1999 Yamaha 4 stroke F50TLRX running rich

[ChuckB1954]

Thanks for all the great info. I will address each post one at a time and provide some more pictures.

[99yam40]

I would be asking the people that sold it to you where the rest of the parts are

[TownsendsFJR1300]

Picture worth a thousand words. I was scratching my head looking at the parts diagram and was just going to see if I could get the info from the sevice manual to see how that works.

I guess those choke plates are not spring loaded open? Or that may have been part of the choke system that was removed also.

From his description the choke plates must be only partially closed as he can run it for awhile before fouling the plugs up.

Chuck....you need those parts on the engine to make it run properly as designed

Looks like the "solenoid coil works" has a large, pull spring below it.

With the direction of the fuel flow arrows, it appears the spring holds the choke butterflys open and the solenoid closes them when activated...

As noted, missing those parts, the choke butterfly can flop around, open and close at will...

[boscoe99]

Joe, send me your email address again plz.

[panasonic]

Picture worth a thousand words. I was scratching my head looking at the parts diagram and was just going to see if I could get the info from the sevice manual to see how that works.

I guess those choke plates are not spring loaded open? Or that may have been part of the choke system that was removed also.

From his description the choke plates must be only partially closed as he can run it for awhile before fouling the plugs up.

Chuck....you need those parts on the engine to make it run properly as designed

[boscoe99]

Greetings! I just found this forum and am a new member

I recently purchased the subject motor. It seems to start and run normally out of gear, but after running it under a load, the plugs become black and sooty.
It seems the linkage to the choke butterflies are activated any time I move the throttle. The only thing that linkage is connected to is the throttle linkage.
Seems like there is nothing keeping the choke from opening and closing on it's own.
I noticed when looking at the parts diagram that two solenoids are missing. Would these missing solenoids cause my engine to run rich by allowing the choke to open and close on it's own??

Picture of my engine with the empty solenoid bracket shown in the center of the picture. Also solenoids in question. #9 and #36 shown in the parts diagram.

Only one solenoid is used. Please help me understand how two are missing? Or are you saying that both the solenoid and the Prime Start thermoheater are not installed on the motor? #9 and #36 in your illustration?

[boscoe99]

[boscoe99]

A 1999 F50TLRX uses both a prime start assembly (thermoheater) and choke plates. The thermoheater in this model is causing the choke plates to open or close. It does not work like other PrimeStart components on other models. During the start the solenoid is energized and this also causes the choke plates to close.

Two strokes can have PrimeStart. Carbureted, EFI or HPDI.

Four strokes can have PrimeStart. Carbureted, EFI or Direct Injection.

A PrimeStart is not a PrimeStart is not a PrimeStart. It is a Yamaha term coined for automatic fuel enrichment. There are many ways and components involved to automatically provide fuel enrichment if and when needed.

[TownsendsFJR1300]

For everyone as well: https://www.boats.net/catalog/yamaha...arburetor-link

You SHOULD have Prime Start, for cold start up (enriches the mixture), part #9.

I believe, that part missing (missing) would cause a rich condition. Someone else will have to chime in to confirm..


Looking at your picture (not so clear), it appears you have choke butterfly linkages, is that correct???

It shouldn't per the parts site: https://www.boats.net/catalog/yamaha...lrx/carburetor

[ChuckB1954]

Greetings! I just found this forum and am a new member

I recently purchased the subject motor. It seems to start and run normally out of gear, but after running it under a load, the plugs become black and sooty.
It seems the linkage to the choke butterflies are activated any time I move the throttle. The only thing that linkage is connected to is the throttle linkage.
Seems like there is nothing keeping the choke from opening and closing on it's own.
I noticed when looking at the parts diagram that two solenoids are missing. Would these missing solenoids cause my engine to run rich by allowing the choke to open and close on it's own??

Picture of my engine with the empty solenoid bracket shown in the center of the picture. Also solenoids in question. #9 and #36 shown in the parts diagram.