Throttles back - instanly self recovers

[Peter Werner]

2013 300 HP w/460 Ehrs. Runs perfectly, uses no oil, serviced regularly. Problem: While running at cruising speed, multiple times (4 in past couple weeks), has quickly throttled back (near stall), then instantly self recovers to running rpm. Almost like a "fuel" hesitation. Am on long distance trip in SE, AK and have run through multiple tanks of fuel - and Racor see-through pre-filter is clean as a whistle. When it happens it recovers and does not reoccur for days. Initially thought I had accidentally bumped throttle - but has happened too often, and last two I am certain no contact with throttle handle. Any history or ideas?

[ChrigelKarrer]

You have a digital trottle system and not cables. and that makes it a bit more complicated to trace this problem.
Basicaly there are several problems:
a) problem with the control itself
b) problem with the engine harness from the console to the engine or a involved plug
c) the servo motor who command the accellerator
d) fuel related problems, fuel starving due to fuel pump failure

This kind of non repeatable problems are very hard to trace so i would start with a in depth comuter diagnosis to see if there are some strange values or not on the SMIS gauges shown error codes stored.
If this gives no result then you may check all cables and connections, in particular the connection to the engine control and to the servo motor.
Next step would be opening, control and cleaning/replacing all filters, the VST and replacing the fuel primer bulb.
The last (and most expensive) step would be to swap involved parts with known good ones and one by one till you found the faulty unit.

As the engine just bog down and get back to the original speed/rpm i guess that the problem is not the control itself,
i would start with switching the BCM, then servo motor and control and latest the fuel pump.

Is there any special condition when the engine bogs down or is there a similar time/speed frame when it occurs?
I had a similar problem on a older engine and every time i hit hard a wave one engine switched off.

Chris

[Moonlighter]

Have you actually drained the Racor filter and checked, by pouring the contents into a large glass jar, that there is not water in the fuel? I have seen several cases where the filter was so full of water that the clear bowl looked OK bit was in fact full of water.

That would be the very first thing I would check!

next....

Have you checked engine temp at the time this happens? Has it gone up at all?

And, are you sure that the throttle friction setting isnt set too loose so that the throttle is falling back down when you hit a wave?

If none of the above, it could be a simple electrical connection issue. I would clean all battery connections, check the master battery switch wiring and clean all connections there too.

[artdf175]

Is any of your electronics acting up when this condition happens?
Like depth finder shutting down ?
What you describe starts happening to me
Be running along and engine would city off for a half second and recover
It was the start of the "white wire" problem
This is he source of power to the ignition key that then powers the ECM
Art

[Peter Werner]

Thrtls back...

Art, Moonlighter & Chris: Thanks - great feedback. Always a fraction of a second "dropoff" then self-recovers to same rpm. Will check fuel filter as suggested - but believe problem electrical. Have not noticed other elecs shutting down. Just arrived Sitka, AK last night - will start TSg this morning. Was interested in most likely places to start - will likely contact local S dealer today for input as well. Thanks again - will let you know results - or be asking more questions - later. As we are over 1K miles from home and lots of big water between - don't want to do something stupid. Really appreciate your support - Pete

[Peter Werner]

Thrl back ....

Additional info:

Occurs even in smooth water (non ballistic) conditions.

Have not looked @ engine temp @ incidence - but regularly do while running - nothing out of order then.

Always has happened while at higher running speeds - and well into sustained runs. We have made many long runs between SE, AK ports.

When it occurs - once every few days - it happens once, self recovers - does not occur for days. ???? This last point makes the least sense and challenges the TSg. Likely - solely coincidental.

Thanks again for your time and input - Pete & Susan

[artdf175]

Peter
If it is the electric issue.. then here is where I would suggest you start looking
off the battery switch.. there should be a short red lead that has a connector with high probability of a white wire on the other side.. this is where my wire went bad.. inside this connector.. copper wires corroded completely out..
if you have to cut and reconnect..
my white wire also connected to the dash and then back to the ignition switch.
reason for asking if other electronics were interrupted.. .. since you are not, then the white wire probably connects directly to the ignition switch..
check those wires with a volt meter..
when you turn the ignition switch on.. it powers through this directly to the ECM.. if power is interrupted .. the engine dies..
so 1- check the white wire connection.. put a prob into white wire side and test the connection
of ok go to ignition switch..
there also has been noted the connection inside the engine housing.. one guy had some corrosion on this connector that effected the power to the ECM
let me know what you find..
Art

[Peter Werner]

Thrtls back .... Got it...Feel stupid

Feel adequately and appropriately stupid. It was the fuel filter!! Always happening at higher running speeds should have been the clincher - but other associated behaviors confused.

History: (if UR interested)
When re-powered w/OB, switched pre-filter; from Racor METAL-case to Racor/Parker plastic snap-in SEE THROUGH. With metal case - replaced often due to not being able to VIEW status.

On this extended AK trip: Since June 5, we have logged almost 150 engine hours and gone through 875 gallons of fuel from some odd AK locations.

I carry spare FF but "visual" of running filter "looked" good. Note: VISUAL can FOOL !!!

This FF product has a specified flow rate of 26 GPH - just above my maximum use - that's when new & clean

FF had some hours on it when we started (won't tell you how many - I'm ashamed enough) - so combination of my failures, passage of lots of fuel, and "good" visual got me.

I was lucky - considering some of the straights we have been in.

Thanks all for your support and input. Pete

[Moonlighter]

Good news that you found the cause and got it sorted! It is often the simple maintenance things than catch us all out!

We change filters every 12 months or 100hrs, whichever comes first. These engines do like clean fuel at the right pressure/flow, and good power supply. I would hazard a guess that around 25% of reported problems here on the forum would be related to one or the other of those issues.

So thanks for reporting back so we all can learn from your experience.

[artdf175]

Peter
Keep my comments handy
If it was just a filter problem it would show right back up
I'll stick by a temp electrical break in power to the ECM
It could be on a connector on the power lead from the battery to ignition switch
It could be In the ignition switch
Temporary glitches are a bugger to figure out
IF I am right it will eventually just quit and won't turn over and the trim on your remote will not trim up or down Trim on side of engine will still work different power source
Keep your electric meter handy
Good fishing and good luck post some pictures
Art