2002 Yamaha F50 prime start / choke

[nmuir999]

Hi all. Newbie on the forum.

I have a new-to-me 13’ rendova with 2002 F50 Yamaha. Question is about the carbs.

It is very hard to start so I wanted to check the carbs are ok. All is fine once warmed up. I understand that F50 are very cold-blooded but this seems far wore than that.


I see that older F50’s have chokes. My year is listed as having prime starter so I assume that is what I should be looking at. However my carbs do not match the online parts diagrams, not can I see anything that matches the older chokes or the newer prime starter components. I checked what I could find online for later 90’s through 2005, thinking it might be carbs from the wrong year.


The number is F50TLHA, which is listed as a 2002. (from what I read the H means tiller steering, whereas mine is not, but I don’t think that impacts anything)

I attach a photo.

Can anyone shed any light on the prime starter for this specific model?

[Pikey Dave]

Originally Posted by nmuir999

Attachment 101678

Hi all. Newbie on the forum.

I have a new-to-me 13’ rendova with 2002 F50 Yamaha. Question is about the carbs.

It is very hard to start so I wanted to check the carbs are ok. All is fine once warmed up. I understand that F50 are very cold-blooded but this seems far wore than that.


I see that older F50’s have chokes. My year is listed as having prime starter so I assume that is what I should be looking at. However my carbs do not match the online parts diagrams, not can I see anything that matches the older chokes or the newer prime starter components. I checked what I could find online for later 90’s through 2005, thinking it might be carbs from the wrong year.


The number is F50TLHA, which is listed as a 2002. (from what I read the H means tiller steering, whereas mine is not, but I don’t think that impacts anything)

I attach a photo.

Can anyone shed any light on the prime starter for this specific model?

Hi & welcome to Ribnet.
Firstly I know bugger all about your engine, so take anything I say with a big pinch o'salt. The Prime starter could be an electronic choke that is operated by a solenoid. If your engine started life as a tiller steer & has been converted to remotes, then the electrical connection for the choke from the helm might be missing. Just a thought & as I said, could be complete bo11ox. There's more discussion here: 2003 Yamaha F50 Four Stroke - Help! - Walleye Message Central

[nmuir999]

Thanks Dave.

What I don't get is there is no obvious (to me at least!) prime starter mechanism on the carbs.

(should be on carbs 1 and 3 according to some parts listings Yamaha F50tlra/t50tlra 2002 Carburetor - schematic partsfiche)

I have seen posting on the different means to control them - some via key and some automatic when the ignition is on. Trick for me is there seems to be nothing to control! (ie no primer starter)

Thanks in advance for any help anyone can provide!

[Boats&Outboards]

Here it is - number 34

Its a white plastic solenoid with two wires running from it (Black earth and Blue from memory).


I've an entire 4 carb setup here from a used F50 engine if your interested in buying the whole rig, message me


Peter @ Boatsandoutboards4sale
07930 421007
www.BoatsandOutboards4Sale.co.uk

[Pikey Dave]

Originally Posted by Boats&Outboards

Here it is - number 34

Its a white plastic solenoid with two wires running from it (Black earth and Blue from memory).
Attachment 101688

I've an entire 4 carb setup here from a used F50 engine if your interested in buying the whole rig, message me


Peter @ Boatsandoutboards4sale
07930 421007
www.BoatsandOutboards4Sale.co.uk

Hmm! looking at the OPs original pic, there's a blue wire disappearing down the opposite side of the carb block, could be it.

[matt h]

As mentioned above by the Guys, Its item 34...

If i remember the choke is a wax stat type thing.. if you just connect it up you wont see any movement for ages. and it works in the opposite way.e;g when off, it retracts.

When the engine is cold and ign is off.... not in use, the plunger is in it fully retracted state.e;g choke is on...
When ign is on and engine starts....The wax stat moves VERY slowly (as the wax heats due to internal windings) starts to push the plunger out e'g to stop excess fuel going through..as the engine warms

If yours isnt working then I would suggest taking the solenoid type thing off and cleaning it all through.
then wire it up with your original wires on the engine and watch it move (after 5mins) it only moves Millimetres.

[matt h]

Oh and the other thing.. its NOT on all three. Just one OR possibly two and the other 2 solenoid looking things are possibly the fuel shut off valves (to prevent overrun and emission's n shit)

OR

it could be you have two wax type choke things!! I really cannot remember as Im getting old.

