Sx250 dies at around 3.5k RPM

[ttles714]

I have twin SX250 (ox66) 2001... port motor idles fine, throttle up to 3.5 K RPM and dies. I can feel a "clicking " in the shift control. Then re-starts and does this sequence about 4 times ....then runs like it should with no problems. All fuel filters (racor, vst, engine, injector) new. Any ideas or trouble shooting would be appreciated. I am thinking low pressure fuel pumps, but I am not sure if I am looking in the right direction.

[rodbolt17]

monitor the fuel rail pressure at the problem rpm and load.
that clicking is the propshaft rotating backwards while its in gear engine off and the hull still moving fwd.

[ttles714]

next step ? sx250 dies at 3.5k ..Rodbolt ??

Thanks for your attention..by monitoring the fuel fail pressure, I assume you mean connecting a pressure gauge to the schrader valve near the VST. ??? What am I looking for and what is my next step ? Does this test the high pressure pump ? Is there a way to check the LP pumps. (I've tried to find information on this and its a little shaky in my head) .. Why does the symptom vanish after 4 times ??? That's got me even more confused. PS..Rodbolt, I am a commercial laundry tech (the LES stands for Laundry Equipment Service).. if you ever need help with your washer or dryer, I would be more than happy to return the favor.

[rodbolt17]

fuel rail pressure should remain at 35 PSI = or - 3 psi at ALL engine RPMs and load.
at key off it may bleed down to about 25 PSI but should hold for a few minutes to hours.

[ttles714]

rodbolt, thanks , another question

if fuel rail pressure no good, bad HP fuel pump ??? >>>> if pressure OK Then bad LP pump ????? Am I on the right track ?? The intermittent failure of WHATEVER has me puzzled ?

Thanks

[jb123]

much easier to help AFTER you test rather than explain the complete system / symtoms
to test lp pumps, unbolt, pump ball and if any gas comes out of vac port, replace

[ttles714]

just looking to fix

I figured if I had the whole picture I would get it repaired faster. Rather then bits and pieces and loosing time waiting on the forum for further instructions. I read the service manual in reference to testing the low pressure pumps with a mity vac. My M.V. is a little different and I am a little confused as to whether they are testing pressure or vacuum. There are 3 simple pictures, but I am not getting it. Any way thanks for your help. It is appreciated.

[ttles714]

problem solved

thanks for all the help....the problem was a LP fuel pump. unbolting and squeezing the ball showed fuel leaking at the backside of the pump. Thanks jb123, and rodbolt