Starter?

[rickasbury]

I was able to get my a/c working, was only something plugged up in the discharge line....nice 4th watching fireworks right from the marina.

So, I had my dash ripped off, cut all the wires. Had a guy rewire new gauges and dash. Something was wrong - when you turned the key to first position the normal alarms would go off- but when you turned it to start, it made the most God awful shorting sound- somewhere in the engine compartment and I assume the starter- I think it was kicking out the thermal breaker on the starter- everything was dead on the key....and after a few, I think it reset and if you'd hit the key again , make the noise and then dead again. I think I did this like 3x. He figured out his wiring and it seemed to be fine. We did a trial run and everything seemed to be reading right on the gauges- everything was good. So, I launched and it did it....waited a minute started no issue- to the marina - fixed the a,/c- went to leave this am and the key totally dead-shore power all works, radio works on aux. First turn of the key I could hear something wirring- like the trim tabs- and then dead. Just seems to be engine related power. Did this guy ground out something and now it, or the starter is now failed?
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[Chris1956]

You should see if the starter mounting bolts are loose. They can make all kinds of noise, if loose.

The starter circuit should be pretty simple. Power from ign switch to start terminal to slave solenoid to starter solenoid. Of course, the fuel pump feed should be fed from that circuit as well, but I would not expect much else to be powered by start terminal.

A lot of ign keys do not power anything else but the starter (and fuel pump) circuit, when set to "Start".

 

[rickasbury]

You should see if the starter mounting bolts are loose. They can make all kinds of noise, if loose.

The starter circuit should be pretty simple. Power from ign switch to start terminal to slave solenoid to starter solenoid. Of course, the fuel pump feed should be fed from that circuit as well, but I would not expect much else to be powered by start terminal.

A lot of ign keys do not power anything else but the starter (and fuel pump) circuit, when set to "Start".

Thanks Chris- the noise it made was electrical- I recall from the old school horror movies when the mad scientists hits the button on what ever they are trying to create- a shocking sound. The t90 fuse that is on the starter I'm a little confused as to what it does- protect the starter or the alternator? When this happened, the key on the start position something (I assume this fuse) kicked off all power- no fuel pump start or low oil pressure beep when the key is turned to the on position. Then, it or something resets and it would do it again but now nothing. Pretty new starter and batteries, everything is super clean. First instance was gauges installed wrong and it was doing the same thing. I'm reading on line bad wiring can toast a starter, not all starters seem to have this 90 Amp fuse at the starter.

 

[rickasbury]

I had an issues of bad wiring that I think was tripping a beraker/fuse/relay in the ignition system- it would reset and then kick back off. The wiring condition was fixed and it seemed to be good- then made a frying sound and everything is dead- shore power all works, radio works on the accesory position. Is that "fuse" a thermal type breaker/relay or is there something else In the system?

 

[Scott06]

I had an issues of bad wiring that I think was tripping a beraker/fuse/relay in the ignition system- it would reset and then kick back off. The wiring condition was fixed and it seemed to be good- then made a frying sound and everything is dead- shore power all works, radio works on the accesory position. Is that "fuse" a thermal type breaker/relay or is there something else In the system?

It’s just a fuse so once it pops it’s done and needs to be replaced.

there are no automatically resetting breakers. The 50 amp on the engine will need to be manually reset. If it’s coming off and on intermittently you have a loose or dirty connection

 

[Chris1956]

Starters typically use 150amps or more when starting the engine. They are usually unfused. The ign fuse is for the slave and starter solenoids, plus fuel pump and ignition power for spark.

Alternators are usually unfused as well, because if the fuse were to pop, the diodes in the alternator would be damaged.

If I were you, I would disconnect the dashboard wiring from the ign switch. That should help make the issue easier to find. I would trace the starter wire back to the engine and see how it is wired.

Look for melted wires and rubbed off insulation. Slave Solenoids should click. Starter solenoids on 4.3L 5.0L and 5.7L engines often mechanically push the starter gear into the engine flywheel, and then connect power to the starter motor. I would think that would be a good place to look.

You should be able to jumper the starter solenoid (ign off) and listen for the noise. That can help narrow it down as well.

 

[rickasbury]

It’s just a fuse so once it pops it’s done and needs to be replaced.

there are no automatically resetting breakers. The 50 amp on the engine will need to be manually reset. If it’s coming off and on intermittently you have a loose or dirty connection

Well that's what I thought too...the 50 Amp on top of the motor is not tripping. Before apparent failure, when it shut everything down after a couple mins everything would light back up. Is there a thermal breaker inside the starter? Something was shorting/grounding out after the gauge install and the keys also was going dead.

