4.3l Mercruiser will not Start

MyWay

New Member
Aug 3, 2022
7
Boat Info
280 Sundancer 2006
Engines
Dual 4.3l Mercruiser w/Alpha I Gen II Drives
MyWay - 2006 Sea Ray 280 with dual 4.3l Mercruiser
  1. Hit Port ignition switch - sounds like a dead battery (clicking sound)
  2. Test Battery 14.7 volts - will start the starboard engine
  3. Bypassed slave solenoid - start clanks, bypassed the slave solenoid on the starboard engine, the starter cranks
  4. Pulled the start - passed the bench test
  5. Put the starter back in - by passed everything (battery straight to starter, jumper to starter solenoid) starter tries to start the engine.
  6. Replaced Slave Solenoid, still have the issue - ignition switch clicks like a dead battery, bypassed the solenoid and the starter just clanks.
Any words of Wisdom would be greatly appreciated.

Jeff "MyWay"
 
Have you tried turning the motor over by hand? Put a socket on the crank bolt and see if the motor is free to turn.
 
Hi Jeff, Welcome to the group! Gotta go with JHorsby3, first thing is to make sure the engine is turning freely, check all connections for a good connection, then I would consider switching starter and solenoid from other engine. That’s a head-scratcher.:(
 
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Hi Jeff, Welcome to the group! Gotta go with JHorsby3, first thing is to make sure the engine is turning freely, check all connections for a good connection, then Inguess I would consider switching starter and solenoid from other engine. That’s a head-scratcher.:(
He said he already took the starter out and it bench tested good. And replaced the solenoid. The only other thing is the movement of the crank or it's hydro locked.

I would say, if it turns over hard with the socket and breaker bar. Remove spark plugs and listen for a ring broken or dragging. Or some other forceful blockage. But if the starter isn't the issue, I'm guessing hydro locked.
 
Another consideration would be the drive unit is binding it up.
 
@MyWay it sounds like you are describing a seized engine. Pull the plugs and put a socket wrench on the main crank and see if the engine will turn over.
 
I can turn the engine with a wrench on the crank and the engine tries to start when I bypass everything (put a jumper cable directly on the starter and then bridge the power to the start solenoid.


I have to take off the risers and manifolds to take the other starter out - and flip them - might flip the solenoids to make sure the new one is not bad.

The drives aren't engaged when trying to start it.

I appreciate all the comments and help - definitely has me scratching my head.
 
The drives can be in "neutral" but it still is connected. The forward and reverse all happens in the lower portion of the drive. So anything binding in the drive could still be suspect.
 
@MyWay Ok, so you established the engine isn’t seized. For clarification sake what you are saying now is that the starter was removed and when bench tested under load it was ok, and when you take a jumper lead on the solenoid it cranks the engine over.

What I’m finding confusing is that you described the starter solenoid clicking then you said you changed it and it makes a clank. The solenoid is just a big relay switch so it doing it’s thing will sound like a click. However, the starter gear engaging with the flywheel but not turning over would sound like a clank.

Have you tested the ignition switch wires for a proper connection and voltage? It’s unlikely the issue is the starter if it turns the engine over with a jumper lead. Could be corrosion or a loose wire on the ignition switch maybe.
 
@MyWay Ok, so you established the engine isn’t seized.
CORRECT - THE ENGINE IS NOT SEIZED, I CAN TURN IT BY HAND AND WHEN i BY PASS EVERYTHING - THE STARTER ENGAGES AND THE ENGINE TRIES TO START.

For clarification sake what you are saying now is that the starter was removed - THE STARTER PASSED A BENCH TEST

and when bench tested under load it was ok, - THE STARTER WAS TEST UNDER LOAD USING A FIELD TEST - START BACK IN PLACE, BATTERY CONNECTED DIRECTLY TO THE STARTER - JUMPER WIRE FROM STARTER CABLE CONNECTION TO SOLENOID SWITCH CONNECT - STARTER ENGAGED AND THE ENGINE TRIED TO START

and when you take a jumper lead on the solenoid it cranks the engine over. - WHEN THE SOLENOID IS JUMPED THE START JUST CLANKS. - I TEST VOLTS INTO THE SOLENOID - 14.

