1978 thunderbolt tower of power won't go faster than idle speeds

[Bass_o_matic]

Took the boat out before and opened it up...did about 40-50. Next time I took it out it was having issues getting faster than idle speed, however all at once things clicked and we went flying. Today it would never pick up speed whenever the throttle was opened up. It would idle high, but when I popped it into gear it would get weak and want to die. A little more info. It would fire up on command every time. Just had a boat shop clear up some carb issues (that's another thread in itself). When I picked it up he said he though there was a cable issue in the throttle box, however I opened hIt up and things seam to be working how they should. Any thoughts?

 

[Luckymann77]

Had experience with a worn out throttle cable...
Cheap and easy enough to replace although that may not be your only issue.

Have heard of a backwash of water during deceleration allowing water to get into the tank via the tank vent...
I would drain as much of the tank as I could and start with some fresh fuel and add Seafoam, no more that 8 gallons.
It'll probably smoke a bit more that usual for that tank, but that's the Seafoam working.
Cleans carbon and dries the fuel...good stuff !

 

[Bass_o_matic]

Is there a way to determine how long a control cable to buy, or do I just need to pull the current one?

 

[Chris1956]

Control cables usually have the length stamped on them.

Are you sure the idle mixture is set properly. If set too lean (and sometimes mechanics do not know this), she will die when the throttle is opened.