Fixed it till it broke

C

cnollego

Member
Sep 8, 2022
83
Boat Info
2003, 220 Sundeck
Engines
5.0 MPI, Alpha Drive
My wife like to tell me to leave stuff alone...but i just can't. 2003 220SD with 5.0 MPI 288hrs. Recently changed the following:

Wires and Plugs - Original
Cap and Rotor - Original
Serpentine Belt - Original
Thermostat - Original
IAC - Muffler - Dirty Original
Throttle Plate and Throat - Cleaned

Now mind you, the boat ran fantastic for the past two years that i've owned it and has never given me even a little bit of trouble related to these issues.

Went out and started the boat after all these PMs were done and she ran great. Coming back into the marina, 1 beep and the engine would stumble, not die, just almost. Did this a few time heading to the slip.

Looked all over, no issues found with anything above. Temp 170, Oil 40, RPM 600 and steady while idling at the slip. Then a beep, and died. Kept doing this even after i wiggled wire connectors, checked HEI boots...nothing.

Decided based on research to check the IAC by Ohm it out. Went to pull it off the spacer block and thought I didn't have the right hex wrench as it just spun...it's dark back there.

Come to find out it, my wrench was seated it was that both IAC hex bolts were loose...like real loose. So i pulled it off, looks very clean, Ohm'd out at 10.3 which is in spec. so it was reinstalled with some blue Loctite and tightened down properly.

Guess what. No more beep/stumble on idle. I can only surmise that while i was doing all this work and leaning on the spark arrestor/IAC bracket it may have caused the already loose bolts to become more loose.

And, before i found the loose bolts on the IAC, i ordered a VVM to go on so i can gain a little more insight to what the boat is telling me. I'll post a follow up with any stored codes...hopefully they correspond to a vacuum leak which I think was the culprit.
 
Fixing it until it’s broken is the story of my boating life
 
I'd call that sensible preventive maintenance. All of those items at 20yrs old are due for a replacement even if the hours don't suggest it.

If it makes you feel better about forgetting to tighten bolts, I ended up doing a full top-end rebuild on my engines last season while in the water. Not a small job, and it turns out I forgot to reattach one of the dipstick tubes to its little J clip on the manifold. The consequence was that the dipstick tube was loose where it connected to the banjo fitting at the base of the oil pan, so all the oil dripped out of the engine over winter. That was fun to find when I got under the covers a few weeks ago. This is despite me being careful photographing everything and making a log of what I've done. Shit happens.
 
Boating rule #1 - You can never have 100% of your boat working at the same time. The minute you fix the very "last" thing that is broken, something else breaks that you don't know about yet.
 
skibum said:
Boating rule #1 - You can never have 100% of your boat working at the same time. The minute you fix the very "last" thing that is broken, something else breaks that you don't know about yet.
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+1. I always assume everything on my boat is in some stage of breaking.
 
Flyer5 said:
Defines anything mechanical. Difference is when it Flys, Floats or F@##s, it gets more expensive.
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My neighbor went to the Naval academy and flew F-14s for 10 years. Every time my boat comes up he tells me "if it floats, flies of f@cks rent don't buy". Well, except when his wife is there, then he doesn't say anything...
 
highslice said:
My neighbor went to the Naval academy and flew F-14s for 10 years. Every time my boat comes up he tells me "if it floats, flies of f@cks rent don't buy". Well, except when his wife is there, then he doesn't say anything...
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Next time she is with him, ask him to remind you of that saying. :) I bet he will never bring it up again.
 
well, the quick beep and dies when idling in the marina is back. Starts fine, runs great, just when i'm at idle in N or no wake through the harbor, quick "beep" and she dies.

VVM is on order so it will be interesting to see what codes she's throwing. I'll report back with finding in a few weeks once I'm back on the water.
 
cnollego said:
well, the quick beep and dies when idling in the marina is back. Starts fine, runs great, just when i'm at idle in N or no wake through the harbor, quick "beep" and she dies.

VVM is on order so it will be interesting to see what codes she's throwing. I'll report back with finding in a few weeks once I'm back on the water.
Click to expand...
Did you replace the IAC valve?
 
Well, I always respond with this fix when I had a similar problem, but it never turns out. I have a 5.0MPI similar to yours.

I had a similar issue. Idles fine, but the minute the motor was under load, it would beep, stall, and restart. I replaced the IAC and that wasn't the cause. I replaced a non-refundable ECM at $2K, that wasn't the cause and actually made it worse. I had no codes. The marina couldn't find anything on their scanner.

Turns out it was a $70 part at NAPA. The Crankshaft Position Sensor. Mercruiser finally added a code for it I believe in 2007. It's at the front, bottom of the block/crank shaft. It sends a timing signal to the computer. It's just a magnet that senses a lobe for timing. For some reason I can't find it in the parts catalog. Should be two wires with a plug. One bolt to take the sensor out. It's GM sensor.
 
Nice to know that. VVM was installed and you guessed it...just the 4 codes for missing sensor inputs that everyone describes and blocks. However, it hasn't done the beep/stop since VVM was installed. Would think if it had a code it would have stored it no?

I will keep the CPS in mind if she starts doing it with no codes.
 
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