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**boscoe99** · 11-22-2014, 03:28 PM

A 2004 Yamaha 90 two stroke does not have a choke plate or choke linkage. I wonder what it is that you are seeing. This might be why your manual is not mentioning it.

You can't compare one brand of motor to another brand. Hell, it is dangerous to try and compare one Yamaha model to another Yamaha model.

That motor has a fuel enrichment device that automatically provides extra fuel to the motor when the motor is cold. Once the motor is started and warms up it automatically provides less and less additional fuel.

There is a three position lever on the carburetor that is for (1) automatic operation, (2) manual fuel enrichment and (3) no fuel enrichment. The owners manual shows the position of the lever for each of the three functions. Have you verified that the lever is in the automatic position?

Have you thought about reading the owner's manual?

**99yam40** · 11-22-2014, 05:24 PM

Here is a place you need to bookmark so you can find and read the owners manuals Yamaha offers for free, but cannot download or print out.
Owners Manuals | Yamaha Outboards

If you have choke plates and linkage that is not hooked to anything some one has been swapping parts on the motor

**tuna5589** · 11-23-2014, 11:48 AM

Thanks for the replys. The engine is set up for manual choking. It has choke plates and linkage on the sides of the carbs, but the linkage isn't hooked up to work. The center carb does not have a electrothermal enrichment valve, all three carbs are the same, plus no additional hoses or electrial lines are attached to them. The person I purchased it from when asked about method for starting said to just move the throttle forward 3 times, similiar to pumping the gas petal in a car. This however won't do anything because the carbs don't have an accelerator pump.
The chokes need to be hooked up, has anyone ever seen this on this motor? Is it even possible to do?

**boscoe99** · 11-23-2014, 12:12 PM

What is the complete model identity please? Engine serial number would be even better. And a photo of the choke plate would be even better.

Here are the two Yamaha motors offered in 2004, one being a 90 HP two stroke and the other being an F90 four stroke. Non depict a choke mechanism.

I have never heard of any Yamaha offering a model with both a prime start device and a choke plate. Rodbolt, what do you know about this? I am open to learning something new. With Yamaha you can never tell.

Maybe someone changed the original configuration. If so, it is your job to put it back like it was when it left the factory. Given that I don't know what was done there is no advice I can offer as to how to correct it. Other than for you to follow the parts catalog to reinstall all of the original parts.

**rodbolt17** · 11-23-2014, 01:02 PM

the C85 and the 90 hp until about 1991 used a choke plate.
92 and up the c, B and 90 HP used prime start.
without a model number you either have a very old 90 or a franken motor.

**tuna5589** · 11-23-2014, 01:11 PM

The info on the motor tag is: 90 TLRC 6H1 L 1015424 P. I bought it from the 2nd owner who has owned it for several years and has not done any replacement of parts. Other then the starting problem the motor runs like a clock. This sounds like a problems I have with my truck, I must have the only truck that has a different emergency brake system on it that is not adjustable.

**rodbolt17** · 11-23-2014, 01:52 PM

have you actually had the airbox off????
you either have a franken motor or its prime start.
look at the top of the block, port side just aft of the flywheel.
if it has a crank position sensor it is post 1991 and is prime start.

if NO sensor its a pre 1991 powerhead on a newer mid section.

**boscoe99** · 11-23-2014, 02:29 PM

Your motor does not have and has never had a choke plate or choke mechanism.Unless some fool put different carburetors on it. Which I doubt.

Here is what you number 2 carburetor looks like.

It might be worth your while to inspect the fuel enrichment over ride lever. It should normally be in the full counter clockwise position. If the same fool that tried to install carbs with a choke messed with the red lever that might be part of your problem.

Now keep in mind that the motor is 10 years old. When was the last time the carburetors were cleaned and adjusted? Maybe when the chokes were added?

It is explained in the owner's manual. Here is a snippet.

**tuna5589** · 11-23-2014, 04:02 PM

Yes I have had the air box off. I have pictures but just have to figure out how to attach them. First it doesn't have a crank position sensor, and your comment that it could have had the power head replaced is valid, so I check that out. I found on top of the motor block on top of where the coolant comes into the motor a sticker with the motor serial number on it. This would seem to me that its the original block. I had also noticed that on the air box it has diagram about the emergency starter valve but didn't know what it was about until your attachment boscoe99, however there is not one on the motor anyplace. It does have choke plates and linkage on it and I can't imagine any reason anyone would change out the carbs and add the linkage and then not provide any way to make them work.

**99yam40** · 11-23-2014, 04:12 PM

apparently they had no clue of what they were doing if they did not make it work.

**rodbolt17** · 11-23-2014, 04:18 PM

you have a franken motor.
Yamaha never placed ID on the motor.
ALL 90 hp 2 strokes from 1992 and up had a crank position sensor.
well all that were imported to the US market.
so we are back to a franken motor.
why or who frankenstiened it who knows.
but frankenstiened it is.
the C85 and C 90 and 90 motors from 84 to 91 did NOT use a CPS and DID use choke plates.
the C90 and B 90 and standard 90 hp motors from 1992 on DID use a CPS and did NOT use choke plates. the CPS is a two wire sensor one blue/red the other blue/white.
pictures would help.

**boscoe99** · 11-23-2014, 04:44 PM

Originally posted by rodbolt17 View Post

you have a franken motor.
Yamaha never placed ID on the motor.
ALL 90 hp 2 strokes from 1992 and up had a crank position sensor.
well all that were imported to the US market.
so we are back to a franken motor.
why or who frankenstiened it who knows.
but frankenstiened it is.
the C85 and C 90 and 90 motors from 84 to 91 did NOT use a CPS and DID use choke plates.
the C90 and B 90 and standard 90 hp motors from 1992 on DID use a CPS and did NOT use choke plates. the CPS is a two wire sensor one blue/red the other blue/white.
pictures would help.

Methinks you have forgotten about the round sticker that provides the serial numbers that form part of the PID. The one on the block itself, usually in the vicinity of the starter motor.

**tuna5589** · 11-23-2014, 05:15 PM

I could send pix's but can't figure out how to do. If it is an earlier motor how were the choke plates hooked up to operate on them and couldn't this be done?

**rodbolt17** · 11-23-2014, 05:48 PM

never saw a disc that would id the powerhead to a specific year.
merc and OMC did but typically not Yamaha for some reason.

in any case the carb setup is NOT 2004.

the intake and carbs will physically fit but the 04 cowl had no hole for manual choke and I don't think the holes for the choke solinoid were drilled and tapped . I think the boss is there.

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2004 90hp hard starting

2004 90hp hard starting

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