 

[rickasbury]

You should see if the starter mounting bolts are loose. They can make all kinds of noise, if loose.

The starter circuit should be pretty simple. Power from ign switch to start terminal to slave solenoid to starter solenoid. Of course, the fuel pump feed should be fed from that circuit as well, but I would not expect much else to be powered by start terminal.

A lot of ign keys do not power anything else but the starter (and fuel pump) circuit, when set to "Start".

Chris- I'm familiar with a starter selonoid on top of a starter, what is the slave selonoid going to starter selonoid?

 

[Chris1956]

A lot of MerCruisers have a slave solenoid mounted on the block or manifold. The ign key energizes them, and they in turn energize the starter solenoid.

Check out a wiring diagram for your engine and see if you have one.

Here is a video on replacement of the slave solenoid. Note the red reser button on the circuit breaker near the solenoid.

mercuriser slave solenoid - Search Videos

www.bing.com

 

[rickasbury]

Thanks Chris- I absolutely have that- I will re read the thread now I know I have somewhere else to look. I really belive the problem is not a "failure" per say but from an ignition short that pushed something to failure...

 

[rickasbury]

Ok, so I need a plan. I guess I'm looking for an easy check/suspect part when I really need to start with the basics and work my way through this. @Chris1956 suggested i unhook the dash from the ignition- not sure what that means- i know when the dash was put back together he made up one harness, if not two, and it/they plug in lower in the dash area- disconnect that? I understand the thought- if something is still bad with the gauge wiring then it is isolated. The only hesitation in doing this is after the wiring was corrected i ran the boat. But still makes sense- maybe something is not tight or making a good connection- he did say he had to extend the harness he made as it was to short- so, assume that is where I'm at, harness disconnected- what am I checking next? I've googled trouble shooting ignition issues but don't really come up with much....is there a step by step somewhere I can go by?

 

[racerone]

Make sure you read the fine print on your insurance policy.

 

[Chris1956]

Rick, dashboards are normally powered from both the ign key and a direct connection to the battery. The ign key powers the gauges and the direct connection, everything else. Since you are having trouble with your starting circuit, after your dashboard electrical repair I would recommend you disconnect the dashboard power from the ign key. At this point you should check for the noise and isolate it to a component.

Next is to get a wiring diagram for your engine. MerCruiser wiring diagrams are pretty easy to find, but you will want one close in year to your motor, and ideally the same kind of engine, V or inline, as MerCruisers can have different ign systems on the inline 4 and V6/8 engines.

Now follow the ign power wire on the diagram from the ign switch to the ign module, fuel pump, oil pressure switch and wherever else it goes. Do the same for the start wire from the ign switch.

I will assume you have an electric fuel pump. That will be powered by the ign switch when in the start position. After the engine starts, the oil pressure switch will send a signal to a relay to power the fuel pump when the boat is running.

In addition, the start circuit will power the slave solenoid. When the slave solenoid is energized, power will flow to the starter solenoid. So the wiring diagram should show a direct battery connection to the starter. The circuit breaker should power all else. Normally the power distribution will be the starter solenoid large terminal, where the battery cable connects.. There will be several reds and an orange wire on the starter solenoid connection. You should see all of this on the wiring diagram.

Now it is time to compare the wiring diagram to your wiring harness. It can be daunting, but as you study the diagram and boat, it should become clearer.

Not sure if that helps.

 

[rickasbury]

Yes sir, absolutely does. I replaced the starter a couple of times- I don't recall more than a couple of wires to the starter selonoid- other than the hot.

So I'm pretty familiar with where the bits and pieces are. I did not see the new wiring before the dash went back on- I believe there was a separate feed if not a second harness connection at key- last thing worked on probably the first place to look. Will do that, disconnect the gauges if that is separate from the key.
What would be the symbol on the wiring diagram to show if the starter is ignition hot? I would guess so- let me do a little hunting for the diagram and see what I can understand.

Very appreciative of the guidance

 

[Chris1956]

I was working from memory. I had a 1988 4.3LX V6 MerCruiser, which I sold in 2006, so it has been a while. I replaced the starter and slave solenoid on that motor and seem to remember that the power wires plus the orange alternator wires were all on the positive battery post of the starter solenoid.

Your motor is much newer, and probably has some wiring changes, and likely has that electric fuel pump, whereas I had the mechanical one.

Even a Clymer service manual will have a wiring diagram, if you cannot find one somewhere else.

