1996 250 dies after choke is off***baffled**

[jerseysportfisher]

Hello,

the motor ran great 2 seasons ago, had a baby so it was fogged and drained.

finally getting to it, she would spiratically start. Completely disasembled all 6 one barrel carbs. each soaked in "old" carb cleaner acid based for at least 30 minutes. I blew the carbs out with compressed air. recleaned them with carb cleaner spray can through all jets and passage ways. Reassembled. cleaned and blew out fuel line tree. soaked and cleaned fuel screen. soaked and cleaned one way check valve. fuel pumps were replaced 2 years ago. Test and have adequet pressure and do not leak. reconnected all line. have 6 gal test tank. primed started, ran like a champ untill the chokes came off. When cranking and i stick my hand over to throats at a time fuel comes out and motor will stutter. all carbs produce fuel when hand is over throat. I was thinking my idle circuit were clogged, but i noticed a gold can on top of the fuel line tree , i assume its a fpr. could this be the culprit ?

 

[rodbolt]

Re: 1996 250 dies after choke is off***baffled**

ok
the 96 250 yamaha had NO chokes.
instead it uses 6 solinoids and an electric pump for fuel enrichment for cold starting, pump runs anytime the key is on.
solinoids are controled by the ECU based on various signals from various sensors. did you replace the solinoid orings when reassembling?
if the orings leak it runs incredibly rich to not at all.
a quick test with the diagnostic test lamp will show if anything the ECU monitors has failed, otherwise continue finding your fuel or link and sync issue.

 

[jerseysportfisher]

Re: 1996 250 dies after choke is off***baffled**

If any one is interested in the future....


the problem was the one way valve between the on board screen and the fuel pump. It was sticking intermittenly, how i found this is when i pulled the fuel lines every thing was bone dry the including the pumps. A quick and easy test i found for this is prime the bulb, you will see fuel sloshing around in the onboard screen "clear plastic bowl", the bulb would then get hard as a rock, with a lot extra force the ball valve release allowing the bowls in the carbs to be filled, sound like air brakes releasing with the psssshhhhhh. Its always something stupid..... dont over look the obvious like i did the first time with a quick shot of compressed air. inspect..inspect...inspect, hope this helps someone else.

 

[rodbolt]

Re: 1996 250 dies after choke is off***baffled**

read the tech bullitens, ditch the checkvalve.
they have killed a lot of good motors.
its very rare to see electronics issues on that motor, fuel issues are quite common and with E-10 are getting worse and sometimes bizzare.
but remember, that motor has NO choke, be careful how you deal with it if you dont understand how and why each sensor works with the engine and ECU or you WILL post about a popped piston.
just a warning.
seen it to many times.
go to your nearest yamaha dealer and ask to see all the tech bullitens that pertain to a 3.1L carbed engine.

 

[jerseysportfisher]

Re: 1996 250 dies after choke is off***baffled**

rodbolt appreciate the help, one, you said ditch the one way valve, correct me if im wrong but the fuel pumps is a plunger with half @zz stainless flaps trying to act as reeeds, this prevents back flow of fuel ??????? 2. what do you recomend as a laquer coating " anti corrisive coating" i can spray back onto the outsides of the carbs......


thanks

Jim

 

[jerseysportfisher]

Re: 1996 250 dies after choke is off***baffled**

whats your opinion on stabil ?

 

[rodbolt]

Re: 1996 250 dies after choke is off***baffled**

for aide in anti-corrosion Boeshield t-9 or fluid film, no way to clean a carb from the outside.
stabil is good, if the fuel is fresh it will aide in the preservation for about 5 months, after that DO NOT run it in that 2 stroke.
bad fuel kills two strokes very handily.
I know its costly but it just is what it is.
I dont break them but I do have roughly 30 years fixing them.
the check valve was simply there to aide in fuel drainback while sitting, was a good idea that did not work and was later ditched by yamaha.
keep good T-stats and filters, a bad T-stat can take out #6 piston.

 

[jerseysportfisher]

Re: 1996 250 dies after choke is off***baffled**

so just take the valve out of the equation ? What i meant was a spray from the outside to prevent corrosion.