Fuel starved?

shess

I have a 2003 rinker 270fv.  I helped out a stranded boat by taking 10 adults plus myself about 2 miles to the nearest marina. I was not able to get on plane with all those people (nor did i expect to) so, i proceeded slowly  to the marina.  After dropping them off and getting underway, the engine began cut out after going above 3200 rpm.  No alarms, no overheating.  I limped back to the the dock at 3000rpm and 15mph.  Does this sound like a fuel filter problem that may have been exacerbated by the heavy load.  It looks like there is an inline filter near the gas tank and one closer to the engine.  Any help would be appreciated.

 

Black_Diamond

The in-line one is a fuel filter, the one that looks like an oil filter is a water seperator. Does not sound like a filter problem though.

212rowboat

Pcm controlled spark and air?

If so, I'm willing to bet your boat will be fine by morning..

We call it the 'dumped load crawl'... I've heard all kinds of suggested reasons as to why it happens, but none solid enough to explain it.. the commonality, though, is after killing it long enough for it to completely leak down, its good to go in dang near every case.. go figure?

I personally think its either a load index being drastically changed as registered by the pcm cross referencing the manifold absolute pressure with the air intake temperature, and bouncing it off of throttle position and rpm and altering the adaptive table because of it, and throwing everything else it's learned out the window until there has been time elapsed and a couple key cycles, or, its hella simpler and its a simple vacuum issue and the same adaptive table referencing the rpm to the vacuum signal and drafting a new map in the adaptive tables.....

I bet if you put a scanner on the thing your short term fuel trim and your long term fuel trim don't reconcile.. I bet the stft is double digits positive where the engine was adding fuel, and it simply hasn't reconciled or tossed the wild data collected during your loaded run.. either of the above situations can, in theory, can cause the pcm fuel trims to trip out, but which is more likely, I don't know...

Oh, and don't laugh.. I've got buddies with theories much wilder than mine!!

At any rate, I bet its fine by morning... Hide and watch.. :-)

212rowboat

Oh... Another set of theories I like:

vacuum in gas tank, absolute fact with small outboard, but never saw a built in tank do it...

Anti siphon diaphragm or positive flow valve in regulator or filter/separator being exercised and stuck..

Eh... I don't know what causes it... I quit.. I need another beer.. I bet you're fine after the engine leaks down, though, and tosses the goofy trims the adaptive table stored by figuring them into ltft's, and in affect washing them.

shess

Thanks for the info.. I like the idea of a problem that goes away by just letting it sit for a day .. I'll keep my fingers crossed and keep you posted...

shess

Just one more question, drewactual... Assuming its is the pcm fuel trims tripping out, does it normally reset on its own with some down time or is there a "reset process"?

212rowboat

Short term fuel trims contribute to long term trims.. short term reacts in fractions of seconds, long term changes, as a result of short term take a lot longer.. think of a shot glass being short term, and a 55g drum being long term... The engine is sipping from the shot glass whilst its running, but when it flushed short term it is dumping the contents of the shot glass into the drum.. when it starts up again, it fills the shot glass from the drum.

The obscene stft's have contributed to your ltft, but its impact is minimal... If you want to start fresh on all adaptive tables because you think they've been 'tainted', start over by pulling power and waiting a couple minutes before reconnecting.

shess

i pulled the power for 5 minutes, then started her up and took her for a spin.  When i initially tried to get on plane, it cut out again at 3200 rpm.  i decided to give it one more shot before bringing her back in.... and to my happy surprise, it ran fine.  4200 rpm and 29 mph which is normal. i slowed her down to zero and took her back up to 4200 rpms several times with no problems.  i get her back to the slip and call the the mechanic to tell him not to bother coming down.  He says he was already there earlier and that the boat needs new fuel punp(s).  (does the merc 350 mag mpi even have more than one fuel pump??).  My question is.... Does his diagnosis seem reasonable considering it ran fine after the one inital hiccup?

shess

Thanks for the quick response Al.  When you say "rebuild the cool fuel with new filters and seals", what are you referring to? What seals should be replaced? Thanks...

shess

Just an update.  I replaced the fuel/ water separator and the inline gas filter.  Took it out today and it ran perfect with no hint of the problem.  The boat is coming out for the winter in a few weeks when i can take a look at the regulator, cool fuel line , etc.  I'm hoping Drewactual's diagnosis was correct and it just reset itself.. .. Thanks for the feedback guys..