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From the Sea Ray Boater's forum: The IAC valve regulates the air flow at low RPM's or idle by bypassing the throttle plate thus allowing the engine to operate at the low rpms which you need to do on fuel injector engines. "So and So" carries a spare IAC VALVE with him at all times....
I thought I would buy a newer boat thinking the technology is better:
My 2013 MerCruiser 377 Mag EFI engine encountered problems upon startup half way through the season. I couldn't get it to warm up without physically hand holding the throttle to keep it running. Once it warmed up I could drive the boat fine but the idle was very low and seemed like it would stall out, but it didn't . It got right up on plane and ran great but when I put it in neutral it ran around 350 rpms. Earlier in the year, I got an Engine Misfire light that never went away. I though I found a loose spark plug wire and pushed it back on but the warning stayed on. Apparently a dealer with the Mercury $6,000 diagnostic software package can diagnose the cause, repair it and re-set the computer.
I called Mercury, bought a service manual, watched U-Tube Videos, bought a new distributor cap and rotor, bought and replaced the "Cool Fuel" paper filter inside the canister, found out a pancake filter underneath the canister was never replaced and not listed in the service manual, so I replaced that and replaced the IAC filter, some call it a slinger and others call it a muffler. The IAC filter is a 1" x 1" x 1/2" piece of foam that inserts into the throttle body and costs $10. I also toted 14 gallons of rec fuel and added Stabil to it thinking maybe I had bad gas. Since it jumped right up on plane, It couldn't be bad gas, could it? All in all, it cost me $500 and the problem was still there.
Since it was the end of the season and since my dealer was going to pull the drive off and service the drive ($400) and winterize and shrink wrap the boat ($473), I reluctantly asked them to check out the stalling problem. They diagnosed and replaced the faulty IAC valve ($187) , added spark plug wires ($145) , replaced spark plugs ($156) , diagnosed it on the computer and determined it was fixed ($625 labor). All of this work came at a hefty price on top of the $500 I spent getting no where. I could have done the spark plugs and wires, but they had me hooked... I had a weird noise, like a howl, that the mechanic said was the fuel pump and it's normal. Maybe the low idle played a part in the FP howl...Thank goodness the fuel pump wasn't bad.
I had older boats with carburetors and all of this PCM (power control module) and fuel injected technology is new to me. Is it possible to work on your own boat if its a computer guided engine? Everything is sensored, labeled and coded in the Power Control Module to shut the engine down if something goes wrong or give you a warning. All I could do is throw a bunch of parts at it, but now i realize i went down the wrong path...
I am hoping this helps someone who may have the same problem and they don't waste a bunch of dough like i did..
I thought I would buy a newer boat thinking the technology is better:
My 2013 MerCruiser 377 Mag EFI engine encountered problems upon startup half way through the season. I couldn't get it to warm up without physically hand holding the throttle to keep it running. Once it warmed up I could drive the boat fine but the idle was very low and seemed like it would stall out, but it didn't . It got right up on plane and ran great but when I put it in neutral it ran around 350 rpms. Earlier in the year, I got an Engine Misfire light that never went away. I though I found a loose spark plug wire and pushed it back on but the warning stayed on. Apparently a dealer with the Mercury $6,000 diagnostic software package can diagnose the cause, repair it and re-set the computer.
I called Mercury, bought a service manual, watched U-Tube Videos, bought a new distributor cap and rotor, bought and replaced the "Cool Fuel" paper filter inside the canister, found out a pancake filter underneath the canister was never replaced and not listed in the service manual, so I replaced that and replaced the IAC filter, some call it a slinger and others call it a muffler. The IAC filter is a 1" x 1" x 1/2" piece of foam that inserts into the throttle body and costs $10. I also toted 14 gallons of rec fuel and added Stabil to it thinking maybe I had bad gas. Since it jumped right up on plane, It couldn't be bad gas, could it? All in all, it cost me $500 and the problem was still there.
Since it was the end of the season and since my dealer was going to pull the drive off and service the drive ($400) and winterize and shrink wrap the boat ($473), I reluctantly asked them to check out the stalling problem. They diagnosed and replaced the faulty IAC valve ($187) , added spark plug wires ($145) , replaced spark plugs ($156) , diagnosed it on the computer and determined it was fixed ($625 labor). All of this work came at a hefty price on top of the $500 I spent getting no where. I could have done the spark plugs and wires, but they had me hooked... I had a weird noise, like a howl, that the mechanic said was the fuel pump and it's normal. Maybe the low idle played a part in the FP howl...Thank goodness the fuel pump wasn't bad.
I had older boats with carburetors and all of this PCM (power control module) and fuel injected technology is new to me. Is it possible to work on your own boat if its a computer guided engine? Everything is sensored, labeled and coded in the Power Control Module to shut the engine down if something goes wrong or give you a warning. All I could do is throw a bunch of parts at it, but now i realize i went down the wrong path...
I am hoping this helps someone who may have the same problem and they don't waste a bunch of dough like i did..