2007 225 Mercury Optimax Pro XS Sputtering Under Load

[bobby.leejr]

Engine: Jan 2007 Mercury Optimax Pro XS
Serial: 1B458912

Problem: Spitting and sputtering under load. When I load the boat onto the trailer it sputters and almost dies. On take off it will sputter and act like a vehicle does when it runs out of gas.

Two weeks ago, I took my new to me boat to the local Mercury mechanic to have the air and fuel injectors cleaned because I read that is good maintenance and upkeep. They called me that evening and informed me that I had a fuel leak and would need the diaphragm and tracker valve replaced. They also had to replace the spark plugs because they fouled those. I went ahead and said fix it to the tune of $1200.

I took the boat straight out and it was sputtering under load. Not horrible, so I thought maybe I have bad gas from the previous owner in the portside tank. So, I switched to the Starboard tank with fresh fuel that I put in and still sputtering under load. I fished for a few hours hoping the bad fuel would run through. Then I tried another trip and still the same problem.

I took the boat back to the mechanic and they told me today that they drained the fuel, cleaned the spark plugs, put a new O-ring on one of the fuel injectors, and replaced a cracked O-ring on the VST. Still the problem is not fixed. They said the fuel is at 90lbs and the air is at 80lbs. They are going to replace some plate tomorrow that I cannot remember the name of and see if that fixes it.

Can anyone give me some advice as to what it could be? The boat ran perfectly fine the first time I took it to them.

[lpugh]

Pressures too low for a proxs motor should be about 95 & 109

[JOE54]

does REED PLATE in compressor sound right , sir i smell a R A T in this situation and he aint dead , your boat ran perfect and now it dont , and you dont clean IRIDIUM spark plugs , advice they screwed up something in the rails probly , refund and leave seek another qualified technician very familiar with OPTIMAX engines ....... you asked .... good luck JOE

[bobby.leejr]

Yes, I believe reed plate was what they said. Supposed to replace it this morning, I am waiting to hear back if it worked or not.

[JOE54]

and yours was running perfect ,,,, hmmmmm

[EuropeanAM]

and yours was running perfect ,,,, hmmmmm

That engine did have a compressor replaced... and could very well have been subject to the reed bulletin because of that. Of course the warranty on that is long gone.

Agree he needs someone that actually knows what the pressures should be (for starters).

[bobby.leejr]

Update: They did borrow a reed plate and put it on. Then took it to the lake and it fixed the problem. I am sorry I was unclear in the previous post, but they did say the air and fuel compression was low. It does appear that the reed plate was the source of the problem. I will update when I get the boat back and confirm.

[EuropeanAM]

I'd say give 'em a break this time if that's the fix. Not much they would have done to cause a broken compressor reed, and odds are relatively high that it happened due to soft reed material.

[bobby.leejr]

I agree with EuropeanAM. I believe they are decent fellas and trying to help me. They are not charging me for all the time spent troubleshooting. Just the replacement reed plate and time spent on it. Just bad timing on reed plate being bad and the previous work.

[JOE54]

hope all is well and problem is solved

[bobby.leejr]

Update: Got the boat back and took it out. Still doing the same thing. I pulled three of the spark plugs and they are all black and look fouled. Now I am in for almost $1800 and still sputtering under load. What could be fouling the plugs?

[JOE54]

#3 i stand by what i said ,,, which 3 specifically cyl numbers please

[bobby.leejr]

I pulled all all six spark plugs, and they are all carbon fouled. I cleaned them best I could with carb cleaner and a toothbrush and tried again with the same result. I ordered all new plugs, but I need to figure out what is fouling them before wasting another set.

[bobby.leejr]

https://www.youtube.com/channel/UC1L...mr3l2k5nTCXTSA

I uploaded videos for anyone willing to help me. Thank you all.

The boat runs good except for between idle and take off.

[bobby.leejr]

Spark Plugs.jpg

[JOE54]

are you getting any fuel in air side of system , checked air Schrader valve

[EuropeanAM]

How long was that specific set of plugs in the engine? If you do any amount of idling, they're likely going to look like that.

[74mako]

Just watched your video, sounds kinda similar to mine. Starts great, idles great, after 1200 RPMs its bucking and surging unless I gun it but it wont hit any higher than 3K. Will yours go full RPM?

[bobby.leejr]

Update: They pulled the injectors and said the bad fuel must have clogged a few of them up. They cleaned the injectors again and the boat seems to be running good, knock on wood!!! 74mako it would get to about 5100-5300 but topped out about 53-54 mph. Now it hits about 5400 and tops out about 64mph.

[EuropeanAM]

Interesting... glad you're up and running.