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

[kgarguilo]

UPDATE: The charger was not the issue but, at least it is now new, and the voltage stayed up for the whole event.

Outside temp was 95 degrees Fahrenheit.

After anchoring in cove for 6 hours, both engines would not start but, the Victron Charger voltage for all banks remained at 13.6v.
The temperture in engine room was 110 degrees
Both engines are drawing from the Aft fuel tank, as a test, I opened the aft gas cap to let the tank breathe, neither engine would start still.
NEXT Hooked up computer to starboard recorded but no luck starting. 3 recording on this engine.
I placed a fan to lower temp in engine compartment tried starting port again with computer attached temp now 105. Tried starting starboard again got it going let run at 3000 rpm's checked temp in engine room and it was at 98 in engine room. Slowly lowered rpm's on starboard to 2000. It stayed running steady.
Checked engine room temperature 98 degrees still. Got port started recorded via computer left at 3000 for period of time then 2000 then closed engine room door and proceeded to leave engines running normal once underway. No issues coming back to the dock about 4.5 miles away and solid as a rock.
NEXT After shutting down at the dock, waited 5 minutes and tried to start both engines again, started right away.

No Error codes still

Computer recordings are here if anyone is interested.
https://1drv.ms/f/s!AsUXzq27eR2fgr4nS_5 ... w?e=R25TAB

Thank you all for the continued help and support.[/quote]

[tomschauer]

When you say the engines would not start, I assume they would crank freely. but not fire up correct?
You say you showed 13.6 volts, do you have someone to look at the voltage while cranking? If it drops under 12, they will not start. As you say they seem to run fine after they start, it really leads to believe you have a battery issue. Bad batteries can hold voltage but drop quickly under any load.
I would consider getting at least one new battery, if your system allows you to isolate it to just engine starting and see what happens.
Always keep in mind, when batteries are in parallel, your system is only marginally better than your worst battery, and the bad battery will quickly kill the good one(s), so when replacing batteries, always replace all batteries in a bank.

[kgarguilo]

The engines fire but as seen on the videos the rpm graduallygoes down to 0. I am viewing the actual voltage (real time display) on each battery while cranking / starting on the Garmin through the nema 2000 gateway of the new victron skylla ip65 charger 70 amp. The engines start but do not stay running. At no time did the voltage drop below 13.6. It is like they are starving for fuel. The generator was running all day charging all batteries as well. The batteries all test good very good in fact with a load tester.

[bud37]

You have done some great background work for your issue......many folk would not go this far, kudos......now it is starting to look like perhaps some sort of vapor lock/heat soak.....considering both engines exhibit the same problem at the same time. The fuel source for each engine is completely separate correct ???? The temps don't really seem that high though, how are you getting the readings?

You could try to insulate your fuel lines with some fire retardant compliant wrap......years ago some factory lines came insulated on some boat engines. As an aside....do you have one of those fuel lift pumps installed somewhere ? I am led to believe there was something along those lines installed afterwards to combat this type of issue. Just a guess on my part though.

I will check out your recording , may take a while....

Things like this can have multiple different causes so unless someone has encountered exactly what you are explaining it will be a bit of an educated guessing game. Cross some simple cheap fixes off the list.....lines etc will always need upgrading so will be a benefit down the road.....imo.

[bud37]

I have one other question....before this started did you change your fuel source ( where you buy fuel ), fuel grade etc ???

[km1125]

So if I'm getting this right, this problem ONLY happens after it's been sitting for a LONG time in extended temperatures. If you went right to the anchorage and shutdown, but then tried restarting the motors within the first 15 min or so you would NOT have the problem, but if the motors are sitting for HOURS in extended heat that is when they don't restart. Is that very consistent or are there times when it would not restart after just sitting for a short period of time?

Source of the post

"Wonder if the "cool fuel" module wasn't doing its job keeping the fuel cool?? Does that engine have one of those modules?"

While it does have a fuel cooler module, it relies on water going through the engine from seawater which appears to do nothing until the engine is running, and has water passing through it, I think. btw the sea water strainers were cleaned less that 30 days ago and they were clean already. Thanks for helping.

That's not really true. The colder seawater that's just sitting in the system is a buffer against the high temps in the bilge.

The original posts seemed to indicate there was a low voltage issue and that the start-then-stall was coincident with the winch usage. After more posts and clarification (and the charger change), I'm not inclined to think this is a battery issue, since the engines DO actually start fine, but THEN stall. You wrote in one post early that they just wouldn't start and that gets confusing, but later clarified that it was the same start-then-stall symptom.