A 2 min search turned up some service manuals. Maybe you can find better ones. They are likely overkill for what you need anyway.

This link has some MerCruiser service manuals

MerCruiser Service Manual Free Download PDF

More than 30+ service & repair manuals for such sterndrive engines as MerCruiser you can free download .

www.downloadboatmanuals.com

Page 265 of this link has some starter wiring info. Looks to be for an older motor though.

Mercury Mercruiser #24 Service Manual - Marine Engines GM V-8 305 CID (5.0L) _ 350 CID (5.7L) [PDF, ENG, 12.3 MB].pdf

drive.google.com

 

[rickasbury]

Thanks, @Chris1956 - mine is 06, so newer but the starter probably not that different.
I thought I should start with the batteries. I went to harbor freight , bought a hand held battery load tester. Batteries were near dead. One to find was really dead. Charged from Friday evening until this am- starting battery was at 9 volts, needless to say when I hit the load it just read bad. The orher, however , Charged back up and passed the load test
When I switched to battery to batter 2, the ignition was still dead. I reached down and started looking for lose wires- then I heard the whir of trim tabs when I moved one of them- key functions then. Seemed normal. Could not start it as on land. The electric pump fired up and the beep for no oil pressure- normal .

I've attached some pictures, best I could of the wiring hook up to the selonoid- note that yellow wire, which goes from the selonoid to inside the starter the coating looks pretty melted. This is starting to confirm my very uniformed theory that when the wires that were installed wrong at the dash and I heard something grounding out I think it was battery one and the selonoid / starter. I would have loved to see if would have started. I think looking at the pictures all the connections are clean and I must have jiggled that post enough for something to make contact- thoughts?

 

[Chris1956]

I do not think the copper strap that powers the starter looks too bad. It isn't shorting to the case, right?

Shouldn't there be a ground wire on the starter solenoid in pic 1? Maybe you don't need it, I cannot remember, but thought most had one.

Your trim tabs should not move, unless the switch is activated. That sounds like a wire is disconnected. The trim tab switch should be hot at all times.

You should be able to put power (say 10A on the yellow/red wire) and the starter should activate. I think that is first test. use a 12Gauge wire to jumper from the battery to that yellow/red wire on the starter and see what happens. The motor should crank. If not, you have found an issue. If so, move to the slave solenoid wiring.

 

[Bondo]

Shouldn't there be a ground wire on the starter solenoid in pic 1? Maybe you don't need it, I cannot remember, but thought most had one.

Nope,.... The starter is grounded through the block,......

The outer tiny terminal is to provide battery power to an electric fuel pump, or to the points, if a points fired ignition,...

 

[rickasbury]

I have an electric fuel pump- next time I have the boat home I will check the tabs- but I swear when you turn the boat on or off I hear them raise- I also hear the fuel pump.
I will have to save this until next trip home with the boat- so no one seems to think that the bad wiring at the dash- which caused a horrific shorting sound from the engine compartment, has anything to do with my issue? The melted yellow insulation on the wire going into the starter from the selonoid zip? I've yet to find a specific wiring diagram for the starter circuit- none show the fuse on the starter, the T 90. There is a large heavy wire coming over from what would look to be the battery switch that goes to a post on the left side of the starter- no on the selonoid. It looks like another smaller wire should go to the alternator- not sure where the other wire on the t90 fuse goes off to...and jumping the yellow red wire, the one on the right side of the selonoid correct? You say jump with 10 amps- how the heck do I know what amps I'm going to hit it with off the battery, it will be what ever the battery sends it through the jump wire? Or did you mean use 10 gauge wire @Chris1956 ? The bright yellow in all pictures is melted insulation...

 

[Chris1956]

I was guessing the starter solenoid uses 10 amps. A normal wire size for that much current would be 12 ga. I just didn't want you to use too light of a wire and it get hot and burn your fingers.

Sometimes trim tabs do have an automatic raising function when the ign turns off. It is pretty rare though.

You should hear the fuel pump run when you first turn the ign on. It should stop after a few seconds.

Starting circuit diagrams for different MerCruiser models will be pretty close to each other. I would not worry too much about the placement of the fuse, but do use one with the electric fuel pump as it will also have the relay and starter circuit connections. I expect the starter to be direct connected to the battery, and the fuse will feed the rest of the starting circuit and the boat. These can be wired a bit differently but make no difference in troubleshooting.

BTW, starters do short out, and draw massive amounts of current, say 300A. Jumpering it and listening to it crank the motor normally, will eliminate that possibility.