2005 Mariner 30HP EFI 30PT4S to 40HP?


New member

I have a 2005 Mariner 30HP EFI 30PT4S with about 400hrs on the counter.
It is mounted on the back of a old originally build in 1971 speedboat which I converted to a console boat.

The max speed I reach is about 50km/hr (27 knots) when I`m alone.

For the water sports, like fun tube, knee board and coming season wakeboard I like to have some more power.
According the 30/40 4-Stroke manual the 30 and 40hp versions seems the same, but are they?

Is it possible to upgrade my 30HP 30PT4S to a 40HP version by maybe only changing the ECU? Or is there more there have to be done (besides a prop change).

Is there maybe someone who can tell me if it is possible, and what there needs to be changed, and if possible are there maybe some disadvantages by doing this.

Thanks for your reply`s.

Best regards,


Advanced Contributor
Open up the parts catalogs for each of the models in question. Compare the part numbers for differences. Remove the 30 HP peculiar parts and then install the 40 HP peculiar parts.