Answer me this, if you will....

[zeehag]

ok i know you all are smartasses and weisenheimers and other kinds of similar ilk. i have a question regarding fuel flow which so far has not been answerable by use of logic nor common sense nor study of fuel flow dynamics, unless there is another pump working in htis.
whn i departed barra de navidad i presumed my lift pump was working properly , as the mechanic i used to bleed system and fix any issues the ka lunk was showing before i left had said no the pump was not gonnabe rebuilt before i left. ok. symptoms be damned. (no, not the same mechanic who rebuilt my engine.)
ok so i had the electric pump in line, with a switch , turned off, a si didnt need it for stating the engine and running. ok
we slid out of barra lagoon easily enough, despite a hard soft grounding of which w e willnot speak h aha ha ha
and began hearing intermittent surging rpms within 2 miles of out the mouth of harbor. hell no we donot turn back we go forward. and so we did. only 120 miles yet to go, what can go wrong.
south of cabo corrientes, within what should have been one day of punta de mita, the surging becomes more frequent, so i shut ka lunk down to change filter and check oil. that done, we continued on--engine started very easily, and no issues. no surging for half an hour. ok continuing onward-- it took us, for entirely different , long story , reasons 2 days to go one days distance. ok. so we got to la cruz to fuel dock. ok. nother long story. was not an uneventful first wasnt gonnabe a half...(was spozed to be an all in one no stops misadventure). i was most surprised by the weather having laid down seemingly for us, as predicted was not what was encountered thank goodness.....
found cpt to help, left next afternoon, after paying the most pricey marina in miles rent to the following evening-- we ran like scalded dogs.
this guy asked for 150 usd to help get the boat to mazatlan(180 miles). ok is good i told him 200 if i liked his work. ha ha ha ha did he work!!! he even cleaned and cooked the fishie!!! AND made the surging stop.
ok so , now-- was surging, stopped surging, no more electric pump inline-was causing air?? added a airleak for sure making fuel filter for outboard in line systems..ok... and we kept on. had to stop engine and restart for this..now we doing under main that is very small for boat-- no i didnt do that.... and engine restart was immediate. as usual. ok so no w main and engine, 4 kts, average.
ok so we make mazatlan without further surging, and into slip.
didnt know we were stuck in forward, didnt know i didnt have any functional fuel pump--i gave him 200 usd, as we actually made it into the slip not bad.
ok so i had to play musical marina slips for a minuet-- engine started immediately, in forward , went to a different slip. secured boat. all is well.
until time to go back, when immediate start yielded propwash in neutral and no restart after tranny was repaired. reinstall of tranny, still not thinking about fuel pump or system--tried to start--nothing dry cranking.. ok. starter sounds like starting to flatspot..uhoh...
\ new electric fuel pump and my lift is still missing parts i thought were reinstalled in barra--ok..... not done, no lift pump. hhmmmmmm. now all is flowing properly and starting and maintaining prime. but......
i repeat--how the hell did we get to mazatlan without a fuel pump. lift pump was dismantled before we left. electric pump was discontinued midway second half....
ok bring it on........
(fuel tank is well below engine , so gravity is not in play here. at least not in a positive manner.)

[Dulcesuenos]

High pressure injection pump is actually pulling fuel?

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[zeehag]

Originally Posted by Dulcesuenos

High pressure injection pump is actually pulling fuel?

Sent from my PLT1077G using Cruisers Sailing Forum mobile app

i didnt realize they also did that... but the engine started immediately each time until the other day when it refused.
so it is still puzzlement, as everything was same - same until yesterday when it was repaired so i can use it reliably....

[a64pilot]

Originally Posted by Dulcesuenos

High pressure injection pump is actually pulling fuel?

Sent from my PLT1077G using Cruisers Sailing Forum mobile app

Exactly, but is NOT good for them to do that, that is why the other pump is called a boost pump, it's job is to ensure fuel with no air bubbles get to the HP pump, cause cavitation can and will damage the HP pump.

Zee with the luck that you have had in the past with pumps, I'd do an electric and carry a spare, electric pumps of course can't dilute oil.



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[SaltyMonkey]

Originally Posted by a64pilot

Zee with the luck that you have had in the past with pumps, I'd do an electric and carry a spare, electric pumps of course can't dilute oil.

from Monkey!

[Kita]

Yeah,once the thing is primed & no leaks the hp injection pump will pull some, but not alot & as was stated not good to starve it, can damage it & create the surge you had

[w1651]

Gotta go with Dulcesuenos. It probably pulled just enough to keep you going. Either that or divine intervention. But beware divine intervention. It means your Shiiiiite is about to get tossed.

[zeehag]

ok cooool so it isnt guardian angels, altho i am SURE i have a fleet of those, at this point, and not voodoo, altho i welcome that type, nor moon phase or other magical influence.
and would splainme why the prime suddenly quit. and no dirt in filters i changed nor water in bowls of filter....and the need to bleed entire engine, as no fuel was foun din engine.
...
ok so now i have good electric pump and we will be rebuilding the lift pump and keeping eye on injector pump as i donot wish a repeat runaway -- that was once being enoughville

[boatnerd]

Could it be gravity? Our day tank is high up and can gravity feed if jerk pump goes out. .
btw thanks for your help in barra w/ our 4-107 [family on R30].

[zeehag]

boatnerd--i have no day tank-- in formosas the fuel is in tank along keel. below everything..

[reed1v]

My 2 cents: vacuum flow. You had enough vacuum in the line to keep drawing the fuel into the injectors. Does not need gravity feed once you got the vacuum going. The pistons will act as suction pumps to keep the vacuum going.

[model 10]

That pump does not have pistons, it has 2 plungers. No vacuum is possible. You need incoming fuel pressure to push the 2 plungers back for another stroke.

[Elie]

I my opinion, it all may depend on the fuel tank position and the level of fuel into it. As long as the fuel can flow by gravity, fuel feed pump is not a necessity. And in fact the injection pump need very little pressure to get a prime and pressurise fuel to the injectors. And if there is some wave action, that may compound the problem. I have installed a low pressure electric fuel feed pump that can be put in derivation using simple valves. Nice to have in case of problem with the mechanical feed pump, but mainly to simplify the fuel filter replacement.

[reed1v]

Originally Posted by Guy

That pump does not have pistons, it has 2 plungers. No vacuum is possible. You need incoming fuel pressure to push the 2 plungers back for another stroke.

Was referring to the engine's pistons. Basically sucking in the fuel, and with a closed fuel line(it is closed, right?), would be able to self feed. Had an old Singer roadster(it was old when it was new) that ran on that principle, or did not run as the case may be. Hand crank the engine to get the fuel moving.

[zeehag]

ok so how does one go about splaining why the machine restarted so easily--- it has excellent ability to maintain prime... but is that enough to re start this ??