2000 250 hp ox 66 high pressure pump looses power

[reelfriend]

have a 2000 250 hp ox 66.while running engine dies.traced it to high pressure pump.No power to pump.Put power to pump sometimes still hard to start.When cranking almost sounds like no compression cranks fast.Sometimes i spray a little 2+2 in intake and it restarts.Ive replaced the fuel priner ,lo pressure pumps, filters ,plugs,bypassed the fuel tank ,cleaned the vst screen.Dont know wha to do next.Sometimes cuts out at idle as well,but mainly at speed.

[boscoe99]

have a 2000 250 hp ox 66.while running engine dies.traced it to high pressure pump.No power to pump.Put power to pump sometimes still hard to start.When cranking almost sounds like no compression cranks fast.Sometimes i spray a little 2+2 in intake and it restarts.Ive replaced the fuel priner ,lo pressure pumps, filters ,plugs,bypassed the fuel tank ,cleaned the vst screen.Dont know wha to do next.Sometimes cuts out at idle as well,but mainly at speed.

When the key is on the pump should have 12 volts to it. The same voltage that is applied to the injectors and the O2 sensor.

Are you saying that when you connect the positive lead of your voltmeter to the terminal at the pump that is connected to the red wire with a yellow tracer, and the negative lead of your voltmeter to the block, that you are not seeing voltage to the pump? With the key on of course.

[reelfriend]

ox 66 hi pressure pump

correct there is no 12 volts at the pump when the engine dies.However if I run 12 v0lts to the pump It still doesnt want to start.It has 36 psi of fuel pressure when running.

[boscoe99]

No voltage to the pump indicates a broken wire, bad connection, defective relay, etc..

The voltage source also applies voltage to the fuel injectors. If you are manually pressurizing the fuel system when the engine is not providing voltage to the pump and injectors, guess what? The motor won't run. Even though there is fuel pressure the injectors won't open to spray the gasoline into the intake system.

[reelfriend]

ox66

That makes sense but what is controling the power.Is it the computer, a relay?Is there a sensor?Also there is a yellow wire at the bottom of the ecm if dis connected puts the engine in limp home mode.But still wont start.

[boscoe99]

The injectors and the fuel pump get their voltage from what is called the main relay. The relay control circuit (opens and closes the relay contacts) gets its voltage from the CDI.

First thing that I would check is to see if the relay is closing when the key is turned to the on position.

If the relay is closing does the relay have voltage to it from the battery?

If the relay is not closing then I would check the wire from the CDI to the relay control circuit.

[reelfriend]

ox 66

I will try that but I beleive it does as I used one of the large red wires on the left side of the block to jump the fuel pump.I will check it.Thanks so much.

[reelfriend]

solution for fuel pump loss of pressure

This was the reason for the engine cutting out.It was the fuelpump resistor that was causing it to die.Runs great now

[boscoe99]

Thanks for the feed back. Glad to hear you solved your problem.

The resistor is in the ground circuit to the pump. No groundee, no runee.