I had the same on my F40 and when I cleaned out the wax stats it started perfectly and came off choke within 4-5 mins
On the 3 pot engines Im sure you have one place on cylinder 1
and on the four pots engines you have 2.

[nmuir999]

Thanks guys. Yes, discovered on the back side of carb # 1 - a bit buried under the top cover.

Thanks for the help and comments. Now onto diagnosing it! I saw some other threads on how to test it, how slow it is, how it doesn't move much etc. I'll post up whether it makes the difference, though might be after Christmas now!

Have a good holiday everyone.

[willfinch36]

I hope that you don't mind me bumping an old thread, but I am having similar issue(s) with my 2004 F50, after some thoughts...

When cold the engine struggles to start, and when you try to accelerate it cuts the power, although after getting it warmed up it really struggles to hit WOT. After about 30 seconds or so the power will suddenly kick in and it will run fine.

Engine recently serviced with fresh fuel and carbs/jets all cleaned & fresh fuel,but that made 0 difference at all. I assume if it was an electrical problem then the issue would be more consistent regardless of temp/rev range?

The choke have been taken out and cleaned out. Maybe I will need to have a look at the solenoids.

Another thing is, there appears to be water coming out of the middle exhaust hole - not sure if this is normal for this 2004 50AET model.

Thanks,

Will

[matt h]

Take out the solenoid and look at the brass needle. A clue would be that there is corrosion around the base.. if there is you will need to unblock the hole to which the pin locates. These carbs will block easily if any manky fuel gets it..

[willfinch36]

Originally Posted by matt h

Take out the solenoid and look at the brass needle. A clue would be that there is corrosion around the base.. if there is you will need to unblock the hole to which the pin locates. These carbs will block easily if any manky fuel gets it..

No Corrosion or anything - the carbs have been fully cleaned out.

Engine struggles to start when cold, and until its warmed up will try and cut out when you go for WOT.

But once warmed up it appears ok, unless you come off the throttle and then WOT it again, will hesitate and finally get up to max RPM. Wonder if its fuel pump related? Tried different fuel can/line/new fuel filter.

If you squeeze the bulb while accelerating that makes no difference either.

[beamishken]

The problem is most likely carb related id strip all the carbs to the bare bones and put them all in an ultrasonic bath for a few cycles its most likely old fuel dried in a tiny hole and its very hard to clear

[beamishken]

The problem is most likely carb related id strip all the carbs to the bare bones and put them all in an ultrasonic bath for a few cycles its most likely old fuel dried in a tiny hole and its very hard to clear

[beamishken]

The problem is most likely carb related id strip all the carbs to the bare bones and put them all in an ultrasonic bath for a few cycles its most likely old fuel dried in a tiny hole and its very hard to clear

[matt h]

As above.. the carbs were not the best. very small holes everywhere and even an ultrasonic wont do them. as said above, strip them again and re check.. also do a check the wax choke valve.
wire it up to a 12v supply and it will take 2 mins or so to move if I remember.

it should slowly stretch out.and plug the fuel supply in the main body... it may be stuck out in which case the choke valve is not working...

[willfinch36]

Originally Posted by matt h

As above.. the carbs were not the best. very small holes everywhere and even an ultrasonic wont do them. as said above, strip them again and re check.. also do a check the wax choke valve.
wire it up to a 12v supply and it will take 2 mins or so to move if I remember.

it should slowly stretch out.and plug the fuel supply in the main body... it may be stuck out in which case the choke valve is not working...

Hooked it up to a 12v supply and they work so I guess will have to strip the carb down again.
Thanks

[matt h]

Good. Concentrate on the hole where the needle goes through...
Took me 4-5 attemps ,, each time I thought id done it , I hadn’t

[beamishken]

Originally Posted by matt h

Good. Concentrate on the hole where the needle goes through...
Took me 4-5 attemps ,, each time I thought id done it , I hadn’t

Yep it took me 3 or 4 goes with a 25 carb in a ultrasonic bath
Which was the best 40 quid ive spent on ebay forcages

[willfinch36]

Originally Posted by beamishken

Yep it took me 3 or 4 goes with a 25 carb in a ultrasonic bath
Which was the best 40 quid ive spent on ebay forcages

Thanks Guys - Will report back with (any) results!

[matt h]

Basically the fuel supply isn't getting to the engine, good luck