Paul i know why you dont like the injection is because of the electronics and the water but my engine compartment / bilge doesnt see any more water than my truck does and it has way more electronics than my boat does with none of the issues that i am having now with my boat

my boat didnt start missing till this weekend , but its been slugish for a long time its a 226 baja 23' long i have been changing props like there going out of style lol steal slow only 42mph @4000rpms with a 23p 3 blade giveing it all she has! And steal can't hit the rev lim/. how fast should it go about??? and i was told most sbc have 55-60pai for fuel presure

I understand that, but also GM, Ford and Chrysler has alot more money to put into their development programs than Mercruiser will ever have. Doesnt matter if water is inside the bilge or not. You said there is none in yours, so you have proven my case...electronics and boats/water do NOT play well together. Look on any boat forum and it is endless with issues related to EFI/MPI or some sort of an electronic issue. All my friends out here that have dumped the EFI/MPI and went to carbs have no more issues and I have found that people with carb issues mess with them when they think they know what they are doing, but in reality...they dont know what they are doing resulting in screwing them up. With a carb, there isnt a whole lot of electronic crap and if your motor doesnt run right...it is either spark of gas...no sensor this or that or some BS guardian mode. Now someone is saying to check the screens on the injectors...no fuel filter?? My best bud had all sorts of off & on issues with his MPI shortly after he bought it. Now there is a carb on it and all he has done the past 2-1/2 years is change the oil, plugs and sea pump inpeller and he boats everyday "without" any issues. All up to you...I feel for ya, but you have to decide...you want to boat or sit on the trailer.

You might have some other issues as well. I would start with a compression check on the motor. But, if you want to see if it will turn anymore RPM...put a 19 inch prop on it and go run it to see what happens. If it is the same as with the 23 inch...then you DO have issues.

i really think that both of us are having the same problem and it is a fuel pump issue since i have already changed all of the electronics from my old engine to the replacement and nothing has made a difference and it just keeps getting slower which could be from the fuel pump getting worse

i did that, i stated with a 23p 3blade then a 21p 4 blade then 19p 4blade then just cause i had one a 23p 4blabe then back to the 23p 3blade all ran like ass the fastest i could get it to go on gps was 42mph i checked the compression about 2 mouths ago and had 127 in all 8 i thought that was good?

Could be a fuel pump...pull a couple of plugs and see what they look like.

127 is sorta low...160's would be alot better.

Found actual fuel pressure range to be 37 - 43 PSI 35 PSI @ idle and 33 PSI @ 2000 RPM (no load). Tech support says this is normal and spring pressure in the pumps override the electrical pump under load and pressure comes up 4-5 PSI.

i really think we both have fuel pump problems