f225 starts but don't dare turn her off!!!

[TownsendsFJR1300]

I'm not sure what two rollers your referring to but if its the belt tensioner Part #22, it shouldn't be making any noise/buzz; If that's suspect, its critical and should be checked for any slop, roughness spinning, etc.

2002 F225TXRA Yamaha Outboard VALVE Diagram and Parts

One member just had one fail about 3 weeks ago.


Re-reading your post, are the two larger cam gears what your referring to? And its NOT the tensioner?

[cmitchell2]

#18 Yes they have a slight hum at idle that sounds smooth so I think its normal. I can compare to other engine. May take ecu off bad engine and put on good one and see if it does same problem. Will be at boat all day if any suggestion from anybody. Thanks

[TownsendsFJR1300]

#18 Yes they have a slight hum at idle that sounds smooth so I think its normal. I can compare to other engine. May take ecu off bad engine and put on good one and see if it does same problem. Will be at boat all day if any suggestion from anybody. Thanks

#18 is just the cam gear, no bearing to go foul under there..

[cmitchell2]

Update

Took boat out. I inched the throttle up very slowly and the engine didn't shut off. I reached 3200 rpm but that was it. If I pushed for more she bogged down until I pulled back throttle and she would kick back in. When I idled again after a few minutes she would stop running. She runs rougher than the other engine as well. I have read about this pulling back the throttle and engine stops bogging so I'm going to research that condition again. By the way VST filter is new.

[rodbolt17]

still sounds like low rail pressure or clogged injectors.
both easy to test.
careful swapping ECU's its very possible if an electrical or device failure took out an ECU it will do it twice.
always easier to trouble shoot than randomly chunk swapped parts.
tech induced failure are rather expensive typically.
then I have to find the tech induced issue and the original issue.

[rodbolt17]

you are aware that in less time it takes for 3 pages of posting and about the price of a set of plugs you could have told us what the rail pressure is when it fails.

[cmitchell2]

Rodbolt you are absolutely correct. Sorry for the long thread but I am learning alot about my engines. The owner of the marina asked me if I had clocked in the other day. I will put fuel pressure gauge on and try to rev up at the dock. If rail pressure doesn't hold steady then we can assume my high pressure pump isn't working properly?

[rodbolt17]

assume.
ass out of U and ME.
assume NOTHING.
it works OR it does not.
the engine ECU ASSUMES way to freaking much.
it either is or it is NOT.
30 min tops to tell you if the hull is already in the water.

[cmitchell2]

Rodbolt, I paid a tech to hook up computer to my engine and got no codes. He said I have no vacuum (27"-29") at idle when it should be 15" at idle.The idle air control is showing 100% and the idle control is good because we swapped it to my other engine and it tested fine on that engine. The plugs are powder black with carbon and engine runs rough. The fuel pressure is also good at 45lbs. Any thoughts jump out at you?

[rodbolt17]

first thought is find a real tech.
running you should see a barometric pressure of around 30"Hg and a map pressure around 12"Hg.
that 100 % request on the ISC means the ecu sees a problem and is trying to increase the idle speed.

[cmitchell2]

first thought is find a real tech.
running you should see a barometric pressure of around 30"Hg and a map pressure around 12"Hg.
that 100 % request on the ISC means the ecu sees a problem and is trying to increase the idle speed.

What might cause the ecu to think it needs to request 100% ISC?

[rodbolt17]

bad spark plug, clogged injector, loss of spark, anything that the ECU DOES NOT monitor that would affect engine idle speed.
that's why is CALLED an ISC.
stands for Idle Speed Stabilizer.
the further it is opened the more idle air is allowed and the faster the engine idles.
spark is electronically con*****ed,
fuel is electronically con*****ed AIR is mechanically controle ABOVE idle speeds.
at Idle speed air is electronically con*****ed via the ISC.
that's why its constanly hunting on engine RPM at idle.
most all EFI motors hunt whether two or 4 stroke,boats,cars,trucks and yes even outboard,inboard and stern drives with EFI.

its also why EFI starts at a fast idle then calms down.
that rattle you hear,or should hear, at engine shut down is the ISC resetting for the next start cycle.

as for the cams, remember you have 2 cam CHAINS with tensioners that need periodic inspection and maint.