Electrical issue questions - 1990 4.3 alpha 1 , gen 1

We took the boat out yesterday for a shake down cruise and a bit of fishing too. I had just changed the oil, new bilge pump , and did some other maintenance including getting my “get me home” outboard mounted on a new adjustable lift plate. BTW....THAT thing is nice!

So anyway we get in the water and and go to fire up the main motor, and get nothing but a click. Sounded like the started started to engage, but not enough juice to turn it over..... I’m thinking I ran the bilge pump too much, and used that electric dip stick pump to change the oil, and just ran the batteries down to low...of course I left my multi meter at home...

So I had a NAPA auto parts store real close, and just bought a new Marine grade battery, (That left a mark).... got it switched out, and the same story.... nothing but a starter click.... so I had my wife change the batter selector around to the 2nd battery and nothing there either. Then switched it to all, and bingo! She fires right up.... that was weird....but wait! There’s more!

After idling out away from the dock far enough I ran the throttle up to run down river and she was really running bow high, so I hit the trim button on the control to bring it down, and the engine acted like I’d cut the power to it and tried to stall out every time I hit the trim button.... I never did get it up on plane. Had to throttle back down. At lower rpms I hit the trim button again and it killed the engine.

tried to start it back up..... and I’m back to square one again.... nothing but the starter click again. So I had my wife flip the battery selector switch around from 1 to 2 and then back to all, and bingo! She fires back up again.... this time I try the trim switches and everything is working fine.... no problems the rest of our trip. Probably put two hours on it, no more issues.....

So it seems quite obvious that I have an issue with the battery selector switch not functioning correctly.
or maybe not?

but.... Having the trim button killing the motor is still bothering me.... I mean this has nothing to do with my ignition system. Those switches should be powering the hydronic pump only..... The fact that it just started working correctly again after switching the selector switch doesn’t make any sense to me....

any ideas on how I can trouble shoot this so I’m not dead in the water again? Thanks ....Kirk

Try the simple things first. Check all the connections on all the battery cables to ensure they're all tight and clean of corrosion. Check the negative cables too.
Low voltage can make all kinds of weird things happen. If this doesn't help then get back to us.
Without a multimeter or voltmeter you are flying blind regarding troubleshooting. Even something like these cheap USB charging outlets come with a voltmeter so there's that if you don't wanna pay $50 for a dash gauge.

Check the slave solenoid. More common issue than you know.

RE: "Also, if you have an old Perko MBSS (main battery selector switch), and in particular the 90* sweep style, they have rather weak spring pressure and rather light duty contacts. It is possible that the MBSS is not delivering full continuity. "


I've changed all my boats and the ones I maintain over to Blue Sea MBSS.... cheaper and better built. Never have had one fail in numerous boats over 15 years,whereas I've seen several of the PERKO ones either fail outright or get "funky".

https://www.bluesea.com/products/9001e/e-Series_Selector_Battery_Switch

Thanks guys. I ordered another selector switch and will get that all cleaned up.

but.... it still doesn’t answer my question regarding why the electric trim switch would stall out the engine? That is just too weird. Kirk

Trim pumps can draw a significant amount of current - I've seen over 40 amps....If you wiring isn't in decent shape, that current draw will induce a voltage drop...and stalling is one by product...

..... and poor contacts in the MBSS will also cause a voltage drop.