Died on water

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Well, I am always reading these posts, but now I need a little individual help... First, everything seemed fine and has all season. Went out a few miles, let it idle for an hour, shut it off and checked the oil as I do from time to time. Oil looked perfect, though I noticed small dots of water on the upper half of the dipstick, which I hadn't noticed before and find a little odd. I turned it back on, but right before it started I saw that the voltage of the battery was only at 10, lower than normal. It started, but I could tell it was with less power. I only say those two things because though they appear to be coincidental, maybe it will help identify an issue. After it started, I ran WOT back up and did a little more driving, noticing that it was losing power the further that I went. It seemed the rpm's remained the same, around 4600 (which is less than the 4800 at WOT normally), but it wasn't going as fast somehow. Then I decided something must be wrong. I went towards the dock, pulled the throttle back and the engine sputtered and died. Would not start again, I jumped both batteries together to make sure I had enough juice, but still wouldn't start. Opened the hatch, everything seemed normal. Kept trying and took about 20 minutes before it even tried to start, gave it a lot of gas, then it hesitantly started. Ran really rough, but was able to get it back to the dock. Got home started on muffs, but still very rough.

After reading a lot, it seems it may be due to the fuel pump...though I don't know, seems odd. I did get 10 gallons of gas before going out which gave me roughly 3/4 of a tank, ended up with 1/2, but it did seem like it ran out of gas when it stopped, though clearly didn't.

I have a 2008 Volvo Penta 5.0 gl with an SX drive. I would appreciate any thoughts. Thanks everyone!
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
12,944
Water in gas, a cylinder not firing. How does the oil look now?
 
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Water in gas is how it feels...but how that would be possible at this point is beyond me. Have run it at least 6 times this year and haven't had problems, and just put 10 more gallons in it before going out...haven't had a chance to pull the fuel filter off to check and haven't checked the oil yet, it was raining yesterday.
 
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No water in the gas, at least none in the gas filter. Still has water droplets on the oil dipstick, but oil doesn't look milky. I'll drain the oil completely tomorrow and see what it looks like I guess.
 
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I think that the engine is running a little cooler (maybe 5 degrees or so per the temp gauge) than usual also, but that could be in my head...any ideas?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,306
if your voltage drops to 9 volts, your ignition and other electrical things such as relays and fuel pumps will turn off.

you state your voltage was at 10..... that is an indicator that you lost your alternator.

start diagnosing
 
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I'm bringing the batteries in for testing tomorrow. But after the boat died, I linked both batteries together to get maximum voltage. I still had to wait for the boat to start, but once it finally did, it still ran like crap, though I didn't notice the voltage at that point...I did notice it was down to 10 volts earlier, but once started it went to 12.
 
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I think I only have one low pressure pump, I can't find any other fuel lines coming off the carb either.
 

Tassie 1

Chief Petty Officer
Joined
Apr 13, 2018
Messages
581
Pull the plugs
do a compression test
as per # no.6


check fuel tank level too,
just in case
 
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Thanks for all the responses so far! Does anyone know what the compression values should be for this boat? And let's just say there is an issue there, is that going to mean new engine?
 
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Took out the spark plugs, one looks like it blew up...the rest look good...what's next? I know it could've blown a rod in this situation, pulling the valve cover off now...
 

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Make that two plugs that look like that. One on either side of the engine, in the same place...
 
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Took one sides valve cover off...looks fine. Not sure, but maybe 2 bad spark plugs....?
 
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Well, went out and got new plugs...hopefully that'll help and they won't get destroyed too...batteries both checked out too
 
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I asked around and was told maybe the spark plugs were gapped incorrectly... any thoughts on that?
 
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The engine compartment flooded the time prior to this, how would that have affected this?
 

rtpguy

Cadet
Joined
Aug 9, 2019
Messages
7
Any ideas on how the two plugs look like that?

That plug, to me, looks like possible catastrophic damage. The insulator is cracked and missing chunks, and looks like the electrode may be as well. I'd look at getting a cheap borescope to connect to your phone and look at the pistons in those cylinders.

What 'could' have caused it? Those are looking rough enough I don't want to guess - massive timing and detonation problems? Unsure, but I'd be taking a look at your pistons via borescope.

For reference (automotive but it's not like your boat engine is different RE: fuel/air/combustion):
https://www.onallcylinders.com/2012/12/20/reading-101-how-to-read-your-spark-plugs/
 
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