Power surge - Cap and Rotor replacement

Canada96 · August 20, 2020

Hi,

Long story short this past winter was the first winter we kept the boat (08 Falcon V Air Warrior with the 350 mag mpi) outdoors instead of in the shed and now we are having some power surging issues.

The boat runs good, not perfect, but good when pulling a wakeboard, but when we went to load the sacks full of weight and start surfing we began to notice power surges. Almost to the point where it seemed like a transmission slipping in a car. Now I am hopeful this is a power issue and not a v-drive issue, so I have decided to start with swapping a new fuel filter on, cap and rotor and take it for a test run. I'm not sure when, if at all the cap and rotor has ever been changed so I'm sure its not going to hurt anything.

Now I had a few questions for the cap and rotor replacement:

1. What is the suggest replacement? Marine or will automotive be fine? OEM/Aftermarket?

2. When changing can i simply pull the cap off, swap plug wires 1 by 1 to the new cap, and than pull the rotor off and slip the new one one and reinstall the cap without running into timing issues?

3. Should i be looking at anything else while the cap and rotor are off the shaft?

4. Any other suggestions for diagnosing the surging issue? Next will be new plugs, which I anticipate I will replace anyways.

Thanks

volzalum · August 20, 2020

17 hours ago, Canada96 said:

1. What is the suggest replacement? Marine or will automotive be fine? OEM/Aftermarket?

2. When changing can i simply pull the cap off, swap plug wires 1 by 1 to the new cap, and than pull the rotor off and slip the new one one and reinstall the cap without running into timing issues?

3. Should i be looking at anything else while the cap and rotor are off the shaft?

4. Any other suggestions for diagnosing the surging issue? Next will be new plugs, which I anticipate I will replace anyways.

1.If I recall correctly from my last boat, the marine version had better corrosion resistance than the automotive one

2. No timing issues if you get the wires installed the same as the old one

3. Look at IAC valve also

4. Verify you do not have any water in the gas. When loaded, the water would all come to the back and is where the fuel pickup is, so may only be enough when loaded out to cause an issue.

Canada96 · August 21, 2020

6 hours ago, volzalum said:

1.If I recall correctly from my last boat, the marine version had better corrosion resistance than the automotive one

2. No timing issues if you get the wires installed the same as the old one

3. Look at IAC valve also

4. Verify you do not have any water in the gas. When loaded, the water would all come to the back and is where the fuel pickup is, so may only be enough when loaded out to cause an issue.

Awesome, just the reply I was looking for. Straight to the point help. Water in the fuel is a good call, as usually we have the fuel tank full before storage to reduce room for condensation through the winter but last winter we must have forgot.

InfinitySurf · August 21, 2020

I think you are on the right track, the cap is a maintenance item that can get corrosion build up on it pretty quick and my guess is this is the mostly likely thing to be giving you issues. IAC is also a great suggestion.

On the fuel side, I would definitely replace the fuel filters and when you check for water, check to see if your fuel pickup has a screen or filter on the end as sometimes they can get clogged enough to bog down the engine under load (rare but possible)

If your replacing the plugs, you should check out the wires as well to make sure they dont have cracks. You can test their resistance using a meter.... another trick is too run the engine in the dark while gently moving the plug wires, if you see any arcing, they will be an issue.

I assume you have checked the fluid levels in your trans & v-drive? From how you describe the surging, it sounds fuel related but low fluid levels can cause slipping and depending on your pitch/roll when boarding, if fluid is low that is the most likely time to have issues. It could also happen if any water got into the breather vents....so you also want to be sure the fluid is not milky looking. Some models have different procedures on how to check the fluids, some you check cold without screwing the dipstick back in (my PCM trans is like that).... others you have to shift the boat into forward, then reverse and then check it warm, etc. Probably time to replace the fluids anyway. I have a handheld vacuum canister that i use for the trans & v-drive so I can suck out the fluid, measure the amount removed and then put exactly the same amount back in (if I know the level is correct before replacing). I change out my trans fluid every layup so its an easy method to keep the level where I want it, most of these units take between 1.5 - 2quarts and usually you cannot get all the old fluid out. I started removing a quart of the transmission DEX III and putting in a new quart since I do it frequently. My v-drive is the power plus, so it takes a special synthetic fluid they call "maintenance free"... but when reading the fine print it is still supposed to be replaced every 5yrs.

Canada96 · August 21, 2020

11 hours ago, InfinitySurf said:

I think you are on the right track, the cap is a maintenance item that can get corrosion build up on it pretty quick and my guess is this is the mostly likely thing to be giving you issues. IAC is also a great suggestion.

On the fuel side, I would definitely replace the fuel filters and when you check for water, check to see if your fuel pickup has a screen or filter on the end as sometimes they can get clogged enough to bog down the engine under load (rare but possible)

If your replacing the plugs, you should check out the wires as well to make sure they dont have cracks. You can test their resistance using a meter.... another trick is too run the engine in the dark while gently moving the plug wires, if you see any arcing, they will be an issue.

I assume you have checked the fluid levels in your trans & v-drive? From how you describe the surging, it sounds fuel related but low fluid levels can cause slipping and depending on your pitch/roll when boarding, if fluid is low that is the most likely time to have issues. It could also happen if any water got into the breather vents....so you also want to be sure the fluid is not milky looking. Some models have different procedures on how to check the fluids, some you check cold without screwing the dipstick back in (my PCM trans is like that).... others you have to shift the boat into forward, then reverse and then check it warm, etc. Probably time to replace the fluids anyway. I have a handheld vacuum canister that i use for the trans & v-drive so I can suck out the fluid, measure the amount removed and then put exactly the same amount back in (if I know the level is correct before replacing). I change out my trans fluid every layup so its an easy method to keep the level where I want it, most of these units take between 1.5 - 2quarts and usually you cannot get all the old fluid out. I started removing a quart of the transmission DEX III and putting in a new quart since I do it frequently. My v-drive is the power plus, so it takes a special synthetic fluid they call "maintenance free"... but when reading the fine print it is still supposed to be replaced every 5yrs.

Thanks! More great suggestions. I will be replacing the fuel filter tonight as well as checking your guys suggestions. Hopefully get the boat on the water tomorrow for a test run and see how things go. Unfortunately we do not have a Merc dealer in my hometown so an easily accessible cap and rotor is more than likely something I will have to order. Fingers crossed its a fuel related issue and all is well, but plans are to change out the cap/rotor regardless. I never even thought to check the trans levels, but fluid was replaced either the beginning of last year or end of the year before.

Edited August 21, 2020 by Canada96

volzalum · August 22, 2020

This thread might help you ... http://www.centurioncrew.com/index.php?/forums/topic/10014-2008-black-scorpion-330hp-plug-wires-cap-and-rotor/&tab=comments#comment-130378

Canada96 · August 23, 2020

On 8/21/2020 at 9:59 PM, volzalum said:

This thread might help you ... http://www.centurioncrew.com/index.php?/forums/topic/10014-2008-black-scorpion-330hp-plug-wires-cap-and-rotor/&tab=comments#comment-130378

Unfortunately the part number seems to a be for a different distributor. I am looking for the flat cap. Thanks tho