Yamaha four stroke 90 hp outboard problem. Any ideas and recommend a mechanic? Updated...

[Creedmoor]

Yamaha four stroke 90 hp outboard problem. Any ideas and recommend a mechanic? Updated...

I have a 10 year old Yamaha 90hp four stroke with a problem and was wondering if anyone had and ideas of what is causing it and any recommendations of mechanics.

I have never had any problems out of this motor before.

Today I put in on the Hiwassee at Hwy 58 and ran down to the TN river.

When I slowed down to an idle the motor quit and would not restart.

I waited a while for it to cool down and then tried several things and found that it would run at high RPMs but would not idle.

I managed to get it in gear at wide open throttle and ran back to the ramp but still would not run below about half throttle.

Not sure what is causing the problem but seems to be a fuel issue.

I ordered a fuel/water filter/separator and a fuel filter to see if that fixes the problem.

If that doesn't fix the problem I will likely have to take it somewhere.

Any ideas on what is causing it and also a good Yamaha mechanic?

Thanks!

Update:

I took it to Tom Taylor yesterday and he had it fixed this morning.

He figured out that it was an issue with the throttle position sensor.

He adjusted a small screw on the throttle body that adjusted the throttle linkage very slightly and it now starts and runs fine at all RPMs.

When I had it out on the river I didn't experiment with it much since I was mostly concerned about making it back to the ramp and loaded up before thunderstorm moved it.

Tom said that it would run at all RPMs but would die just as it got down to minimum idle.

He didn't have the equipment to do full diagnostics but I do believe that he found the problem.

I may swap out the throttle position sensor at some point. I'm going to take the boat out play with it some but not get too far away from the ramp until I am convinced it is ok.

Tom seemed like a good guy with a lot of experience and would recommend him. The only downside is that he does not have the equipment to run diagnostics on Yamahas.

One upside is that it didn't cost me very much for Tom's services.

Tom Taylor
423-435-1121
3950 TN Hwy 30 west
Decatur.

 

[jbh3]

Re: Yamaha four stroke 90 hp outboard problem. Any ideas and recommend a mechanic?

May also look at changing out the fuel lines (and primer bulb, if it has one) from the tank to the engine. Not sure where you're located, but Bunch Marine up in Harriman is a good shop.

 

[rsimms]

Re: Yamaha four stroke 90 hp outboard problem. Any ideas and recommend a mechanic?

Besides the primary fuel filter, most Yamaha's have what's called a "Micro Filter." It is basically like an aquarium airstone that filters out super fine material from your gas. If it gets clogged it takes high pressure (high rpm's) to force the gas through it. But low pressure (low rpm's) can't do it.

I can't tell you exactly where it's located but, but follow your fuel line under the cowl end-to-end and you should find it.

Exact scenario you describe happened to me on a previous Yamaha. Even mechanic didn't know about the micro filter until he called the factory to discuss my problem the THIRD time I took it back.

 

[Creedmoor]

Re: Yamaha four stroke 90 hp outboard problem. Any ideas and recommend a mechanic?

rsimms - 7/6/2022 10:36 AM

Besides the primary fuel filter, most Yamaha's have what's called a "Micro Filter." It is basically like an aquarium airstone that filters out super fine material from your gas. If it gets clogged it takes high pressure (high rpm's) to force the gas through it. But low pressure (low rpm's) can't do it.

I can't tell you exactly where it's located but, but follow your fuel line under the cowl end-to-end and you should find it.

Exact scenario you describe happened to me on a previous Yamaha. Even mechanic didn't know about the micro filter until he called the factory to discuss my problem the THIRD time I took it back.

Thanks for that tip, I'll research that.

 

[Creedmoor]

Re: Yamaha four stroke 90 hp outboard problem. Any ideas and recommend a mechanic?

jbh3 - 7/6/2022 9:06 AM

May also look at changing out the fuel lines (and primer bulb, if it has one) from the tank to the engine. Not sure where you're located, but Bunch Marine up in Harriman is a good shop.

The fuel line and bulb seem good but I do know that they can go bad.

Should have said that I am located near Harrison Bay.