Intermittent Starting Problem

D

Doc

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533
Sometimes my starboard Cummins turns over and sometimes it does not. Just clicks and acts like a dead battery. Sometimes I move the shifter back and forth all the way to exercise the neutral safety switch and sometimes it rolls over and sometimes it does not. If not, I move all 4 battery switches to ALL and sometimes there is joy and sometimes not. If not, I press the parallel switch on the bridge and sometimes it rolls over and sometimes not. Today I did all the above and nothing worked. Then I tried it without any extra measures and it started. Go figure.

Until today one of the above procedures has always worked but I am stumped as to the cause. The 8D AGM battery is only 4 months old. It takes a charge well and unless the boat is not run for a day or two the starter engages as if nothing has ever been wrong.

This happened when I bought the boat in late July and all assumed it was the battery...so it was replaced.

Intermittent problems are hell. I wish things would just break and get it over with.

Any ideas?
 
I'm not a mechanic ( so caveat emptor ), but it sounds suspiciously like a starter issue.
 
It's a connection problem. First gotta check the ground cable to the block...only because it's always ignored. Then all the heavy cables to the starter and solenoid. Those will be caring the high amperage that turns the starter over. Last are the smaller primary cables that go to the starter solenoids. On the other end of these primary cables are the neutral safety switch and the starter/ignition switch on the dash. There also may be a ground buss around the helm.

Checking terminals and connections with an amp meter (or multi-meter) may show continuity using the couple watts produced by the meter but a bad connection can't carry the 30+ amps of a starter or it's connections.
 
FWIW, I had similar issues, and took similar actions...it ended up being the key switch at the dash
 
I agree with Charlie. Intermittent ground break is the most likely source.
 
I agree it could be any number of things I would start with the obvious and use a meter to test if you are not get proper voltage at the starter the you can work your way back to determine why if you are then you need to make sure you are getting the amps needed to crank it over.
 
If then grounds are checked and found to be good, take a look at the brushes in the starter motor. That's not easy on most Cummins marine engines but when the brushes are worn and don't make good contact, the result is just what you described.
 
Mine did the same thing and it was the positive connection got corroded. The main connection at the starter solenoid went bad. This was an easy fix remove spray with contact cleaner and reattach
 
I had a similar problem several years ago, problem was worse restarting when engine was warm, ended up taking the starter to an electrician, problem was a worn spacer that would not allow the engine to engage unless the engine had stopped in the correct position.

Regards Brad
 
My Cummins (6bt5.9M) have 2 start solenoids, 1 remote & 1 on the starter,,,sounds like 1 or both may be hanging up.
 
clicking pretty much rules out the neutral switch. If the battery is good then there is a high resistance somewhere in the circuit. All big cable connections are suspect as is any solenoid and the starter itself. Unless the starter and engine are rusty or old bad cable connections are the first thing to check.
I would remove and clean all connections from the battery onward before digging any deeper.
 
First use jumper cables to jump pos and neg/gnd to the starter, and test with key. This bypasses most of your wiring and connections. Next feed 12v to the starter solinoid (bypasses neutral switch and relays). If it doesn't crank now, remove the starter and bench test.
 
Thanks to everyone for their suggestions. I am trying to get an electrician but we are "in season" here in SW Florida.

I have checked what I can reach but the starter, solenoids and relays are on the outboard side of the engine when only the slim and flexible can go.

The only new information is that this problem happens to a cold engine rather than hot. If I stop for fuel or lunch it cranks right up. If I let it sit for a couple of days it won't crank.
 
I think it's a loose connection when it heats up it expends an makes for a tighter fit. This said I would have to be something the is pass voltage when the motor is running so not likely your starter or solenoid so I have to agree with others sounds like a ground. But this is just a guess from someone who is not a mechanic.
 
Mr. slim and flexible boat electrician will be here at 8:30 Saturday morning.
 
At 90 bucks an hour I should be so lucky.
 
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