Sea water flow?
 

1994 Merc. 454 Mag. Bravo 1. Problem.
Very little water coming in and out. Impeller is new. With the hose, (under preassure) water flow is good. Interior of block seems ok, since there is good flow in and out with hose, Even after the impeller housing when I hook the hose up passed the impeller. Intake hose is OK, no crimps. etc. I can blow air out at the hose when intake goes to the impeler, no ristriction. OK so.. Where could I have a leak, or having no "vacum" to the impeller. I think it might just be sucking air, even when outdrive is submerged. Any thought?
THx
P

Try switching your in/out hoses at the pump.
I replaced my impeller and SWORE I put the hoses back on the same way, but somehow I had it backwards.

Tried it both ways. Pump housing is marked pretty straight forward as in and out.

you have a soft hose Pete?? under the hose, the pump has to suck less. Without the boost from the hose the suction would be greater collapsing a hose and reducing flow. Check the hose from the helmet to the gimble too.

Transom shield water fitting can crack it is reinforced plastic.

All hoses are good, rigid, etc. I have to remove the drive and see if there is something at the outside/inner connection. I ran out of ideas.
The connection at the inner transom plate is good.

Fixx
 

theirs a in and out on both hose nipples at the back og the seapump housing..in/out on one and in/out on the other.....if you run in salt the area between the outter hose and the inner fitting gets plugged up ,,that section is small..try taking the inside fitting off and you may see a build up of corrosion..

THanks. No corrosion. Like I said, the system works when I hook up a hose direct to the inlet at the impeller housing. I got to be sucking air at the drive. But where? I know how it looks nside, and I can think of anyplace that there might be air getting in. Especially when the hole thing is submerged.

I struggled a bit with this last month. I verified I had no air leak by putting duct tape over the holes at the bottom of my Bravo 1. I was able to suck on the pump inlet hose and create a vacuum. I also stuck a garden hose into the pump inlet hose to make sure all the hose water came out the holes. Free flowing and no air leaks.

When was the last time you changed the molded hose that goes from the helmet to the inner transom assy? The fitting where the molded hose attaches to the inner transom is prone to corrosion. Only way to see it is by removing the hard hose housing at the transom inside the boat. I would start by replacing that. Another thing I have seen, though not as common, is the hard hose delaminating inside. The water gets under a layer and collapses the hose internally starving the pump of flow.