Bunch of electrical questions on 4cyl Mercruiser Sea Ray

[gixxerjim]

This is a bit convoluted to how I got where I am, but if you can help me out with advice I would appreciate it:

I threw a different battery in my new to me '88 Sea Ray 130hp I/O last year after the battery that was in it tested poor. The battery I put in was a trolling motor battery that I had laying around, about 2.5 yrs old at the time (3.5 now). Never gave me any trouble after I put it in, but it is a 405CCA/500 Marine CA/75 battery whereas Sea Ray specified a 500CCA/725Marine CA/95 battery for this boat. One thing to note although my gauge consistently reads 13.5V while engine is running, my fishfinder occasionally, usually after an hour or more of use, will throw a "LOW VOLTAGE WARNING" message across the screen....

SO:
On the second to last day of our vacation week at a cottage where we ran the boat every day, I added a 12V power supply outlet to my dash to power a Sevylor inflator for pumping up innertubes/charge my phone for emergencies use if needed etc (no I am not big cell phone user!). When I hooked it up I wired it to the back of the engine bay to the breaker directly above and to the starboard side of the motor. This breaker is blue with a big red reset button on it and a + and - terminal under it. These terminals are the source of 12VDC for my cigarette lighter style power supply. I chose this spot rather than the battery because the wires I bought were about 4' short of reaching the battery, in all honesty this was a shortcut on my part. Everything worked fine so we were having a good old time for a day and a half no changes.

Late the next day the boat wouldn't start. Turn the key, single click, nothing. Spent a minute farting around with the little-bit-finnicky shifter to assure it was in neutral, etc and then it started. Figured the shifter was not reading neutral consistently and kept boating. The next time I started it it wouldn't start at all until I rapped on the starter with a wrench. So I am thinking the starter is shot.

Returning home I decided I should really get a new battery of the proper size and rating in the boat, bought a 875CCA/1000 Marine Starting motor, charged it for 90min, installed and ran the boat a few hours of tubing with the kids, only using the inflator when the boat engine was running. Toward the end of the day the "LOW VOLTAGE WARNING" came back on despite the 13.5V on the boat gauge, then awhile later the boat wouldn't start. Immediately rapped on the starter and still nothing. Then it started when I rapped on the starter while my wife turned the key.

So, if you are still with me thanks! I have three questions:
1) is my 12V power supply in a bad spot that is somehow weakening the supply to the starter or draining the battery?
2) is my next step plan of testing the starter right? It seems clear the starter is dying but what do you all think?
3) could it be the alternator? Perhaps the battery is weakening due to no alternator or weak alternator and the only way it can supply enough juice to overcome the startup friction in the starter is if the starter is jolted to assist. This makes sense given the low voltage warning on the fishfinder.

Or am I missing something else altogether?

 

[Silvertip]

Re: Bunch of electrical questions on 4cyl Mercruiser Sea Ray

You first need to determine which instrument is providing the proper reading. If the dash voltmeter is reading 13.5 volts the battery is charging and the alternator must be ok for that to happen. You locator "low voltage" settings are adjustable so it may be it is set to trigger at too high a voltage. The solution is to buy or borrow a good hand held multitester or voltmeter and actually measure the voltage with the engine running. Then and only then are you sure which instrument is accurate. The next step is disconnect and clean (make them shine) the battery cable terminals (both ends) and then make sure they are tight when installed. Also inspect the entire length of each cable for lumps or bumps under the insulation that would indicate corrosion going on. The main culprit here is where the cable goes into the terminal. It is common to have corrosion in that area. If present, either replace the entire cable or cut the end off and attach new ends. If that still presents a starting issue, you may have a starter or solenoid problem. The starter can be check and rebuilt if necessary by any automotive starter/alternator shop (also called Auto Electric Shop) in the area. Be sure you "troubleshoot logically" and not simply throw parts at this issue. Thats an expensive way to correct a problem.

