2005 F90 Stalls at Idle/Ocassional Hard Shifting

[FLCoyote]

About three fishing trips ago my Yamaha F90, stalled at idle a couple of times. The next time I went it stalled five or six times. I replaced the fuel water seperator and the under cowling fuel filter and on my last trip it started surging between 6 and 9 hundred RPMs and then would shut off. It starts right back up and runs great at all speeds above idle. From what I could tell the fuel is fine. I always treat it with marine Stabil. There wasn't any water in the under cowling filter. I could blow thru that filter without any effort. After emptying the fuel bowl/cyinder the squeeze bulb refilled the bowl in about three pumps so I don't think the fuel/water separator is bad. I replaced the spark plugs last Sunday and ran the engine on the hose for about 20 minutes without any problems. It ran at 1000 the entire 20 minutes, so I don't know if the engine had time to warm up. All of my problems were after running for over 30 minutes at 4000-5000. The spark plugs I took out had clean gaps but were black and sooty at the base and they were very easy to remove. I had them put in by a marine mechanic about 70/80 hours ago and now I wonder if he forgot to torque them and if my problem was caused by blowby from loose plugs? Along with this problem and at about the same time the shifter became much harder to operate on an intermittent basis. About every seven or eight times I shift I have to put a lot more pressure on the controls. I had this checked out by a marine mechanic and he said the controls and lower unit were fine and it was shifting correctly. On my last trip it only happened twice. Any thoughts on this would be appreciated. My owners manual states that the idle can only be adjusted with the boat in the water and that it should be done by a Yamaha dealer. Any shortcuts or advice on this?

Thank You
FLCoyote

[mitch]

give your isc (iac) valve a clean remove and clean with some carb cleaner one other thing with the hard shifting check your shift switch is working ok you will probably have to connect it to yds to make sure.

[FLCoyote]

Mitch, Thank you very much for your reply. My skill level is very basic. Please advise me where the ISC (IAC) valve is located and general removal instructions. Does it have a cover? Is it part of another assembly? I'd rather take a shot at cleaning it myself as my local dealer is $85 an hour and the boat would be tied up for 3 to 5 days. Planning to go Snapper fishing Friday if I can get this worked out.

FLCoyote

[mitch]

number 10 on this break down

Yamaha Outboard Parts 2005 F90TJRD INTAKE 1 Diagram

just make sure the o ring is ok there is a little button in side just give that a good clean in carb cleaner do not pull it apart just give it a good clean

Do not remove number 6 as you need YDS to set IT up PROPERLY OR AT LEAST A WORKSHOP MANUAL

[FLCoyote]

Mitch, Thank you very much. I'll give it a try tomorrow.

FLCoyote

[FLCoyote]

Mitch, This afternoon I took the cowling off, removed the flywheel cover, unbolted the air cleaner and took the two mounting screws out of the IAC. I found the O'Ring, no problem. Then couldn't find/see the little button anywhere. You advised not taking the IAC apart. In any event tje IAC was held together with two TROX screws that has a raised pin in the middle of them. I've got a set of TROX screwdrivers, but none with a pin hole in the middle of the screwdriver head. I put everything back together until I know what to do next. Is the button that needs to be cleaned inside the IAC. Is there a special screwdriver to take the IAC apart. Please advise as soon as you see this as I've still got tomorrow to get it fixed without canceling the Friday fishing trip. An oh by the way it the square washer on the flywheel cover got dropped inside when I took it loose and I haven't found it yet. I hope it didn't drop into the lower unit! Can it do any damage or is it just going to be kicking around inside the cowling? I really appreciate your assistance. I can change oil, filters and spark plugs, but after that I'm still finding my way.

[FLCoyote]

YamahaF90 IgnitionSwitch Multiple Problems Solved

I replaced the ignition switch on my 2005 F90 last Friday Afternoon. I took the boat on a 60 mile fishing trip in the Gulf on Saturday. Not only was the switch fixed, the hard shifting, surging between 6 and 9 hundred RPM's at idle before stalling, clicking starter solenoid before starting, and clicking tilt and trim solenoid before engaging all cleared up and the motor was flawless all day, plus we limited out on big Red Snapper and one keeper Gag Grouper. I talked with a neighbor that works for Yamaha on ATV's and Motorcycles and he said he wasn't surprised that the switch was the source of all of those problems and that he sees similar problems on a daily basis. The only problem we had all day was that the livewell was overflowing into the bilge and the automatic switch on the bilge pump wasn't working. When we discovered that the boat was slowing down due to a bilge full of water we turned the pump on manually and it pumped out fine. I don't know of any way to test the automatic switch other than filling the bilge with water? Anyway plan to just replace it this week. The switch is a Rule and the pump is separate. Thanks to all who commented
.FLCoyote

[melaatik]

how to clean iac properly?

