Won't start

[Russ Calasant]

I did a quick search and did not find anything so here it is- boat launched Thursday, port motor was running a little rough but after warm up it smoothed out, almost like initially it was not running on all cylinders. But both motors started right up and ran to the slip. Now on Sunday I attempted to start both engines, turned on blower, master ignition- keys and panel switches. Flipped port dash toggle waited for alarm and depressed to engage starter and nothing. Tried starboard and nothing their either. Checked shift location, all breakers, battery switches and engine compartment including voltage, all good. Tried starboard again this time pressing the emergency start toggle and then the starter engaged. Stopped and started several times without issue. Port will still not engage, no noise (solenoid) at all just dead switch except for alarm even when I press emergency start. Any thoughts or ideas would be helpful, thanks. 1997 7.4 Merc 696 hours MPI that have been flawless.

 

[Stray Cat]

Have you cleaned your all of your battery terminal connections? Start at the batteries and work your way toward the solenoid & starter connections.

 

[fwebster]

Since the engine started numerous times, its a reasonable guess that the batteries are in at least decent shape. Check the voltage thru the starter slave solenoids. Frequently after layup or period of inactivity, the slave solenoids will fail, I suspect because of a little corrosion on the contacts. Using the emergency start solenoid increases the amperage and that extra uuumph is sometimes enough to arc thru the corrosion. Your boat is an '07, so its about time for them to say "Hi- replace me!" The slave solenoids are a $16 part and it takes 10 minutes to change them.

 

[Jimmy Buoy]

I had similar symtoms a couple of years ago. Ended up being an issue of bad ground on the engine's main ground connection. That's the spot on the engine with a large bolt with mutiple black battery cable size wires attached. In my case, it even appeared ok, but after taking it off, cleaning, and reinstalling, the problem has not ever happened again.

 

[Russ Calasant]

Thanks guys- all very helpful. Frank, how do I measure the voltage? Is the slave solenoid sitting on the starter with the battery cable going to it? Or is it mounted on the bulkhead? Which terminals should I be measuring and what should the voltage be? Sorry for the ignorance, want to be sure.

 

[Russ Calasant]

Frank- I found it and jumped the yellow and red with 12 v and it cranked away. What do I look at next? 12v is at the switch when I press the toggle but it's not at the slave solenoid? What is in between that could be stopping it?

 

[BonBini]

Frank- I found it and jumped the yellow and red with 12 v and it cranked away. What do I look at next? 12v is at the switch when I press the toggle but it's not at the slave solenoid? What is in between that could be stopping it?

Russ: Between the start switch and the slave sol would be the neutral safety switch. However things are starting to get inconsistent with problem #1 "both engines would not crank unless emergency start toggle used" I'm suspecting a few faulty connections going on here.

1)... You could try sticking with one problem without disturbing things. pinpoint your diagnostics to find the exact location in the circuit where the problem exists.

2)... You could start unplugging connections for a visual inspection and cleaning.

if it were me: I believe I would pull some maintenance on connections just to get a feel for the condition of the overall wiring. jm 0.02.

 

[Russ Calasant]

Thanks Ron, I am not so sure the emergency start had anything to do with it- may have been a coincidence. The connections and condition of the wiring all look really good, almost too good for it's age, very well taken care of. I appreciate your input. My concern at this point is that I have been unable to duplicate the issue.