vst pump fuel pressure low!!!

Joined
Jul 10, 2016
Messages
7
my 2008 200 hpdi Vst pump, (some say medium pressure pump some same hp pump) anyways, im having a problem once the motor gets hot, it boggs down for a few second as soon as i break pad, then she cleans out and runs great. so i put a fuel gauge on the vst shradder valve and im only getting 18psi (very slowly 5 seconds) with key on as well as while idling as soon as i turn key off the gauge falls to 0psi. I tore into VST pump to inspect and everything looks good, put it back together and only getting 12psi now. might i add the motor blew recently and i had a complete new powerhead put on, all new fuel lines, filters and tanks scrubbed. so i dont think theres and fuel restrictions due to filters etc. the vst filter was clean when i pulled it.

does anyone have any suggestions as to why im only getting 18psi other that the pump being shot? can it be anything down the line thats possibly causing this? I pulled the line going from lp fuel pumps to vst to possibly rule out a vacuum.

any suggestions would be greatly appreciated before i fork out the cash for a new pump, goodness they are expensive for what they are.
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,842
did you replace the pick up screen on the pump along with the prefilter filter before the VST?

do some research on what controls the recirculation
seems there maybe a check valve to tends to not seat properly on some motors do to corrosion, but I do not remember what motors
 
Joined
Jul 10, 2016
Messages
7
well i did all the research i could. bough a new fuel pump, installed it and checked pressure, its 50 psi. so i started boat and it ran for a few seconds then shut off. now i cant get it to fire up. is their a trick to priming this system? i have never had this issue in the past when i changed the VST filters etc.
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,842
what is the fuel pressure now when it will not start?

Does this motor have lift pumps too?
maybe they are not bringing fuel from the main tank for the other pumps to use
 
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