2000 Yamaha 150 SX150TXRY - No Start

[AnotherBoat11]

Ran perfect until this problem
I have 38psi at high pressure pump at key on
I have spark and new plugs
Cranks but will not fire up
If I spray fuel to intakes will start and run till turned off & fuel pressure holds while running
If I turn it off it will then restart and run
If it sets over night back to no start
Open for any ideas & THANKS

[99yam40]

I know little about that motor, but is 38 the spec for key on fuel pressure?
have you cleaned the vst , injectors,screens/filters since it has a problem with getting fuel to start?

I though the injectors did some extra firing to get extra fuel for start up.
may need to see if they are doing what they are suppose to do.

hopefully Rodbolt will throw so light on what all could be a problem with that no start

[AnotherBoat11]

35psi per book
VST clean screen on pump new
Pulling injectors now
Per a tech at a local shop - said it sounds like a "enrichment" problem
Told him to explain to this old pollock what that means - said dirty injectors
Said get enough thru to run after I spray fuel for start up but not enough on a cold start
Make since to me but then again - a old pollock

[pstephens46]

CPostis left us awhile back. He lived for the X Motor. Maybe Rod can help. Hate to have to call him at home....

[TownsendsFJR1300]

Once it starts COLD (with your spray), does it have the normal slightly higher IDLE as it normally would (when cold)?

[rodbolt17]

at key on the ECU is looking at coolent temp,baro pressure and TPS it also cycles the HP pump for 3-5 seconds.
at cranking it defaults the injector on time and ign timing so it starts at about 1100 RPM.
all you did with the start fluid is make it rich.
my guess is your injector guy is gonna say you need an ECU when his fix wont work.
if they were that clogged you would be describing other running issues.

[AnotherBoat11]

Thanks for the info - injectors to be back Friday
Hope its not the ECU - hard on wallet

[AnotherBoat11]

For the uneducated - what is TPS

[pstephens46]

Throttle position sensor

[AnotherBoat11]

Can I assume a bad TPS would cause a no start when engine is cold?
I thought I saw a way to test it with a regular meter post by rodbolt17 - but have been unable to locate it again - a link would be helpful
as Always - Thanks

[99yam40]

need to look at the service manual and test like it says.

does this motor use computer to look at all of this stuff?
if so get someone to put it on and have a look

[pstephens46]

need to look at the service manual and test like it says.

does this motor use computer to look at all of this stuff?
if so get someone to put it on and have a look

I thought the X Motor used the Winky Blinky. Who named the thing anyhow?

[rodbolt17]

the old 2 stroke chokers did not use any ISC to control air at cold start. the ECU used ign timing and additional injector on time.
a quick test your tech should have recommended would be to turn the key on, rack the throttle quickly then try to start it.

[99yam40]

the old 2 stroke chokers did not use any ISC to control air at cold start. the ECU used ign timing and additional injector on time.
a quick test your tech should have recommended would be to turn the key on, rack the throttle quickly then try to start it.

Rodbolt, if it does start OK when he racks the throttle quickly when turning the key to the on position while pump is running, does he need to look for something that is causing it not to start by just turning the key

[AnotherBoat11]

Thanks guys - still following

Rodbolt is correct - injectors are not the problem - they all tested 87% or better and have been cleaned - due back tomorrow