Mitch, should the two torx screws in IAC assembly be opened in order to clean the valve properly? You adviced not to pull apart the assembly.

I´am thinking whether to open IAC completely (by opening these to torxs) and is it difficult to put the parts back.

[TownsendsFJR1300]

Mitch, should the two torx screws in IAC assembly be opened in order to clean the valve properly? You adviced not to pull apart the assembly.

I´am thinking whether to open IAC completely (by opening these to torxs) and is it difficult to put the parts back.

You know thats a 4 year old thread???

[rodbolt17]

that valve is NOT serviceable.
that's why it has tamper proof torx heads.
key switch failures on Yamaha marine stuff is incredibly rare.
don't know about the motor sports side.
in about 20 years I think I have seen 3 switch failures in a FACTORY Yamaha switch.

[melaatik]

cleaning

that valve is NOT serviceable.
that's why it has tamper proof torx heads.
key switch failures on Yamaha marine stuff is incredibly rare.
don't know about the motor sports side.
in about 20 years I think I have seen 3 switch failures in a FACTORY Yamaha switch.

Thank you rodbolt.

Lets continue about cleaning of IAC in the thread "How to clean IAC of 4-stroke Yamaha Outboard"

[melaatik]

Idle surging despite of cleaning IAC

Despite I cleaned IAC as advised, my F100 still has rough idle. It surges between 600 and 700 rpm and the running sound is not even at all. This surging is emphasized especially when I slow down to neutral idle from the plane. However, when the engine is hot enough and it has had time to run at idle, the running is almost perfect and this surging disappears.

These are already checked:
- spark plugs replaced
- fuel filter in the engine replaced
- water separator filter replaced
- gas tank cleaned and new non-ethanol gas added (there was not water or contamination at all in the tank or in the filters)
- thermostat checked, opens as specified
- IAC cleaned (not tested yet if heats during running)
- Fuel injector additive just added to gas (effect unsure at the moment)

Engine is -06, has only 80 hours (has been without using for few seasons) and not been used in salt water at all.

Any tips what to check next?

[TownsendsFJR1300]

I don't have a specific answer for you at this point however, I would personally run the engine some more and give that fuel additive a chance to work.


May I ask what product your running in the fuel?

[rodbolt17]

I am somewhat stupid.
yet I have to ask.
why?

why would any fuel additive help clean an ISC?

[TownsendsFJR1300]

I am somewhat stupid.
yet I have to ask.
why?

why would any fuel additive help clean an ISC?

You know your not stupid as well as everyone (myself included) on this forum, howver there are other products that do indeed work even thou you don't believe so. I'm new to Yamaha outboards (this is my first), but not to engines. I grew up on Yamaha motorcycles, have repaired carbs, transmissions, etc since 1970.

I know your not big on fuel additives (short of marine Stabil).

I have had very different experiances on all engines using different products. Stabil, being a bad experiance (not marine stabil) with a mower aluminum carb varnishing up even with using it within a month). I personally wouldn't go near Stabil..

As for the fuel system cleaner, my suggestion was to clean the entire FUEL SYSTEM, not the ISC. He already cleaned the ISC per your directions.


Just curious, do you believe Yamaha's "Ringfree" for instance, is a useless product??

Previously mentioned was K100 (which I do know the contents of it). I can say from personal experiance, (just over two years) that product and non-ethnol fuel has any water (that used to show up in any fuel purged from my boats 50 gallon fuel system) has ridded the water, or at least, (as designed) suspended it so it could be burned out with the regular operation.
I've NEVER drained or removed my built in 50 gallon fuel tank since new, (1997) even living in Humid and hot, SW Floirida.

I've personally used straight SEAFOAM in a 500cc twin, Kawasaki motorcycle with totally clogged, twin carbs. The bike sat, with fuel in it, no stabilizer for over two years under a tarp, in a car port, again in humid SW Florida.
The bike was given to my friend and I offered to pull the carbs and clean them. He didn't want to do this for some reason, I suggested the Seafoam. WE drained the carbs of nasty fuel and poured straight Seafoam down the fuel line into the float bowls and let it sit.
Several hours later, we drained the Seafoam, hooked up another fuel tank(inside of the original was rusted from water, half full, etc) and filled it with fresh fuel.
Cranked it and it fired and ran on one cylinder initially.
Kept it running, the 2nd cylinder eventually starting firing. Lots of smoke (4 stroke), but within a couple of minutes, it was idleing on BOTH CYLINDERs, running, accelerating, etc. I personally didn't think it work on this particular bike as its issues were SO BAD.
If you believe me or saw it, I think you'd have a very diffent opinion of that product. I knew it worked, but that well, really surprised me.

But to each his own...