low pressure pick up fuel pumps

[Grandpaw]

2000 OX 66
2 stroke
250 HP
fuel injected
SX250TXRY

Starting issue , ball soft , pump away ball gets firm , once going I can shut and engine starts instantly , let it sit difficult starting , ( ball soft )

Loosing prime
would soapy water bubble , ?

Not sure if this issue starts at fuel pick up. ? assembly spins , comes out with pressure snaps into a o ring , Plastic tank

Discovered one of my low pressure pumps leaking fuel when loosened , ball pumped

Have a set of used pumps with the fuel primary bowl attached , would be nice to rebuild pumps , nobody offers rebuild kits ( that I can find ) opened one , salt residue

I could take a chance and use one of the pumps too replace the leaking one but not eager too throw used parts ,

Realize best too change all 3 , or would you recommend purchase of one pump too replace the leaking one ,

[99yam40]

VST should stay full while just sitting,
unless a hot motor vaporizes the fuel in the VST.
if that happens maybe it would cause an over rich condition causing the cylinders not to burn properly.
too rich or too lean will keep spark from igniting the mixture.

pump the primer until VST is full.
drain VST and catch what comes out to measure how much.
pump primer again to fill VST full, and then let it sit for a day or hours, and then drain it again to see if same amount comes out.
this will tell you if the VST is somehow losing fuel while sitting while cold.

you could drain it after letting it sit with motor hot also if that changes things

I would replace all 3 lift pumps just so you know they all are new and good.
you can save some of the old in case you need one later on in an emergency.

not sure what you meant with "would soapy water bubble , ?"

every connection between the lift pumps and fuel tank can leak even the o rings on filters and tank allowing air to be sucked in( not out), but I do not see how that would drain the VST.
If the VST has fuel that pump in there should pressure up the rail and injectors when you turn the key to start

[Grandpaw]

GOOD AVISE - will get on it during week , -

[Grandpaw]

Replaced with Yamaha low pressure pumps ,
Drained VST tank , filled and few days later drained , same amount
Still having tuff time starting , , battery charger on battery , crank , eventually starts , will fire instantly - seconds after shutting , few times , by third start WILL NOT ,
Don't want too kill starter , -
ball hard

I did put a mulit meter on battery , engine running , volts , 12,6 ,
engine off battery is also weak 12.5
Have 13,5 volts , from charger going into battery while cranking

could my starting issue be weak stator , not enough juice too fire engine , , and i have been thinking fuel all this time ,

[DennisG01]

Replaced with Yamaha low pressure pumps ,
Drained VST tank , filled and few days later drained , same amount
Still having tuff time starting , , battery charger on battery , crank , eventually starts , will fire instantly - seconds after shutting , few times , by third start WILL NOT ,
Don't want too kill starter , -
ball hard

I did put a mulit meter on battery , engine running , volts , 12,6 ,
engine off battery is also weak 12.5
Have 13,5 volts , from charger going into battery while cranking

could my starting issue be weak stator , not enough juice too fire engine , , and i have been thinking fuel all this time ,

If it's turning over quickly enough, it's fine. But your engine running charging volts is no good. If your reading is correct, you have an issue with the charging system. But check again with the idle around 1,500RPM.

Side note on a battery charger... while it's supplying 13.5 volts, it's not really helping with turning over the engine. Volts are different than amps - you need amps to turn an engine over - which a regular charger won't supply nearly enough of.

12.5V for a resting voltage reading is not great... but not terrible, either.

When you actually run the engine - do you have any problems? If not, then fuel isn't your issue.

[99yam40]

motor needs god compression, good spark at the correct time, and the proper fuel to air ratio for the fuel to burn.
too much fuel or too little could be a problem.
when the motor will not start, is there still good spark ?

did you drain the VST when it will not spark?
have you monitored the fuel rail pressure when it will not start and when it will start to see if there is a difference?

[Grandpaw]

Dark ,, Spark plug Test light , cranked did not attempt too start , All 6 plugs had spark
hooked up water , Fired engine , started ,
I was thinking something with fuel rail ,,when you mentioned it , , Will go on utube and see how too test pressure.
weak high pressure pump ,?
I put sea foam in tank while it was running yesterday too clean injectors ,
thanks for the help

[DennisG01]

From post #5:

When you actually run the engine - do you have any problems? If not, then fuel isn't your issue.


Fuel pressure is easy - get tester (harbor freight is fine) - screw it onto the Schraeder valve - purge it - read the pressure - both at key on and engine running.


Sea Foam is a shot in the dark at actually cleaning the injectors - but your injectors aren't the problem.

[ausnoelm]

Sea foam is a shot in the dark, with a blind fold on and your back turned……..it’s not going to fix anything.

[99yam40]

motor needs god compression, good spark at the correct time, and the proper fuel to air ratio for the fuel to burn.
too much fuel or too little could be a problem.
when the motor will not start, is there still good spark ?

did you drain the VST when it will not spark?
have you monitored the fuel rail pressure when it will not start and when it will start to see if there is a difference?

should have said start not spark