What I’m finding confusing is that you described the starter solenoid clicking then you said you changed it and it makes a clank. - BEFORE AND AFTER CHANGING THE SOLENOID, FROM THE INGINITION SWITCH "REPEATING CLICKING SOUND - REMINDS ME OF CAR WITH A DEAD BATTERY" - WHEN THE SOLENIOD IS BYPASSED, - "CLANK SOUND THAT DOESNT REPEAT UNLESS I PULL THE JUMPER OFF AND PUT IT BACK ON"


The solenoid is just a big relay switch so it doing it’s thing will sound like a click. However, the starter gear engaging with the flywheel but not turning over would sound like a clank. - THIS SOUNDS RIGHT TO ME, ALMOST LIKE I AM LOSING VOLTS BETWEEN THE SOLENOID ANDTHE STARTER.

Have you tested the ignition switch wires for a proper connection and voltage? It’s unlikely the issue is the starter if it turns the engine over with a jumper lead. Could be corrosion or a loose wire on the ignition switch maybe.
- I AM GOING TO TRY TO BYPASS EVERTHING EXCEPT INSTEAD OF RUNNING A CABLE DIRECTLY FROM THE BATTERY, GOING TO USE THE CABLE ALREADY ATTACHED TO THE STARTER - SEE IF IT TRIES TO START

THERE IS A SECOND WIRE ON THE START THAT CONNECTS WHERE THE BATTERY CABLE GOES, HAS A 90AMP FUSE ON IT, DO YOU KNOW WHAT IT DOES, WHY IT IS THERE?


I WILL ALSO CHECK THE INGNITION SWITCH BUT THE SOLENOID BYPASS ON THE STARBOARD ENGINE (GOOD ENGINE) TRIES TO START THE ENGINE. THE SOLENOID BYPASS ON THE PORT ENGINE (BAD ENGINE) THE STARTER JUST CLANKS.

THANKS FOR THE HELP!!!!
JEFF
 
The drives can be in "neutral" but it still is connected. The forward and reverse all happens in the lower portion of the drive. So anything binding in the drive could still be suspect.
-THANKS JHORNDSBY3, I DID NOT REALIZE, I FIGURED THEY DISENGAGED. DO YOU KNOW HOW I CAN TELL IF THE DRIVE IS ENGAGED?

I DID MAKE SURE THE DRIVES WERE NEUTRAL, TESTED THE STARBOARD ENGINE, TRIED STARTING IT WHEN OUT OF NEUTRAL - NO NOISE AT ALL. GETTING THE RAPID CLICKING SOUND WHEN TRYING TO START THE PORT ENGINE (BAD ENGINE) MAKES ME THINK IT IS NOT THE DRIVE SELECTION MONITOR...


THANKS FOR THE HELP!!!!
JEFF
 
Have you tried turning the motor over by hand? Put a socket on the crank bolt and see if the motor is free to turn.
I DID TURN THE CAM SHAFT WITH A SOCKET WRENCH FROM THE FRONT PULLY, TURNED IT A COUPLE TURNS, AND DID GET THE ENGINE TO TURN OVER WHEN BYPASSING EVERYTHING, GOING STRAIGHT TO THE STARTER

THANKS!!!
JEFF

 
Well if you turn the key and it cranks, clunks or what ever, you know the excite wire is good. Thus the ignition switch should be good.

When you jump it, it try's to start. Could you have a battery that shows 14 volts but doesnt have the amperage to turn it over? Like a bad starter cable? Spitballing here as not sitting there drinking a beer wondering
 
Hi Jeff, Welcome to the group! Gotta go with JHorsby3, first thing is to make sure the engine is turning freely, check all connections for a good connection, then I would consider switching starter and solenoid from other engine. That’s a head-scratcher.:(
Drive is always engaged, N,D, or Reverse.

MAKES SENSE - I WOULD THINK IT IS IN NUETRAL SINCE THE SOLENOID IS CLICKING, WHEN I TAKE THE STARBOARD ENGINGE OUT OF NUETRAL IT WON'T DO ANYTING. IS THERE SOME OTHER WAY I CAN TELL?

MORE TESTING:
STARTER STANDARD SET UP, BATTERY CABLE, ANOTHER COUPLE SMALLER CABLES W/ 90AM FUSE CONNECT TO THE STARTE POSITIVE TERMINAL, YELLOW RED WIRE ON THE STARTER SOLENOID POST.

TEST JUMPER ACROSS THE STARTER. LOUD CLICKING IN THE STARTER.

