1978 Johnson dies

[bank10]

I bought a boat and a 1978 Johnson 15hp motor from a boat mechanic off ebay.

I took it out and it started on the second pull, but when I ran the throttle up it died.

I trolled for over 3 hours, but could not get it to run over 7 miles an hour.

Any help is appreciated Dave.

1978 Johnson model number is, 15r78b

 

[Vic.S]

running on one cylinder perhaps... check

check sparks and plugs

check compressions

If sparks , plugs and compressions good then maybe carb requires cleaning.
does bit of choke help at all?

what sort of boat? I'd not expect mine to go as fast as 7mph.

 

[boobie]

Do a cylinder drop test on it.