]

Ahhh, Capt. Matt. I figured you'd be the one to reply. I've actually been meaning to P.M. you for some time now but just keep forgetting to do so. I wanted to ask you about the optimax motors anyways being that you make money with one. I'm considering purcasing one for my personal boat. Anyways, I'll touch back on that in a p.m.
My evinrude did the same thing when a coil quit but you could hear the miss when the engine was running while on the trailer. This engine seems to be running smooth both in the water and out. It just won't turn up.......it doesn't have the two stroke snap. Dare I say, it's acting like an underpowered boat with a four stroke. I plan on doing a compression check and pulling the coil wires with the engine running and see what it does. I just wasn't sure how much emphasis I should put on the air pump. The guy doesn't maintain this thing all to well. I think the work I'm doing on it is the most love it's had in awhile. Thanks for your input.

Aaron

[GoneFission]

Cat:  I'm not sure if the Optis have the same ignition system, but most V6 Mercs have 2 switchbox units, each firing 3 cylinders.  It sounds like you have a bad switchbox.  Sometimes the switchbox will fire at idle, but won't work at higher RPM.  Usually a coil fails outright.  

To see if it's a coil, just disconnect one spark plug lead at a time.  You know which cylinder is problematic if you disconnect one and it makes no difference in idle. Once you isolate the cylinder, you can see if it's a bad wire, loose connection, or coil.  

Hope this helps - good luck!

[fitz73222]

Cat:  I'm not sure if the Optis have the same ignition system, but most V6 Mercs have 2 switchbox units, each firing 3 cylinders.  It sounds like you have a bad switchbox.  Sometimes the switchbox will fire at idle, but won't work at higher RPM.  Usually a coil fails outright.  

To see if it's a coil, just disconnect one spark plug lead at a time.  You know which cylinder is problematic if you disconnect one and it makes no difference in idle. Once you isolate the cylinder, you can see if it's a bad wire, loose connection, or coil.  

Hope this helps - good luck!

"Our" ignition systems were completely redesigned in '97 with a new CDI / Coil module as one assembly per cylinder, so bye bye to the switchbox design. I'm not up to speed on OPTi's and troubleshooting them beyond normal diagnostic protocol.

[wingtime]

Keep to the basics check compression and spark on each cylinder...  but it sounds like your on that track already.

[gran398]

This may sound simplistic...but sometimes crazy stuff happens...are they propped exactly the same?

[Capt Matt]

If the air pump goes it will have a death rattle or lock up solid like the motor has blown up. Take it from someone who has replaced at least 8 of them. I now know the warning noise on the compressor thats going to let loose. The compressor usually overheats from restricted water flow and the bearings go.  They don't loose rpm at top end they just rattle until they totally quit. One sign that its getting close to time for a new compressor too is when the motor starts it revs real high before coming back down to idle.
My guess is still a coil, the motor will be smooth until higher rpm. On a V6 hot rod like a 225 you won't notice its only running on 5 cylinders until higher rpm. Opti's always have that one of a kind sound to them too. I can tell one in the dark from a mile away
Once you go black you will never go back
Capt Matt

[GoneFission]

"Our" ignition systems were completely redesigned in '97 with a new CDI / Coil module as one assembly per cylinder, so bye bye to the switchbox design. I'm not up to speed on OPTi's and troubleshooting them beyond normal diagnostic protocol.

I hate it when that happens.   :evil:

[fitz73222]

"Our" ignition systems were completely redesigned in '97 with a new CDI / Coil module as one assembly per cylinder, so bye bye to the switchbox design. I'm not up to speed on OPTi's and troubleshooting them beyond normal diagnostic protocol.

I hate it when that happens.   :evil:

They'll have to pry my cold dead fingers from my carbureted Mercs!

[CATmech945]

Thanks for all the tips guys. I checked the compression the other day and all were around 120 psi so all good there. I didn't have much time so I didn't get a chance to isolate the cylinder by pulling the plug wires. Wingtime.....I checked the props and they are the same. Counter rotating of course but they are the same. Good call though, we usually over complicate things when it's something rather simple. Capt. Matt, thank you for the info on some of the symptoms for the air pump. I don't have much experience with these engines so I was scratching my head. I'll check the plugs next and let you all know what I find. It's hard to hear if there's any difference in sound between the engines while running but I don't hear any difference other than a lack in r.p.m. when I try to just run the port one up. We'll see. Thanks again for all the help. I'll post back soon with some findings. Maybe this will help someone else out someday.

Aaron

[RickK]

Thanks for posting back!
Keep us in the loop.

[CATmech945]

FINALLY!!! I figured it out, haha. I put all new plugs in it, same thing, so I pulled the wires and put a plug in one wire at a time to check for a bad wire...all good. I started the engine up and set it around 1100 r.p.m. and started unplugging injectors one at a time. The two center cylinders and the two lower cylinders would shut the engine down when I unplugged them. When I unplugged the top ones......no change. The right side injector would stop clicking and then start again when plugged back in, but it didn't change the way the engine was running. The solenoid is making noise but nothing is happening. The top left one did absolutely nothing. It didn't click, change the engine, nothing. I think it's safe to say that the top two injectors are shot. Now my next question. Does anyone know where the best place to get new injectors would be?? I work in the diesel world mainly so injectors are usually remanufactured or servicable so forgive me if this is a dumb question. I didn't know if these were servicable or not. Again, thanks for all the replies and help. It's a good group here.

Aaron