Battery Switch

[hudsonoffice]

I have a 1998 Larson Cabrio 254 with a single 5.7

I have dual battery switch and the boat will start perfectly when switch is on #2 or both, but on #1 which is my starting battery I get a little buzz and that is it. Battery has plenty in it. I even swapped it out with a different battery just to see if any difference.
When in #1 I turn key and gauges do seem to jump up but like I said no crank at all.
Could this be a bad selector switch? How do I test to find out?
Your suggestions are greatly appreciated.

 

[ThomW]

No offense, and may seem obvious, but are you sure you have the battery switch hooked up correctly? Do you have the necessary wires hooked up to the common post, so that it can start when on either battery? If wires that need to be on the common post are connected to the #2 post, or the #2 battery itself, it would only start on #2 or both, but not on #1. If that is all correct, check your grounds and make sure a connections are tight and clean. What do you mean "gauges do seem to jump up?" Do the gauges work with switch on #1 battery? Gas gauge show reading?

 

[hudsonoffice]

No offense at all. Always have to start with basics. I am sure it is hooked up correct because it started just fine since launching this spring and I go couple times every week.. I haven't done any new wiring to boat and this started happening this week.
What I mean by the gauges jump is that when the key is turned to on position they read battery voltage gas etc. Just doesn't want to crank. I have not pulled out battery switch yet so it is possible loose or dirty behind it.

 

[ThomW]

Well, if the gauges are connected to the common post, and #1 will activate them, it seems that there is enough power coming through the #1 switch for them to work, but not enough to turn starter. I would pull the switch and check to make sure bolts are tight. Most switches have regular nuts and a lock washer holding cables on. Maybe the vibration from running the boat cause the bolt on #1 post to loosen a little. Double check ground to #1 battery is clean and tight. If still no go, disconnect both batteries from switch and swap them (#1 to #2 and #2 to #1) if the same problem occurs--starts on #2 and both, but not #1, it would seem that the switch is to blame. I'd think if the switch was shot, you'd get nothing from the #1 position, no gauges or nothing, but who knows. Check the wires on the back of switch and see if anything is loose.

 

[Bondo]

Ayuh,... My guess is, ya got corroded connections somewhere in battery #1s start circuit,...

 

[Grandad]

I agree with both ThomW and Bondo. Loose or corroded connection, likely at a large cable termination. I would add that the problem could be at a negative connection, often overlooked, but just as critical in supplying adequate starting current.