TAKE THE LITTLE WIRES W/ 90AMP FUSE OFF THE POSITIVE,

TEST JUMPER ACROSS THE STARTER. LOUD CLICKING IN THE STARTER.

TAKE OFF THE YELLOW / RED WIRE OFF THE SOLNOID
TEST- LOUD CLICKING IN THE STARTER.

TAKE OFF THE BATTERY CABLE AND RUN A CABLE STRAIGHT TO THE BATTER
TEST JUMPER - ENGINE TRIES TO START.


SO AT THIS POINT i AM THINK THERE IS A RELAY WHERE ALL THE BATTERIES (1 CRANKING, 2 NON CRANKING) CONNECT AND THEN THE

THANKS FOR THE HELP!!!
 
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You keep saying the starter clanks when you turn over the engine rather than a click. A clank would be the starter gear slamming into the flywheel but not being able to turn over the engine because either the engine is seized or the starter has an issue. A click would be the solenoid energizing but either failing to make a connection for the starter motor or the motor has an issue internally that is causing it to not work.

You said you had the starter bench tested so the starter is fine. You claim the engine isn’t seized because the engine will turn over manually with a wrench. The only thing left is that the wiring from the ignition switch has a short. Perhaps the voltage drop when the starter begins to create a load is causing an interrupt in the ignition circuit.

The wiring for this isn’t complicated. The large black cable from the battery negative side goes to the engine block. The big red one goes from positive to the battery switch and then to the starter. The red wire to the 90 amp fuse is the main power line for 12v+ for the engine and related systems. The solenoid is a relay switch. There is a wire that triggers it to make the high amp connection to get the starter to crank. That wire connects to the ignition switch. The power for the ignition switch comes from the 90 amp fuse connection.

It might be best for you to hire a mechanic before you make it worse and thereby more expensive to fix.
 
The solenoid is new.
The starter bench tested good.
The starter activates when key turned.
Starter works when jumped.

So the exciter wire has been eliminated because it clicks, cranks and what ever noise you want to say it is.

The solenoid is making the bendex engage.

A good wire is jumping the starter and it turns over the engine.

Check the battery for amperage. And check the draw on it when starting or trying to start. At 14v it should drop to around 9v. But your battery might not have the amperage to run the starter.

If that checks out, the only thing left is the cable from the battery to the starter. If it has or had been corroded and strands are broken, the volts will be there but the amperage wont. If everything checks out good, then your stringers are rotten. No, seriously though, that is all there is to the system.
 
You stated a "Rapid Clicking". Absolute sign of low voltage.

Rapid clicking is low voltage, caused by bad battery, battery connection, bum cable or relay. Double check all your grounds. The ground wire (or even the B+) may look new, but be crappy an inch up the wire, under the insulation, and /or inside lug. All connections to be CLEAN and TIGHT. Have seen loose starter bolts cause this, too.

Connect a digital volt meter between the engine block (very good ground connection) and the neg side of battery. Try starting it and see if voltage registers on the meter. If there is a voltage reading it is for sure a bad ground cable / connection. Then test the B+ in same fashion. Battery B+ to the battery cable post on starter. Same results / same cause.

This process is called testing for voltage drop, or in layman's terms, testing for a high resistance condition. It can even be done quick and dirty with a cheap test light. Any resistance in the circuit (like bad connection, bad wire, bad relay) will cause the power to seek the path of least resistance, such as the meter or test light, or at least force some through the test instrument.

If the boat has a separate start circuit relay (mounted somewhere and connected to the wiring harness), then a low voltage there could cause the relay to "chatter" and cause what you are seeing.

So many things that cause this, it is nearly impossible to pinpoint without being there to see / hear / test it myself. Been doing this for almost 60 years and it's not difficult, but can be frustration. Electrical gremlins are evil little critters that hide in plain sight.
 
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Thanks Everyone for the help. There are 3 batteries on the boat, I was under the impression they were used to start the engine(s) as it turns out 1 battery is used to start the starboard Engine and the other 2 are used to start the port engine. I switch the main cable from each battery and the Port engine (bad engine) attempted to start. Took the 2 batteries and had them bench tested - 9volts and could not charge - replaced the 2 of them. Hopefully the boats charging system is not bad. It is in a marina on shore power.
Thanks Again for all the help!!!!!

You guys are the best,
Jeff
 

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