Have you checked/changed the anti-siphon valves?? They were discussed early in the thread but I don't see resolution (unless I just missed it). THEY control the pressure in the section of line from the tank to the pump and actually cause a VACUUM to form in that section. That makes that section of the line (including any filters) VERY SUSCEPTIBLE to vapor lock in higher temperatures. Everything AFTER the fuel pump (even a "lift" or low pressure pump) is at a higher pressure which makes it harder for vapor lock in those sections.

They are cheap and relatively easy to replace. That would be my next recommended move.

[kgarguilo]

Source of the post

Postby bud37 » July 28th, 2023, 10:34 am

You have done some great background work for your issue......many folk would not go this far, kudos......now it is starting to look like perhaps some sort of vapor lock/heat soak.....considering both engines exhibit the same problem at the same time. The fuel source for each engine is completely separate correct ???? The temps don't really seem that high though, how are you getting the readings?

Thank you, I am interested in this and like getting deeper. Yes, confirmed happening to both engines at the same time. Yes, there are two fuel hoses coming from the aft tank and both go to their own diverter valve and then feed each engine individually. Yes, both are set for aft tanks. Selector switch can be OFF/Port/Aft for port engine and OFF/Starboard / Aft for Starboard engine. I used a portable thermometer and placed it on top plywood cover / step cover for the battery bank between the engines. https://www.lacrossetechnology.com/products/308-1911v2

You could try to insulate your fuel lines with some fire retardant compliant wrap......years ago some factory lines came insulated on some boat engines. As an aside....do you have one of those fuel lift pumps installed somewhere ? I am led to believe there was something along those lines installed afterwards to combat this type of issue. Just a guess on my part though.

I do not know, If I have a lift pump; I will have to look around and follow the fuel lines, any guesses where it would be? Engine room and on the way from the tank.

I will check out your recording , may take a while....

Thank you

Things like this can have multiple different causes so unless someone has encountered exactly what you are explaining it will be a bit of an educated guessing game. Cross some simple cheap fixes off the list.....lines etc will always need upgrading so will be a benefit down the road.....imo.

Understood, I am patient, at least I can still take the boat out. Just sitting around for a few hours is a bad idea right now.

I have one other question....before this started did you change your fuel source ( where you buy fuel ), fuel grade etc ???

Yes, I think the timing is right, I changed marinas as the delta is nearly $2.00 per gallon for the same octane and type of fuel. However, many people on my dock are using the same fuel with no issues. I have filled up twice since this started and need fuel again.

[kgarguilo]

"km1125"]Source of the post So if I'm getting this right, this problem ONLY happens after it's been sitting for a LONG time in extended temperatures. If you went right to the anchorage and shutdown, but then tried restarting the motors within the first 15 min or so you would NOT have the problem, but if the motors are sitting for HOURS in extended heat that is when they don't restart. Is that very consistent or are there times when it would not restart after just sitting for a short period of time?

The shortest period I have tried has been 2 hours. However, after the event of not starting I get back to the dock and start it no issue

Source of the post

"Wonder if the "cool fuel" module wasn't doing its job keeping the fuel cool?? Does that engine have one of those modules?"
While it does have a fuel cooler module, it relies on water going through the engine from seawater which appears to do nothing until the engine is running, and has water passing through it, I think. btw the sea water strainers were cleaned less that 30 days ago and they were clean already. Thanks for helping.

That's not really true. The colder seawater that's just sitting in the system is a buffer against the high temps in the bilge.

The original posts seemed to indicate there was a low voltage issue and that the start-then-stall was coincident with the winch usage.[/quote]
CORRECT, this time they stalled before the winch was even used, learned my lesson to wait before raising the anchor.

After more posts and clarification (and the charger change), I'm not inclined to think this is a battery issue, since the engines DO actually start fine, but THEN stall. You wrote in one post early that they just wouldn't start and that gets confusing, but later clarified that it was the same start-then-stall symptom.

CORRECT - Symptoms have remained to same - The engines have always started and slowly faded to 0 RPM OFF. Originally it was only one engine and has now progressed to two engines. The new charger has eliminated to lower voltage issue

Have you checked/changed the anti-siphon valves??

I do not know what that is or where I would look for it. Is that the overflow for each tank?

That would be my next recommended move.

Once I learn what and where they are I can do that.

[kgarguilo]

Source of the post I have one other question....before this started did you change your fuel source ( where you buy fuel ), fuel grade etc ???

Because I started thinking about this one, I had two new fuel filters in my spare parts, so I swapped them both out preventatively and did not see any water in the fuel that I poured out.
I also asked two people n the dock that I know are filling up there as well. No issues with their engines at all.

[bud37]

Next time you go out set the fuel feed for each engine to a different tank, if I understand you saying that both engines are pulling from the same tank.....separate them would be my advice at this point and we will see.