99 MerCruiser 454 L29 in Carver 406 - Failed to stay running then OK

[bud37]

Source of the post Understood and the anti siphon is interesting thought as it sounded like she was starving for gas as she went down to 0 rpm.

So I was going to ask....but you seem to have answered the question as to how the engine stopped, abruptly or slowed down sputtering.

Before your guy gets there, clean the spark arrester, throttle body throat and throttle plate.....just a simple wipe will do......inspect the throat for evidence of the throttle plate sticking ( gouges etc).

If your guy has the program, see how many counts the IAC is at when the engine is at idle when it it fully warmed up. That 12.4 volts seems a touch low, read the battery directly with a dvm.

[kgarguilo]

Viper » July 6th, 2023, 3:48 pm

So if there are no maintenance records from the previous owner, then you must perform the regular maint stuff so you have a benchmarked time for when they were last done; all fluids, tune-ups, filters, impellers, etc.

Yes, I have already performed Oil Change w/ Filters, All New Impellers, Cleaned Carb Intakes, Belts, some hoses that looked aged, Lubed Throttle and Trans cables, etc. Any boat I buy, I assume all Maintenance needs to be done as a matter of practice. Engine Hours are only 856 I have put roughly 50 Hours on then since buying in December of 22. Whew it has been a bit of work already.

Voltages need to be taken at the engine, not at helm accessories or gauges.

Understood, I will need to get a second pair of hands for that and will try over the weekeend

The fuel filter cover assembly on your engines is designed to help reduce the amount of radiant heat directly on the filter in hopes of minimizing vapour lock. Again, I don't think this is the issue here but worth noting for others with the same system for future reference.

Understood, not very expensive I will add to my list of projects,
UPDATE: Also, today I tried to replicate the issue and could not get it to fail again while at the dock under cover of a roof. I will also try to replicate this weekend while in a cove for some hours.

I started Port first then Starboard - Let them come up to Temp - No Issue
Then started Starboard first then Port - Still at Temp - No Issue
Started both at once - No Issue

UPDATE: Scheduled a tech to siphon the data from the MEFI-3 Starboard Engine, they will be at my boat next week.

Thanks for the help!

[kgarguilo]

bud37 » July 6th, 2023, 3:58 pm

So I was going to ask....but you seem to have answered the question as to how the engine stopped, abruptly or slowed down sputtering.

The engined stopped by gradually going down on RPM until it was off. Took about 2-4 seconds

Before your guy gets there, clean the spark arrester, throttle body throat and throttle plate.....just a simple wipe will do......inspect the throat for evidence of the throttle plate sticking ( gouges etc).

If the spark arrestor is the same as the flame arrestor, as part of my initial maintenance, I cleaned them thoroughly about 20-plus hours ago and still look clean.

If your guy has the program, see how many counts the IAC is at when the engine is at idle when it it fully warmed up. That 12.4 volts seems a touch low, read the battery directly with a dvm.

Understood and will do. Also, all batteries are new about 35 hours ago Group 31 SRM-31 Dual Purpose Interstate.

[g36]

Might take a look at the diacom software. If your having to pay a tech to hook up the engine a few hundred more will buy the software and you'll already have it for next time.

[bud37]

Source of the post If the spark arrestor is the same as the flame arrestor, as part of my initial maintenance, I cleaned them thoroughly about 20-plus hours ago and still look clean.

Yes......no idea why I wrote spark.....good catch....

Also I will second the Rinda Diacom......

[kgarguilo]

Update: We went out today- Bad day
Bullet points from my audio recording

• Both Engines were drawing from aft tank
• We left port at 10:30 AM
• Destination 1 arrived around 10:50 AM
• Anchored for roughly one hour.
• Departed for Destination 2 at Noon
• Anchored for roughly 3 hours.
• Started Engines I was on Anchor duty on the Bow.
• Raised anchor, lost forward momentum Both engines died 0 RPM.
• Went top helm tried to start – No joy.
• Went to battery switch –
o switched to Position 1 from position 2.
o Tried to start no joy.
• Went to battery switch –
o switched to Position 2 from position ALL.
o Tried to start no joy.
• Dropped anchor 50 feet – Feels like we caught bottom.
• Tried loosening the Aft gas cap
• Tried both Port & Starboard engine again - No Joy
• I left the engine room hatch open - Temp is 72 degrees F in Salon
• Tried switching gas tanks port to port and starboard to starboard
• Tried both Port & Starboard engine again - No Joy
• Switched gas tanks back port to aft and starboard to aft
• Called Tow Boats US – 15-20 minutes on phone.
• Tried Starboard engine again and got it started – ran at 3k rpm.
o After engine settled down lowered to 2k RPM
• Tried to start Port – tougher to start but got going and same 3k RPM.
o After engine settled down lowered to 2k RPM
• Closed Salon Engine Room hatch to get under way
• Next lowered both RPM to 600 and put into gear forward – All running.
o Raised anchor and kept forward momentum.
o Once anchor was up raised to 2k RPM then in a ¼ mile up to 3k RPM all the way back to marina.
o At No Wake markers slowed to 600 RPM and tried reverse prior to going all the way into the Marina.
o All good so I docked the boat with no further issues.
o After turning the boat off tried to start three more times and all successful

NOTE: Voltage again was at 12.4 at Helm Garmin on the way back was up to 13.8
I could not get voltage from Engine room as there we too many boats around us to worry about hitting.
Next stop Engine diagnostics sometime this week.

[km1125]

Source of the post
• Tried Starboard engine again and got it started – ran at 3k rpm.
o After engine settled down lowered to 2k RPM
• Tried to start Port – tougher to start but got going and same 3k RPM.
o After engine settled down lowered to 2k RPM

Just need a bit of clarification on this part. When they started did YOU put the throttle up till they were going 3k RPM, or did the engines do this by themselves?

Prior to this event that seemed to affect BOTH engines, were the previous problems just on the starboard engine or did you have problems with both before?

[kgarguilo]

Km1125

I throttled them up to 3000 rpm as that seemed to keep them running. My gut was telling me to run some fuel through them and or charge the batteries with the alternator. No sure if that was good or bad but, it is what i did.

Correct, first event was only Starboard. This second event both engines were affected.

[Viper]

I assume you have fresh fuel? Have you checked the filters to see if they have any water or a lot of sediment? Have you looked to see whether you have spark at a plug when the engines won't start?

[Midnightsun]

My gut is telling me your batteries are done and engine electrical is insufficient to run them correctly. Your voltage at 12.4 if correct and taken while engines are running, is way too low, should be around 14 or better with healthy batteries and good alternators.

You pulled anchor and lost engines? The juice required to pull anchor is rather large so I assume it took everything away from the engine requirements and further drained the battery/s resulting in a no start after anchor was up.