2007 115HP Optimax cold starting problems

[hubster951]

First off, I don't know much about Optimax motors and not that mechanically inclined. So, I have a 2007 Optimax 115HP. Serial number 1B492232. I bought this bass boat 3 years ago. The boat came from out of state, but the dealership sent me a video of the compression checks on all three cylinders and they were excellent. The motor had 37 hours on it and it has always run fine. I use it about 20 times a year. Probably has about 80-100 hours on it now. I put in some new oil about 8 months ago and used Penzoil xlf. It continued to run fine but over the last few months it is difficult to start when cold. It takes about 5-6 attempts before it starts and then it really smokes bad for a few seconds. It use to start up first crank. The motor runs fine at idle and speed, but has an occasional misfire I guess you would call it, but overall it is pretty smooth. It still will do about 43MPH top speed, which is what it would do when I got it, and when it didn't have any problems, so I think the compression is probably still very good. So once started it runs good, but after it sits for 15 minutes for more, it has the same cold starting problem. I'm assuming the penzoil xlf motor oil is no good and is causing carbon buildup on the air injectors, but I'm no mechanic and just guessing. I changed the spark plugs and air filter. The air filter had a black spot on it about the size of a quarter, I think where the intake tube is. I also added some quickleen before the last trip. But, I had the same cold starting problems the next trip with no improvement at all. I'm changing the fuel filter now, but it looks ok. There is some dark orangish colored granules/flakes at the bottom of the fuel filter housing which I've tried to suck out with a vacuum.

I did put some quickleen in before the last trip, but I only run about 3 miles each fishing trip.

Would it be worthwhile to have the motor decarbonized and can I do that myself. Any tips on how to do this? Would adding triple the amount of quickleen help remove carbon and deposit buildup on the air injectors? I read where one person had starting problems from carbon buildup on Optimax air injectors, but can't find any others with the same problem. I know little about these motors, but I thought I read where they have fuel injectors and separate air injectors. Maybe I'm wrong, but could my problem be carbon buildup on the air injectors.

Appreciate any help that can be given. I've cleaned and changed fuel injectors on my 115 Yamaha four stroke, but this optimax looks alot harder to do and I would probably just take it into the shop and pay the big bucks for labor here in southern California, if that was the problem. But, I'm thinking since it idles ok and runs ok (other than when cold) that it is not the fuel injectors.

Thanks for any help provided.

[EuropeanAM]

Definitely make sure you are keeping up with ALL recommended Annual Maintenance (that's every 364.99 days for most folks):

Recommended Annual Maintenance for Optimax Engines

Orange colored granules are likely degraded/deteriorated fuel line. Likely need to run through all of it:

FUEL LINES AND PERFORMANCE PROBLEMS

[hubster951]

Thank you. I appreciate it