The carb is a Holley 800cfm dp like the 9022.

There is a primary powervalve, no secondary one.
Here is mercruisers parts list on it;
https://www.mercruiserparts.com/bam/...13459/28183947

Is there a good alternative to the stock mechanical fuel pump or is 861677T the best out there?

My bad, wasn't aware Holley made DP's without secondary power valves.

Airtex 60932
Carter M60932
Sierra 18-8860

An oso member or two stated their merc pumps where airtex. I can’t vouch for it, but a search will find those threads. Lots of threads on these tears ago.

I just checked the Quickfuel 850 DP I got used. It doesn't have a PV in the Sec metering block either.

Good to know. I was planning on upgrading to Quickfuel carbs someday.

With no PV, the needle/seat assy is abt all I can think of that would cause secondaries to flood. (Assuming the fuel pressure hasn't increased somehow).

I've seen shards of Teflon tape get tangled with fuel pump check valves preventing them from sealing. If any fuel line fittings got taped recently, shards could prevent a needle/seat assy from sealing.

New fuel pump will be here today so will let yall know. I talked to a few who have said they have had pumps go bad by increasing psi. Only thing I can think of at this point. We shall see.

Have you put a new o-ring on the needle body? In my experience that is the #1 cause of flooding like your experiencing. Also you MUST lubricate that o-ring when screwing the body into the fuel bowl. If you don't, odds are very high that you will tear it and be right back where you started.
When rebuilding the Merc 500 carbs remember that they have a funky metering jet layout on the. Put the jets in the wrong corners and your going to have lean/rich issues.
As for power valves on the secondary side of a 4150/4500, they are primarily used in carbs intended to be used on street cars. True high performance carbs rarely have them on the secondary side. Some race only carbs won't even have them on the primary side.

Update:

Im embarrassed to even update this but maybe it will help someone in the future. While at Jegs I was talking to my salesman and had the float in my hand. I looked down at it for whatever reason and saw a super tiny air bubble move around. Needless to say it was so full of fuel I couldnt even tell without seeing that bubble. I guess if someone was familiar with carbs they could tell by the weight of the float but honestly it wasnt much difference. Either way a new nitrile float and back together and its good to go. Well other than a new outdrive issue but thats another topic for another day....lol. Thanks again for all help! And yes I know it was mentioned on here about the float. I just couldnt see it until I saw that air bubble.

Thanks!

Chris

Thanks for the update. Nice to know the solution for future reference.