Optimax 225 power loss

[r0b3rt]

Hi group, first time posting here, but not the first time around. I have learned a lot with previous post.

I'm making the post looking for some guidance on a issue that I currently have with one of my motors. The engine is an Optimax 225 0T997374.

• What the engine is doing?
  
  • After being out of the water for about a month, painting some parts and non engine related stuff, one of the engines loss power. When getting the boat to plane, the engine stays at around 3000rpm while the other is at 4000rpm. I can get the working one WOT to around 5500rpm while the problematic one WOT barely reach 4000rpm. I can get that engine pass 4000rpm if I remove load from it (trim up the motor).
  • Engine start with no issues, no alarms, no missfire at idle or while running.
  • When I'm at those rpms 3500-4000rpm, there is no hesitation or bog down of the engine, it stays at whatever rpm, but significantly lower than the other.
  • Engine haven't had any compressor failure.
  • Both engines are feed from the same fuel tank.
  • I noticed that the engine with the issue, has a higher voltage reading +\- 14.5V vs +\-13.5V of the working one while running.
  • No prop change or height adjustment has been made.
  
  
• What have I verified?
  
  • New Iridium sparkplugs, gaped to 0.38.
    
    • Tested after installing them, the issue continue.
    
    
  • Remove air injectors to clean and test them.
    
    • Air injectors were found with carbon build up at the tip.
    • When testing them, before cleaning, one of them was not flowing.
    • All 6 injectors were cleaned, tested and all of them now flows.
    • Re install them, issues continues without any improvement. I was expecting at least some improvement if not that the issue was resolved at that point.
    
    
  • Fuel injector removed and cleaned.
    
    • Fuel injectors were found to be clean when removed, no debris on the side feed strainer neither on the tip.
    • Haven't tested again after this.
    
    
  • VST removed to inspect high and low pressure pump strainers.
    
    • Both strainers were found clean and no debris on the VST.
    
    
  • Verified coils for breaks on the cables, but none has been found.
  • When removing Injectors and VST, no debris were found on the fuel rail neither on the hoses.
  
  
• What I'm pending to verify?
  
  • TPS/ TB Butterfly travel, ensure that it is opening 100%. (should have verify that first)
  • Compression test.

What else could I be missing here?Thanks.


Prop Exhaust.jpg Left prop is from the engine with issues
Air Injectors before.jpgAir injectors before cleaning
Air Injectors after.jpgAir injectors after cleaning & test

[JOE54]

compression test first if good then a cyl drop test while underway would determine non working cyl

[r0b3rt]

Update....

• Compression test was performed, 80psi-90psi result.
• Verified spark on all cylinders and all of them have spark.
• Changed the air injector that wasn't flowing before cleaning, to the other engine. Problem stood on the same engine and did not pass to the "good" one.

Could bad reeds would be a possibility for the loss of power?

[JOE54]

sure could , fuel inject swapped also ????

[r0b3rt]

Only the air injector that showed no flow before cleaning.

Fuel injectors were cleaned, but before cleaning, they did not have any debris on the strainers neither on the tip.

[JOE54]

which cyl is not contributing to power????? need to isolate non working cyl

[EuropeanAM]

+1 ^^^^^^

Cylinder Misfire Test while on the water, running at that engine's max RPM's would be the best way to narrow this down.

Record RPM drop for each cylinder.

Can be done on most suitable diagnostic tools.

[r0b3rt]

Thanks for the suggestions. I will verify the reeds and if the inspection outcome is good, proceed with the drop test.

Since I don't have a diagnostic tool, can I disconnect the cylinder from the coil signal cable instead of the sparkplug cable?
Don't want sparks jumping around.

[JOE54]

sure i guess you could but becareful if done while underway best if done electronically with diagnostic equipment but i understand

[massbays]

can be done @ a ramp boat strapped down to trailer.
in gear, some throttle on so you can definitely hear the cyl drop.
I can't imagine trying to do this @ 50mph across a lake.

[r0b3rt]

hahahaha, no it won't reach 50mph. It is a twin engine boat.
What I do is only accelerate WOT with a single engine.
Engine with the issue only reach up to 2,100rpm while the working one goes up to 4,500rpm.

I could try at the dock, but would be putting a lot of stress on the cleats.

[massbays]

twin engine using only 1 motor means you are about 6" overpitched.
A lot of stress on that one motor.
I like to give an assist by running 1 @ about 2000 rpm, and then full throttle the other.

[JOE54]

^^^^^^ +1 way over pitched if it's running correctly

[r0b3rt]

Would try it that way massbays. Make sense about the excess load on that engine. But that's the data that I have now to compare between both.
Would make the assignment during the weekend.

[JOE54]

report back with non working cyl location please

[r0b3rt]

Ok, I did the test this morning. All coils connected, rpm went up to 2700 -2900.
Disconnecting a coil, drop them to 2000-2200 rpm. Cylinder 4 disconnected, did not drop rpm.
Swapped coil and fuel injector.... cylinder 4 shows the same behavior. Didn't swap ior injector, I swapped last weekend with the other engine.

Now that the issue is narrowed down to cylinder 4, coil, air and fuel injector not being the issue. What else could be?

[massbays]

Now that you have a direction, back to basics on that cyl.
compression, fuel, ignition, timing.
opti fuel involves fuel injector, air injector,reed valve.

[r0b3rt]

Massbay.
I already swapped coil, air injector and fuel injector for that cylinder.
Before the test runs, I inspect the reeds but with a mirror I did not see any damage on them.

[JOE54]

spun sleeve

[r0b3rt]

I do notice, when inspecting the reeds, a little puddle of oil on the intake manifold. Would that be normal or be a sign of bad Reed?
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