 

[gixxerjim]

Re: Bunch of electrical questions on 4cyl Mercruiser Sea Ray

Thanks, I will check all my connections.

Was my choice of 12V supply okay on the outlet I wired?

 

[Silvertip]

Re: Bunch of electrical questions on 4cyl Mercruiser Sea Ray

It doesn't matter where you get +12 volts and ground from. +12 volts is +12 volts. You can get it at the battery, at the starter solenoid, anywhere under the console at the fuse panel. Ground is ground wherever you find it. Again at the ground buss on the fuse panel, the engine block, the negative terminal of the battery. Unless something is plugged into the receptacle you added, it cannot draw current. It's a passive device so it just sits there. If you run that inflator thing or any other high current draw device like a large spot light for long periods, yes, you will draw down the battery.

 

[gixxerjim]

Re: Bunch of electrical questions on 4cyl Mercruiser Sea Ray

My father in law and I tested the battery, starter, solenoid and alternator in the boat the other day. Everything tests out OK. Correct voltage from the alternator, correct current draw down from the starter, correct capacity on the battery etc.

The only thing I can think of is the starter doesn't show it's issues until it gets hot sitting next to the engine all day.

Anybody ever have any experience like this?

 

[Silvertip]

Re: Bunch of electrical questions on 4cyl Mercruiser Sea Ray

How did you measure current draw from the starter. The starter needs an ammeter inserted in series with the cable to determine that. What you need to do is measure the voltage at the starter solenoid while actually cranking the engine. But even that's not the same actually measuring current draw.

 

[Fl_Richard]

Re: Bunch of electrical questions on 4cyl Mercruiser Sea Ray

If the starter has a built in selonoid then it's possible as it heats up the selenoid starts to stick.

I had a TransAm that this happened to. It would get hot and not start a quick rap on the starter worked everytime. My wife drove the car at the time, guys would see he in the parking lot with the hood up. She'd climb out with a hammer give it a wack and drive away. The looks she used to get....

 

[Silvertip]

Re: Bunch of electrical questions on 4cyl Mercruiser Sea Ray

That's because the heat shield was never installed after the starter was originally worked on. You might even try that on this engine. An aluminum sheet bent to deflect exhaust manifold and block heat from the starter may prevent that (it's called hot soaking). But to separate the electrical system (apparent dead battery) from an engine issue (starter doesn't work) do the test I just described. When the engine doesn't want to start, place a voltmeter on the battery and crank the engine. If the starter fails to crank the engine but voltage remains in the 10.5 - 11.5 volt range, you have a starter issue not a battery issue. If the battery is the issue, then voltage will drop below 10.5 volts when you try to crank the engine. The starter is the highest current draw on the boat.

 

[gixxerjim]

Re: Bunch of electrical questions on 4cyl Mercruiser Sea Ray

How did you measure current draw from the starter. The starter needs an ammeter inserted in series with the cable to determine that. What you need to do is measure the voltage at the starter solenoid while actually cranking the engine. But even that's not the same actually measuring current draw.

My father in law has an Sun meter with instructions for testing all aspects of the starting system, which we went through from start to finish. No problem areas came up, but then again my issue only occurs after a couple hours of running....

I will have to install a heat shield to the starter and see if this problem goes away next year.

 

[SteveOH]

Re: Bunch of electrical questions on 4cyl Mercruiser Sea Ray

Hey Jim, not related to your starter problem but you should connect the lighter socket to the under dash fuse panel rather than the breaker. See if there is an available fused output on the panel and this would be your best bet in terms of safety. If you keep it connected to the breaker make sure its on the load or output side of the breaker (not the side going to the battery or 12V source) and add a fuse holder within inches of the breaker output connection (to the socket) with a fuse around 20 amps. This will provide ample power for the socket and protect the wire from burning should it short. As for testing the starter - follow silvertip's advice - put a multimeter across the battery during the no start and watch the voltage.
Hope this helps
Steve