Idles fine, drop into gear - she stalls.

[ShoreFlyer]

My boat is fixed !!

Timing was off by about 10 degrees. It has to be set using a laptop and timing light.

[psubill78]

Our timing was suspect too, off by 3 degrees. Between that and an engine harnass that was very loose, i think our stall is gone!

[psubill78]

I'm bumping my old thread, as now that the weather has cooled off, my issue is back again.

I've got it at the mechanics (a reputable one) and they are baffled. They've spent the last 3 days with her

What they've tested/replaced in the last 3 days :
* Swapped all sensors on the stbd engine (they are focusing on this side first - even though both are doing it)
* Swapped IAC
* Fuel pressure test on TBI - 30-35 psi
* Timing check - all good
* Compression check - all good
* Checked cap/rotor/stator
* Replaced all plugs
* New fuel filter

They are actually working now w/ Mercruiser. However, they even sound baffled.

I'm reaching out to see if ANYONE has any suggestions on the issue. High level issue explained (if you don't want to read the full thread)
* When engines are cold (and environment temp cold) stalls when going from neutral to gear, or even if you let idle long enough, may struggle and stall. Many times I can 'feel' the stall coming by watching tach, and giving a little extra juice on the throttle can generally 'save' it
* Even if engine temp gets to running - it still will stall, albeit less
* After going on a run, and getting the engines on load (even for 10 minutes), and getting engine room warm - the issue goes away.


I am at my wits end, and can't continue to throw $$$$ at this problem, however, when it stalls, i'm shifting a bravo 3 without running - which isn't good either.

HELPPPPPPPP!!!!

[douglee25]

If it happens to both engines, I would look to something that is common to both of them - ie fuel or power, etc.

Check your:

1. fuel line
2. fuel pickup
3. anti-siphon valve
4. confirm the correct spec on fuel pressure
5. confirm battery connections, does it happens with the battery switch in both positions?
6. how about your lanyard? - check continuity with a meter - maybe an intermittent short?
7. check all hardness connections on the motors - do the jiggle test with the engines cold

Doug

[psubill78]

Thanks for the quick ideas.

While it does happen on both engines, it's not at the same time - and very random. IE - one time going out stbd will be the problem, and port never does it. On my boat, there is nothing common between the 2. They are on separate fuel tanks, separate batteries, etc. Generally stbd is the more problematic one.

If it were fuel related, I would suspect my pressure at the TBI would be off, no? Can't I rule out fuel pickup, anti-siphon, etc?

Battery - I haven't wigggled those connections, but have wiggled everything on the engine itself. Battery switches on my boat are on/off.

No lanyard.

Keep the thoughts coming !

[douglee25]

Another question - how can you swap parts from one engine to the other and confirm they are good/bad if both engines exhibit the same symptoms?

Your symptoms sound like a classic bad IAC valve - but you said you ruled that out?

If there are any vacuum ports that are plugged, you could try unplugging them which should raise the idle - similar to what an IAC valve does. It's basically a controlled vacuum leak to regulate idle speed. Then try shifting in gear.

Doug

[psubill78]

The parts they are using are new. I also put in a new IAC in begining of this year. And they put a new IAC in to test today.

And yes, classic IAC, however 2 new IACs have been test. No IAC muffler on the TBI.

I'll recommend the vacuum ports - not sure what those are.

[douglee25]

Well if you're sure the IAC's are good, the vacuum port test is basically pointless. It just mimicks what the IAC is supposed to do.

Doug

[psubill78]

More updates:

* Today - confirmed the following parts were not causing issues:

* Ignition Coil Pickup
* Ignition Coil
* Ignition Sensor

[CliffA]

here is an 'off the wall' idea....could there be a bearing in the drive train that is going bad and causing additional load on the engine when shifting into gear and when everything is cold?.....then after the engine and drive train components and gear oil are warmed up after a while the suspect bearing would loosen up some and not place additional load on the engine when shifting from neutral to forward or reverse gear....could it be possible that this could also be a symptom of a faulty engine alignment with the outdrive due to the same reasons mentioned before by putting too much load on the engine when cold?......

if the outdrive was recently rebuilt or repaired it may be possible that the backlash in the gears may not have been set properly which can produce additional drag on the drive line.....after the components and drive oil are warmed up this drag would be reduced.....

this additional drag on the drive train when cold from either of the reasons above may be enough to stall the engine when everything is cold and when shifting into gear from neutral....you mentioned that you can usually keep the engine from stalling if you apply a little more throttle...that makes sense because by applying additional throttle you are increasing the RPM's and power of the engine to overcome the additional drag on the engine....

you also mentioned the problem is worse when the ambient temp is colder....this is another clue that additional drag on the drive train may be the problem.....when the ambient temp is cooler the viscosity of the engine oil and the gear oil in the outdrive increases which increases the drag on the drive train...

you may want to be sure there is nothing wrapped around the prop drive shaft such as fishing line.....this could also cause additional drag on the drive train....

i did not read the entire thread so if this has been discussed before i apologize...

cliff