A rather strange engine problem

[Shaneesprit]

Originally Posted by JoeRobertJr

I'd start by checking (and cleaning) the starter solenoid connections. If the problem persists, then check for voltage at the starter solenoid control wire when you turn the key.

That’s what I would go for - not strange at all - prefect symptoms of a bad starter solenoid.

[Kettlewell]

First thing to try is cleaning and tightening the battery cable connections to the solenoid and the starter. I went through all sorts of stuff trying to fix a similar problem and it turned out to be corroded and loose connections to the battery.

[NNBill]

I have some experience with the Nanni/Toyota marine engine no crank issue. The three issues that I found where (1) Defective ignition switch, (2) Green crusties in and around the axillary start relay back by the bell housing, and (3) Corroded wires at the crimp terminals on the neutral safety switch on the side of the Borg Warner Velvet drive transmission. This was on two engines in one boat over a 5 year period.

[rpackard]

If you don't even hear the solenoid click when you hit the start it is probably the neutral switch mounted on your transmission. You may not be placing the shift lever never exactly into neutral. Jiggle the shift lever when trying to start.

[Henryh]

I have two Nanni 3.21 engines 2007 vintage. The wiring loom is NOT tinned wire and the connectors in the loom are old type unsealed automotive. Rather ridiculous for a marine engine. I had a similar problem and the cause was the rather thin wire that goes to the solenoid was corroded. I had to run a new wire to the solenoid. Of course it was the engine furtherest from the engine controls.
Could be worth checking.