Motor Issues, Pulled Plugs and Look Unused?
05-27-2019, 03:55 PM
#1
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Motor Issues, Pulled Plugs and Look Unused?
Long story short, after I pulled the boat out of storage, I swapped the jets on my carbs to run a little leaner. I swapped in new plugs as well. Everything went fine, fired the motors on the hose and everything seemed good. Snappy throttle, excellent idle - just as before I swapped jets and plug.
Went out on the boat today, seemed to idle fine out of the marina. Ran it for a bit to ease into it and eventually worked up to 4k rpm and a decent pace. Powered back to the marina seemingly okay. Came in at idle and the port motor turned off. Fired it back up, ran for a few seconds, then died again. Came in on one.
Pulled the plugs:
Starboard
Port
I pulled all the port plugs and they look the same, basically too clean and like theyve never been fired. The first one I pulled seemed wet with water, as it did not smell like fuel. The motor fires up every time, but now idles rough and sounds very sputtery and wants to die, especially when I bump it into gear. I can rev it up, but seems slow and it just sounds off and vibrates. I checked all spark plug wires, everything is properly seated and connected. I can even pull a few spark plug wires off and see no noticeable difference n idle quality or rev. Oil pressure is good. I didn't have to tools with me to do a compression test. Checked the oil, that looked perfectly clean and no milkshake.
After trouble shooting, an observation is the port motor water temp would not get over ~110 at idle and seems to be dumping more water than the starboard motor. I have a silent choice, and when it closes the valve, there is an abundance of churned water on the port side, more so than starboard.
Any ideas as to whats going on?
Went out on the boat today, seemed to idle fine out of the marina. Ran it for a bit to ease into it and eventually worked up to 4k rpm and a decent pace. Powered back to the marina seemingly okay. Came in at idle and the port motor turned off. Fired it back up, ran for a few seconds, then died again. Came in on one.
Pulled the plugs:
Starboard
Port
I pulled all the port plugs and they look the same, basically too clean and like theyve never been fired. The first one I pulled seemed wet with water, as it did not smell like fuel. The motor fires up every time, but now idles rough and sounds very sputtery and wants to die, especially when I bump it into gear. I can rev it up, but seems slow and it just sounds off and vibrates. I checked all spark plug wires, everything is properly seated and connected. I can even pull a few spark plug wires off and see no noticeable difference n idle quality or rev. Oil pressure is good. I didn't have to tools with me to do a compression test. Checked the oil, that looked perfectly clean and no milkshake.
After trouble shooting, an observation is the port motor water temp would not get over ~110 at idle and seems to be dumping more water than the starboard motor. I have a silent choice, and when it closes the valve, there is an abundance of churned water on the port side, more so than starboard.
Any ideas as to whats going on?
05-27-2019, 04:09 PM
#2
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swapped the jets on my carbs to run a little leaner.
Brand new plugs and starboard appears to be running rich, and with seeing water on port, you may have detonated and have some damage. Suggest compression test
05-27-2019, 05:41 PM
#3
In order to do a plug color test you use used plugs and run the engine at the RPM you want for a couple of minutes and pop it into neutral and shut it off right away. don't idle at all. Pull the plugs and check the color.
sounds to me like you may have damaged your engine.
Also understand that you can melt pistons at just about any RPM besides idle.
I melted pistons before at cruise RPM (3500)
There is more to changing your mixture with a carb than changing jets.
The idle screws set mixture even after the throttle is cracked open.
The main jets are mostly for midrange on up but are not the main fuel flow at wide open throttle.
The power valves are for any time the engine is under heavy load. ( getting on plane and wide open throttle)
And there are many other adjustments that can me made.
sounds to me like you may have damaged your engine.
Also understand that you can melt pistons at just about any RPM besides idle.
I melted pistons before at cruise RPM (3500)
There is more to changing your mixture with a carb than changing jets.
The idle screws set mixture even after the throttle is cracked open.
The main jets are mostly for midrange on up but are not the main fuel flow at wide open throttle.
The power valves are for any time the engine is under heavy load. ( getting on plane and wide open throttle)
And there are many other adjustments that can me made.
Last edited by Tinkerer; 05-27-2019 at 05:49 PM.
05-27-2019, 05:46 PM
#4
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As evident by the starboard motor, I’m still on the rich side, I didn’t change the jets too drastically.
The fact that the plugs are firing but are absolutely clean is something new to me.
Compression test will be this week, but I feel it may be electrical? Bad coil? Bad distributor?
05-27-2019, 05:52 PM
#7
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You idled so you don’t know if it’s rich at speed. 95 to 89 is pretty drastic. I’ve ever only went 2 at a time and it made over a full point difference in afrs. Spark is easy to check with no real tools. You can check each wire individually and the coil.
05-27-2019, 06:10 PM
#8
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dumb question but does this boat have one fuel tank or two? if they are pulling off different tanks you could have a lot of water in the tank as you said they looked like they had water on them.
05-27-2019, 07:23 PM
#9
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Holley lists this carb as having 71 primary and 85 secondary.
I was debating the staggered jetting to match the HP500 setup, but opted to keep it even each side, still bigger jets than stock Holley.
Never went WOT, as I was just feeling her out. Everything was solid until I pulled into the marina at idle. RPMs matched all cruise speeds and no obvious sign of issue until idled in at 4mph.
05-27-2019, 07:24 PM
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