4.3 MPI extra wires behind TB and water flow question

[505callyourball]

Found these today and I'm very curious as to what they're for. The don't seem to be marked like they've ever been attached before. They reside under what I believe to be the "computer". Any help is appreciated!
SN# 2A053495 in a '13 Tahoe 19'

I also do not know what this is...to the right of the TB

Lastly, I've not found a definitive answer regarding Alpha1 Gen2 water flow. On muffs I have good flow from transom holes but nothing really from the prop. Once warm there is some steam from the prop but no actual water. Engine temp has not been an issue, I just don't know what I should be seeing. To add to that, how would one tell if the impeller failed being there is another pump on the engine?

Thanks again for any and all help. First post in quite some time, first boat in quite some time!

 

[Maclin]

Not sure on the wiring questions.

On the water flow question, at idle or just above most of the water exits out the idle relief ports on the bottom of the transom. There should be some that runs out the bottom of the prop hub at faster idle. I usually get some flow out the prop even with the main flow out the relief ports. Steam does not seem like a good sign.

The "other" water pump on the engine is only a circulating pump for the cooling system in the engine. It only circulates the water that the raw water pump in the outdrive provides. It cannot draw water in.

 

[achris]

When running slower (idle and 'off idle') most of the water from the engine runs down the Y-pipe and into the relief holes at the bottom. Very little gets into the main exhaust flow, so you will see very little water from the prop. Once the engine and the exhaust passages in the drive heat up, which is normal, then you will see some steam, not too much... But that is also normal...

Chris......

 

[505callyourball]

Thank you both for the reply, I feel much better. Hopefully a wire guru will chime in too...

 

[505callyourball]

It only circulates the water that the raw water pump in the outdrive provides. It cannot draw water in.

With this being the case, if the the impeller were to fail, then I would not have any "pee" correct?

 

[Maclin]

There is no pee hole to look at as in an outboard. But you would not get good water flow out the transom relief holes if the impeller in the drive is compromised. Water gets pushed by the impeller to the engine then out the exhaust, so when you see the water coming out the exhaust it has made it all the way from the muffs thru the engine and out the exhaust.

 

[Fun Times]

The 3 wires look to be for the MerCathode corrosion monitoring system that is an option on Alpha stern drives and standard on Bravos drives. Hard to make out but one of those wires looks orangish colored correct? Image search part number 98869A17 online..... Item number 14 in the following link, http://www.mercruiserparts.com/bam/s...31509/15417/40
The wires are fine/safe to be untapped/not covered up power wise like that.

The other item in question is called an IAC filter that needs cleaning at the very least but should be replaced...Item number 11 in the following link, http://www.mercruiserparts.com/bam/s...31509/15417/90

http://www.mercruiserparts.com/4-3l-...ec-1a637496-up

 

[505callyourball]

Thanks Maclin and FT. I’m in the unenviable position of reassembling something I did not take apart. So far so good though. After cleaning the little filter I should be finished with the top...

 

[Maclin]

Thanks for clarifying, I was curious as to why you were into it that deep.