F90 Yamaha 4 Stroke EFI 2006 Rebuild

[msuspartan1994]

I purchased a 2006 Yamaha F90TLR EFI 4 Stroke with 25' Pontoon, The Engine had thrown a Rod from being overheating prior to my purchase so I replaced it with a new short block from Yamaha I have just started breaking it in. The Head also needed a little work at the machine shop with the valves on #2 cylinder and eliminating any wrapage.

Now for my question....
The rebuilt engine has plenty of power and overall seems okay when underway, however the engine seems to "Lobe", like a car would with a high performance cam shaft in neutral. It is like the engine ECM is compensating for something for a second or two and then returning to normal for a few seconds. Rough Idle..... Any help would be appreciated.

 

[99yam40]

Re: F90 Yamaha 4 Stroke EFI 2006 Rebuild

Have you hooked it up to computer to see what it shows?
These modern motors have lots of computer info just like cars.

Not sure if overheat would throw a rod

 

[msuspartan1994]

Re: F90 Yamaha 4 Stroke EFI 2006 Rebuild

Have you hooked it up to computer to see what it shows?
These modern motors have lots of computer info just like cars.

Not sure if overheat would throw a rod

Thanks - I have not tried the a computer yet because I dont have the program and cables to hook it up. I just wanted to make sure I check all the obvious things before bringing it in for service at the marina. I feel like they sometimes just replace parts until they find the correct one.