1999 Yamaha 4 stroke F50TLRX running rich

[panasonic]

Who the hell is Rube Goldberg? Never mind I looked it up..never heard that saying before...but it is a good one!

[99yam40]

So, Rodbolt does that mean that he has to manually activate the choke at cold start(hit the switch)?

[rodbolt17]

plenty of info on this system.
it is overly engineered .
I like that.
I call it a rube-Goldberg system.
it was only used on the F and T 50's of the late 90's.
it is not quite a prime start yet not quite a full manual system.

[TownsendsFJR1300]

Pan send me your email address

Please post on the forum, I'd (and apparently 99Yam) would like to know how this system works as well.


I don't think it falls under Rodbolts "stupidly simple" systems... WAY OVER COMPLICATED..

[ChuckB1954]

Mr Boscoe because there is no information on the actual operation of this system, just how to test and adjust the different components. I am trying to figure out how this overly engineered start system works.

So when trying to start a dead cold engine, with key on, the choke solenoid is energized and the choke plates close....engine starts. After engine is started the "Electrothermo ram" is energized and after a period of time it allows the choke plates to open again.... this is done mechanically through linkages?

Once engine is warm enough to start on its own, without any enrichment, the "Thermo switch 2" prevents the choke solenoid and electrothermal ram to function?

But that makes no sense (thinking out loud) because the thermo switch 2 appears to be "normally open" and closes when warmed up.

You have anymore information on this?

Ran out of time to run the engine, but I did spin it over to see if the solenoid would activate. It did not. I will run it tonight.

[boscoe99]

Pan send me your email address

[panasonic]

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.

f50 choke.JPG


Mr Boscoe because there is no information on the actual operation of this system, just how to test and adjust the different components. I am trying to figure out how this overly engineered start system works.

So when trying to start a dead cold engine, with key on, the choke solenoid is energized and the choke plates close....engine starts. After engine is started the "Electrothermo ram" is energized and after a period of time it allows the choke plates to open again.... this is done mechanically through linkages?

Once engine is warm enough to start on its own, without any enrichment, the "Thermo switch 2" prevents the choke solenoid and electrothermal ram to function?

But that makes no sense (thinking out loud) because the thermo switch 2 appears to be "normally open" and closes when warmed up.

You have anymore information on this?

[panasonic]

……………………………………………………………………...

[99yam40]

Being called prime start, I would think it should be automatic operation.

Not many know about those F50 motor setups

[ChuckB1954]

Installed the missing parts on my motor (prime starter assy, solenoid coil) Took about 1/2 hour getting the plus lead from the solenoid armature connected to the carb linkage.

20190530_183402-small.JPG

Plugged everything in to the correct existing leads as per the wiring diagram:

20190530_184235-small.JPG
carb wiring.JPG

Thought by flipping the toggle on the controls, that the solenoid would react, but nothing happened.
20190530_185508-small.JPG

Had to quit for the night, but I am getting there. The blue wire and the green/white wire coming from the main harness is how both components get power. Maybe the prime starter is how it should be, but I would think that I should be able to work the choke solenoid from the toggle switch, although I could be completely wrong. The 703 controls are from the old C55TLRS 2 stroke motor that was on there. I need to check out the wiring diagram closer.

[ChuckB1954]

The parts should be in within a few days. I will let you know the results.

[TownsendsFJR1300]

Key West is a very good boat. My friend had one, a little larger than yours, decades ago...

You got a great deal...

[ChuckB1954]

You guys kill me with the prices on boats down there...I wouldn't get the used trailer for $1500 up here. Nice boat, how long is it?

He got some kinda deal. Pricing has gone wacko here too. I priced a new aluminum trailer couple years ago. $4200. Boat trailer is basically nothing, a rail job. Used horse trailer? $11000.
22 ft Sportsman Bay Boat? $68000 New. Sportsman mind you....
[/QUOTE]

A few of my friends are jealous and cannot believe the deal I got on this boat.

[ChuckB1954]

As all but carb #4 is NOT available anymore (and that one is over $400), I'd jump on that set. As long as they fit..

Heck you can part out your old carbs (I'd keep as spares) as you know they work to offset the $ of replacement ones. You still have the old motor you can part out too!

I'd probably leave your carb's on and just swap over the solenoids, etc....

Where abouts in Florida are you?

Thanks! I purchased that moments after posting the picture. I added up the cost of all the parts from Yamaha and saw I was well ahead. Not to mention there were many small pieces that were no longer available.

it's a long story on the two stroke engine that originally came off the boat. My friend who turned me on to this Key West boat had taken the engine and was going to repair it. It was beyond economical repair so he bought a powerhead somewhere that was in very good condition. He sold it to another friend but still they cannot get it running right. It is also missing some pieces. Only the previous owner's son knows what happened to the parts from both of these engines.

I currently reside in Loxahatchee Florida. I have another place in Inverness that I go to on the weekends. This boat will probably stay down here for now as I have a 12ft Jon Boat with an eight horse Yamaha on it up there. That little 12-foot is quite scary! Nowhere near as stable as that Key West boat!

[TownsendsFJR1300]

I Think I am going to bite the bullet and buy this now for $324.00.. all parts look to be there including the obsolete ones.. Plus many extra carb parts.. Am I crazy? I haven't even checked the compression yet..

As all but carb #4 is NOT available anymore (and that one is over $400), I'd jump on that set. As long as they fit..

Heck you can part out your old carbs (I'd keep as spares) as you know they work to offset the $ of replacement ones. You still have the old motor you can part out too!

I'd probably leave your carb's on and just swap over the solenoids, etc....

Where abouts in Florida are you?