DT150SS Intermittent loss of power/cyl's

[Offshorebouy]

Greetings to all...

Re: DT150SS .... This engine has been a most faithful servant since
1987 with low annual hours currently totalling 460 since new on the
only hull it's ever been on for it's whole life.

It will turn 5900- 6000 RPM WOT which I test briefly every 10 hours
or so just to verify spec. operation, Never to abuse or run hard.
Swinging a 14.25X21P 3 bladed cleaver on a light-weight 24'
Excalibur Sport Vintage Offshore hull with an 18" bracket.

Last 3 seasons have seen intermittent very low power incidents that
seem to occur randomly, may come and go over 2 or 3 run cycles,
then the power stays low. It will barely plane the boat and it feels
very laboured and unresponsive... complete opposite of how it felt
mere minutes ago.

Twice, we've found resistance values off on Throttle Position Sensor
which seems to have solved problem for balance of that particular season.

Different this time though, as cyl. 1 and 6 are not getting any spark...
at least plugs are black and very wet compared to other 4 cyls with
more normal "coffee and cream" appearance, so concluding no spark...
Seems very odd as it had been working great for first 3 hours this season
and this problem came up after a great run to one of our fav
anchorages, sunset picnic and then blaaaaahhhhh....
no power on the way home.

Previous occurrences with the TPS have still shown relatively even
plug colour across all 12 as I recall.

Have assembly manual, but it's beyond my level and hoping to see
if it's a common or typical issue that others have faced.

I googled it and came to a post(see below) on these forums that
sounds similar(and I can appreciate that there could be multiple
causes/reasons), so that's how I found you....

Would very much appreciate any input.

------------------------------------------------------------------

Copy, Posted by "twoslo4five0".....

Hello all. New to the site and hoping to get some much needed help ive been looking for before calling the repair man.

I have a older suzuki 200 v6 12 plug motor. Ive had intermendant problems with the motor. It sat for about a year (the boat did) and i just got it going again. I took the boat out once at the begining of the year and when i went to get on plane or applied any throttle the motor would die. We got it back home checked the gas (it was good) pulled the carbs (3 carbs all clean but cleaned them anyway) and re assemembled. Took it back out and ran great, i was tickled pink.

Well i burned through that tank of gas that day (i hadnt put ANY fuel in since it had sat for a year) and i went to go out and enjoy my day again. Filled the tank before going and sure enough motor didnt want to take any throttle. I slowly got it up on plane after about 20 starts and it ran fine. Got where i was going and fished, went to leave some issue.

All i can think was mabye there was trash in the tank and now ive stired it all up buy putting new fuel in? Some help would be greatly appreciated guys. Oh here is the motor.

------------------------ end of copy ----------------------------------

[boats.net]

Use a timing light to see if any cylinder lose fire at time engine loses power then test ignition components on that cylinder.

[Offshorebouy]

Swapped out coils....

Did not have timing light so swapped out coils from down cyls. (#'s 1&6) with cyl's that are firing and those coils work in the good cyl's... so they are good coils.

.... so what's next?

Seems as though it's up-stream of the individual cyl. components????

[seaox230c]

Do a search for " missing at speed " by seaox230c my DT225 has a similar problem...at speeds above 3200 one whole bank appears to miss and sputter but is perfect below 3000. When I find my problem..it might be yours.

[Offshorebouy]

Do a search for " missing at speed " by seaox230c my DT225 has a similar problem...at speeds above 3200 one whole bank appears to miss and sputter but is perfect below 3000. When I find my problem..it might be yours.

Here is a clickable Cross-referencing link to the above noted.

Missing at speed - Suzuki Outboard Forum

It should take you straight to it.

I will attempt to put a similar link on your post
so if someone finds an answer it will have a better
chance of visibility between the two topics.

This is one drawback of some forums, in-so-far-as they
do not have enough or well enough individualized categories
and useful info can get buried in endless pages of "General".

[Offshorebouy]

Crankshaft Triggers

In a phone conversation, it has been suggested by a local Merc.
Marine Master Tech., that crankshaft triggers can generate these
types of cylinder loss failures.

Does anyone have any experience or insight regarding that
potential in the early, 2.7 litre V-6's?

[seaox230c]

Tried some new stuff today..no help more confusing..thanks for the crosslink. I never seem to have the same failure twice but the net failure is always the same. Today I had all coils sparking normal with the engine sputtering up and down at one point. I am going to pull the injectors and have them cleaned and tested...couldn't hurt. Crankshaft sensors can go bad but unlikely..and if they go bad the issue shouldn't jump around..two going bad intermittently is almost unheard of unless they sustain physical damage,,,I hate boats!!!

[Offshorebouy]

2.7 litre Suzuki V-6 Outboard Ignition Problems

Additional Web searches turned up this item and it
makes sense that the stator assembly located under
the flywheel could be a potential source of many of
the symptoms reported. (See attachment #2)

In the case of my V-6 which has lost 2 cyl's, #'s 1, 6,
the fact that the drawing shows 3 pulser coils means
that each coil fires 2 cyl's., and that could be a handy
explanation for those cyl's to be off-line, perhaps even
more-so when you look at the firing order. (See attachment #1,
page 43, Suzuki V-6 outboard assembly manual.)

As we all know, V-6's are inherently rough idling/running due to
rotationally uneven firing impulses, so hardwire connections
are subjected to immense vibration which over years
can easily lead to poor/broken connections.

Has anyone been into the Crank Stator Assembly?

.

[seaox230c]

You can see the pulser coils..they are 3 little square boxes evenly spaced around the vertical part of the flywheel...under the part with the teeth. Under the electrical and Ignition section of your manual it tells you how to check the pulser coils. I don't know which ones feed which plugs. The book says you need to remove the flywheel and use a special jig to replace...it seems with a rt angle screwdriver and some feeler gauges it could be done with the flywheel on but am not sure without trying it. Are your plugs 1 and 6 dead all the time or just above a certain speed/rpm. It would seem unlikely that the coil goes intermittently bad at a certain speed all the time while testing good at lower speeds..could be but thats the issue with electronics...tough to pin down.

[Offshorebouy]

Ignition Issues

Cyl's # 1, 6 are completely dead at this time.

Swapping those coils into other cyl's they work great,
so thinking it's up-stream.

I'm going back in for another look to see if I can find any
obvious wires off in there.

[seaox230c]

Before you remove the flywheel I would do a resistance check on the 3 pulser coils. My book says 160-240 ohms and it should read 2v output during cranking . I am pretty sure an induced coil output is ac voltage. If that checks good then it might be the cdi or the ignition control unit..both expensive just to throw in for kicks

[seaox230c]

Any luck on your troubles...still working my issues