99 df70 vst

[gvillewill]

My boat sat for a while, so I purged all of the fuel and pulled both fuel pumps and cleaned them before attempting to crank it up. When I did it would not crank but would fire once in a while. I removed the bolt at the top of the fuel rail and there was no pressure on the system, so I hooked up a pressure gauge just before the fuel rail and turned the key on. It went right up to 40psi for about three seconds and then bled off. Turn key off and then back on and same thing happens, right up to 40psi and then bleeds off. Disconnected the fuel line and turned the key on, it pumps gas for three seconds and then stops. I've never had a fuel pump do that before.
I don't want to spend 600+ for a new VST unit and then find out that it was something else. I fist thought that maybe the pressure regulator was bleeding off the pressure, but it seems like the pump should turn back on to bring it back up?

Anybody have any ideas?

 

[99yam40]

do not know much about Dt motors, but guessing that the high pressure pump needs to see the motor to be running for the pump to stay running.
what is this purge that you talk about?
all old fuel needs to be removed from the tank and all lines, pumps, filters, and VST need to be drained and cleaned to get the bad stuff out

 

[gvillewill]

Purging was the cleaning.
It's supposed to stay pressurized once the pump pressurizes the system. I have never seen a pump act like this one seems to be acting. Usually, they either work, or not.
I can see the pressure regulator leaking and let the system depressurize, but the pump should re-pressurize it if it does. But it's not. It's confusing to me. Just looking to see if someone else has had any similar occurance.

 

[gvillewill]

I think that I may be figuring this out. I was reading another post and a guy said that if the ecm does not get a crank signal in three seconds then it shuts the fuel pump down, so that makes sense.
Now its pointing to the pressure regulator bleeding off pressure.

 

[99yam40]

or injector leaking