yamaha F40 intermittent starting problem

[basses]

I have a 1999 f40 with an intermittent starting problem that goes something like this.
I turn the key and the engine starts but i get the whirring sound of an electric motor (fuel pump perhaps) coming from the engine.
If i leave the engine on this noise continues for 3 or 4 minutes then shuts off and the engine operates normally.
If however i shut the engine off while this electric motor is on then the engine will not restart until the electric motor has switched off.
Does anyone have any idea of what this electric motor is and why its coming on?

 

[rodbolt]

Re: yamaha F40 intermittent starting problem

the 99 F40 was a mercury design,carburated and had NO electric pumps.
either the starter relay is sticking or the power trim is trying to activate.
with the hood off start the engine and see if the starter motor quits turning when the engine starts and the key is released.

 

[basses]

Re: yamaha F40 intermittent starting problem

Thanks for your help.
The problem with observing this fault is that it's very intermittent, happens about once in every 10hrs of operation.
It's not the trim motor, i'd recognise that sound.
If as you say the only other electric motor is the starter then the problem must lie there.
Do you have any suggestions for a fix?

 

[rodbolt]

Re: yamaha F40 intermittent starting problem

suggestions for a fix?
find out if its the starter motor continuing to run after the key is released,if it is then either the starter relay is failing or the keyswitch is failing.
remember ALL the electrical parts,except the main 10 pin harness, on the powerhead are merc not yamaha.
they can be had from either place.
double check all your battery cables/connections.
use a voltage drop test on each cable.
low voltage can cause the starter relay contacts to stick.