Extremely Rich at Idle

[DEcosse]

Looking for some feedback on a VP engine performance on a non-Cobalt. I've only been here a short time but already impressed with the knowledge here on our board! So this is really a VP question rather than a 'Regal' question.
My good friend and neighbour has a 2020 Regal LS2 with the VP V6 280.
He purchased it at end of last year with about 100 hrs and it was simply parked over the winter until this season started (which was quite late this year!)
From the first outing I suggested it was noticeably incredibly Rich at idle, not just when first started - engine cold - (although probably worse, which is understandable) - still very much so however even when warmed up.
i.e. VERY strong smell of unburned gas.
It starts readily and performance is really good though (it might be a bit 'thirsty' - on a day outing it used about same amount of gas as my 8.1 V8)
It has consistently been this way throughout the season.
Our other friend was out with them yesterday and when she heard us talking about it last night she said "Oh yeah! I noticed that too!"

So - just looking for some feedback from others with this engine config - are "they all like that" ? (My understanding is some CS22's have this same engine?)
Or is this a signature of a fueling issue?

[cmattj]

Looking for some feedback on a VP engine performance on a non-Cobalt.
i.e. VERY strong smell of unburned gas.
It starts readily and performance is really good

As idle can bring odors from fuel tank vents… lines.. leaking injectors etc. it’s best to have your friend take it in and have it inspected .
This odor may be coming from engine area vents.

Sure all calibrations for marine loads are richer through the Rpm scale but with Y pipe exhaust it filters through the water.
Although soot deposits and signs of rich can be seen , your likely not to get a strong fuel odor.

Blower Fan Blower fan until it checked.

[billk2632]

Could be several things, with a fuel injected engine the two main things that control fuel mix at idle are the Idle Air Control (IAC) and the cold start sensor. It is normal for an engine to run "rich" on a cold start, but the fuel mix should lean out as the engine warms up. A sheen on the water at cold start is a good indication it is running too rich. If your friend is somewhat mechanical, I would start with two things:

1. Clean the flame arrestor - this would be comparable to a dirty air filter in a car and can affect the fuel mix, especially at idle.
2. Pull the spark plugs to see if they indicate the engine running rich - this could point to a number of things like clogged injectors etc.
3. If any of the spark plugs looks wet/smell of gas, check that cylinder to make sure it is firing - if one is not, this should lead you to check out the distributor cap/rotor etc.

Past the above, you probably need a Volvo tech to hook up a scan tool to find out what is going on.

[DEcosse]

Thanks @cmattj - I've been stressing the blower because of the situation, although he is already extremely automatic in this regard.
It's definitely when running, from exhaust, it's not a liquid leak.
I probably need to go back & re-validate the hot vs cold condition - obviously most conscious of it when it's first put in the water and started; then we tend to 'float' after riding for a while, so another cold start later - but at the end of runs, when it's hot, I'm not sure if my mind is 100% accurate on that. For sure, it seems excessive when cold though.

@billk2632 - also thankyou for suggestions
The flame arrester check is a good and simple one and we'll inspect the plugs. Although the O2 sensors should certainly trim for any lower air availability - and it runs extremely well at full power, so I can't see it being light on air.
Haven't been distributors on EFI engines in eons though

I am actually very knowledgeable about EFI systems - I even do my own mapping modifications on my motorcycle and have a wideband O2 sensor installed for monitoring. So I recognize all the factors that could possibly contribute. My lack of a frame of reference is a hinder however and hoping for some input from an owner with this series of engine, for a comparison point. i.e. is this typical for this series or do we have a genuine problem.
My other thoughts re possible hardware issues would be the thermostat (and the engine running too cold) and in the same train of thought, the coolant sensor. A lower engine temp would definitely enrich it.
We'll bring it up to temp in the driveway and see if/how it changes.

[bruceb58]

I am actually very knowledgeable about EFI systems - I even do my own mapping modifications on my motorcycle and have a wideband O2 sensor installed for monitoring. So I recognize all the factors that could possibly contribute. My lack of a frame of reference is a hinder however and hoping for some input from an owner with this series of engine, for a comparison point. i.e. is this typical for this series or do we have a genuine problem.
My other thoughts re possible hardware issues would be the thermostat (and the engine running too cold) and in the same train of thought, the coolant sensor. A lower engine temp would definitely enrich it.
We'll bring it up to temp in the driveway and see if/how it changes.

This is why I own a Rinda scanner.

https://www.rinda.com/marine/diacommarine.htm

Since these are not closed loop EFI systems, You will likely be running richer than a closed loop system until the engine warms up.