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Engine sat for 2 years with gas (prob enthanol). Removed all gas from tank. Replaced pickup tub in tank and all fuel lines, primer bulb and filters in the entire fuel system. Cleaned out vst tank, new filter and gasket, cleaned fuel rail, coolers, injectors, high and low pressure pumps. High pressure pump was checked to make sure pumping correctly by mechanic, no issues. Boat cranks first turn of key and runs perfectly at initial start. Will run for hours. After turn off and let sit for say an hour, still cranks on first turn of key and idles fine and runs fine at below planning speeds, however on the next hole shot runs strong for a minute or so then bogs down, Rpms drop significantly up and down, shift to neautral, pump the primer bulb hard and then runs perfect until cut it off again at all speeds. Done same thing last two weekends. Odd that no issues on the first start of the day, but only bogs down after initially running and being turned off. Maybe low pressure pump? Thoughts?
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Hi.
If the bulb is going soft, then there's a leak somewhere in the fuel system. Check the diaphragm in the low pressure pump and all the fuel line connection points from the tank right up to the fuel rail. If you have those thin wimpy metal clamps on the connectors for the low pressure pump and the onboard fuel filter, I would replace those with zip ties or stronger metal clamps that can be tightened with a screwdriver. For the thicker lines between the tank and the engine, only use the stronger metal clamps (not zip ties).2011 F50TLR, 2010 G3 V167C -
primer bulb will always not stay firm when motor is running because it is on the suction side not on pressure side of lift pump.
something is keeping the VST from staying full with just the pump.
seems you can manually fill it with the primer bulb.
sucking air, restriction,recirculation valve, pressure relief,or pump not coming on when it should.
why after running and shut off is the big questionLast edited by 99yam40; 06-03-2019, 03:05 PM.Comment
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Mechanical low pressure pump so it runs all the time. Possible that something is loose with all the work that was done to fuel system.Originally posted by 99yam40 View PostComment
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fuel cooler is the only thing I can think of off hand. boiling the liquid fuel out of the VST and pushing back thru lift pump, but that should not happen do to the check valves in pump.
what else could keep a mechanical pump from pumping while motor is running?
Air or vapor(no liquid)
is there a way to measure the lift pump pressure before and while the problem happens to see what it is doing?Last edited by 99yam40; 06-03-2019, 03:08 PM.Comment
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All the clamps are the ones you screw with screw driver, but can recheck and make sure everything seems tight and no leaks. The diaphragm in the low pressure pump looked okay, but I want to say now that I think about it when originally took the pump apart there appeared to be a small drop of dark oil on the diaphram that I just wiped off. Does that tell us anything? I am sure the pump is original as screws were very hard to get off. Motor only has about 200 hours.Comment
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I didn't read the OP say 'the bulb is going soft" -Originally posted by rejesterd View Post
but then, what does that even mean, anyway?
how could anything relating to the fuel rail cause the bulb to "go soft"?
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If you couldn't see any obvious tears/holes in the diaphragm, it should be fine. I don't think a small drop of oil could account for your symptoms. Tough one to narrow down, but if the issue goes away when you pump the bulb, to me, that means there's a leak somewhere. Once primed, the system should stay primed if it's truly sealed and the fuel tank is venting properly.Originally posted by Palp0150 View Post2011 F50TLR, 2010 G3 V167CComment
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Hmmm. Wonder where that oil may have come from? I would take the pump apart again and have another look at the various components. Might also look hard at the engine oil for possible fuel contamination.Originally posted by rejesterd View PostComment
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