Optimax problem number 1001

[rangerdan]

Yesterday, I did spark plugs test on all cylinders and discovered that cylinder 2 and 5 both misfired and eventually cut out completely. Today I replaced drive coil for 2 and 5, ignition coil also were replaced on 2 and 5 but didn't fix the problem. Checked all wires with multimeter and seems to be in working order. Brand new plugs and wires. Also, did ohms test on the new coils and within the spec. No fault code on DDT Any help or advice to what to look for next is greatly appreciated. One last thing, all cylinders fired up and idle perfectly in the morning but after 15 minutes or so of running (Doesn't matter if its idle or WOT), cylinder 2 and 5 begin to misfired and then cut off. Let the motor sit for a day or two, again started right up and ran fine again for another 15 minutes or so.

It is 2001 Optimax 150

List of new parts that I either recently put on or within a year or two.

New belt

Tracker Valve

Air and fuel injectors sent in to have professionally cleaned and serviced

Battery 1000A

Fuel and Air pressure tested within spec, 90 psi fuel and 80 psi air

Compression 120 plus or minus 5 on all cylinders

Crank position sensor

replaced low pressure fuel pump last fall

Poppet valve and themostats

Brand new main tank with new fuel line

Paid a shop in CA to have ECM tested and no fault found.

MAP sensor

Thank You in advance

Alternator

[GLF]

I found this post and it might help you out.

[KJ pluggin]

Welcome to GLF Dan, good luck with the Optimax.

[ALLEYES]

I had injector problems with my 225 Opti. Ended up blowing the motor. I think it was #5 that went. Rebuilt now and running good.

[rangerdan]

Thank you for your response. I swaped out the coil , ignition coil, spark plug wire and plug. I performed continuity check from ECM to the drive coil ( 4 pins 2 pins ), continuity check from drive coil to ignition coil. I also switched wiring from 1-3 drive coil to 2-5 drive coil hoping that if ECM is bad my 1-3 cylinders would fail but that was not the case , 2-5 cylinders failed again. I did ohms test and found the reading within spec ( Service Manual ). I have had a bad experience with a local Merc service rep where I live. I have back ground in outboard motor, worked for my dad who was a part owner of a boat dealer. Currently serving in the Army as Diesel mech for over 18 years. The merc mech is telling me it would be best to repower ( Assuming because I told him it has over 1800 hrs on the motor) and purchase one of his used motor, this is without even looking at my motor. I paid another dealer for an hour worth of work to have my motor hooked up to DDT but that didn't help any because no fault or error were found. This weekend I will swap out 2 and 5 air and injector with 1 and 3 and see if 1 and 3 will fail?? Running out of idea. BTW, talked to Merc directly from the factory in Fond Du lac and I'll quotes him " Make sure I have 1000Amp battery and use only Merc parts" REALLY ???

[ALLEYES]

Merc is well aware of the problems with the Optimax back in the late 90's early 00's. A good friend had one on his bass boat and it failed also.

They do have that problem fixed now.

[rangerdan]

Alleyes, do you know what was the problem with you buddy's bass boat?

[ALLEYES]

Same as mine. Injector problems, causes the cylinder to fail. Take some time and research it. Opti's are well known for it.

[rangerdan]

I basically gave up working on it and my boat is now at the dealership. Received a phone call from a mechanic and he think its the harness but not ruling out ECM completely. DDT showed number 2 failing but not the number 5. Nothing showing up for injectors. I do have a good feeling about this mechanic as he seems to really want to be sure before throwing parts on ( Harness $638, ECM $1200 plus Labor). How is this work as far as labor cost? Is he going to charge me 8 hours for troubleshooting? and possibly more on Monday? Thanks

[ALLEYES]

I suppose he sure could.....

Here in Michigan they are required to give a written estimate. If they go over it they contact you and make sure it is OK. If not, you do not have to pay more than the estimate.

[Sea Eagle]

I had a similar problem with my 2003 150 Optimax this spring that the dealer could not find.

The boat would not get up on plane and I had lost about 10 mph from my top end.

Nothing showed up on any error codes. They said I needed new plugs and a fuel filter and wanted an arm and a leg to do that, so I purchased the parts on line and replaced them myself.

However that did not solve the problem, so back to the dealer I went. This time they found a bad coil on my #5 cyl. This did fix the problem for a couple of trips, then it returned.

Only this time, the boat cut out on me as I was running in and I received an alarm. I turned the boat off and checked the error message and it said that I had a bad coil. I restarted the boat and it ran fine. This time the dealer had an error code to work with and they said that Mercury told them to replace all of the coils.

I checked it out when it was done and noticed that the new coils are a different part number. I bet they had a design issue with the original coils.

This did fix my problem for good and the motor has run fine for the last three months.

Not sure if this helps - good luck.

[rangerdan]

Sea eagle,

Finally after mechanic consulted with Mercury Master tech, he came out and they came to conclusion that it's wiring harness and the ECM that needed to be replaced. I replaced both parts and the boat is now running great again. I guess the positive side to this is now my motor has a lot of new parts on it. BTW, this dealership only charged me 1.5 hour of labor for troubleshooting, parts replaced etc.