Loss of power after changing my 1997 115hp Johnson lower unit onto my 1989 90hp Johnson

[Dani1989]

I had swapped lower units as the gear case was shot as the boat would just sit there in forward gear and grinding occurred. After I swapped the lower units I took it on the lake and lost power like most of the power.

On another note I have an issue with a collapsing bulb due to a gas jockey forgetting my gas cap and having me to replace the gas unit assembly because mine was so old could not find the correct gas cap. And ever since I been dealing with a collapsing bulb. (Could this be a reason to the loss of power?)

Also the shaft with the teeth on the lower unit installed is smaller by very little (not sure if the lower units were compatible) but once I removed I installed and it seemed to fit very well.

 

[fitz73222]

Run the engine without the gascap and see if the flat bulb goes away; not venting properly.

 

[Dani1989]

Opened the gas cap when running. It stayed down. When I’m neutral and not going forward it will go back to normal.

 

[OzarkMike]

clogged pickup in the tank or the inside of the hose probably the hose has become rotten inside and has blocked its self if i had to guess. the primer bulb should not collapse only under a vacuum will it collapse and it should never be under said vacuum

 

[Dani1989]

clogged pickup in the tank or the inside of the hose probably the hose has become rotten inside and has blocked its self if i had to guess. the primer bulb should not collapse only under a vacuum will it collapse and it should never be under said vacuum

Thank you ! I will check on those.