A rather strange engine problem

[SailorJoJo]

So this is the thing. I have a nanni diesel engine in my boat that acts rather strange. The engine starts instantly when it actually starts. But sometimes it’s just dead silence when I turn the key.

To add context to this. The issue as far as I can remember has never happened at dock or after a night at anchorage. It happens after I sail for a while and then try to start the engine. I’ll glow the engine for around 7-10 seconds, and it’s just silence when I turn the key.
But here’s the thing. If I just wait around 15-30 minutes it will start up again as if there never was a problem. And this have become a pattern at this point..

I changed the starter battery bescause I tested it and it was bad. But today the same thing happened. The weird thing is how systematic the problem is. Every single time it won’t start, it will start again after a while with no problems.
In a way I almost wish that it just wouldn’t start so I could figure out what the problem is.

Anyone experienced something similar or have any inputs to what the issue might be?
The only conclusion I have now is that it’s the starter acting up. I’ve checked the voltage on the batteries and there’s no issue there.

[JoeRobertJr]

I'd start by checking (and cleaning) the starter solenoid connections. If the problem persists, then check for voltage at the starter solenoid control wire when you turn the key.

[Cheechako]

In addition to the cables going to the starter and the ground cable needing to be clean at the engine connection, look to see if there are any plastic multi pin connectors from the 'dashboard' to the engine in the wiring loom. I had this problem with a non Nanni engine. It sometimes would not react to the key switch at all. On the back of the engine was a 9 pin connector in the wire loom. Opened it up and it was fairly clean but did have some light corrosion on the pins. Cleaned them up and sealed the connector and it never failed again. This type of connector would likely be near the engine or near the dash module.

I assume when you say "it would not start" it makes no reaction at all? No solenoid clik etc? "But sometimes it’s just dead silence when I turn the key."

[phorvati]

Originally Posted by Cheechako

In addition to the cables going to the starter and the ground cable needing to be clean at the engine connection, look to see if there are any plastic multi pin connectors from the 'dashboard' to the engine in the wiring loom. I had this problem with a non Nanni engine. It sometimes would not react to the key switch at all. On the back of the engine was a 9 pin connector in the wire loom. Opened it up and it was fairly clean but did have some light corrosion on the pins. Cleaned them up and sealed the connector and it never failed again. This type of connector would likely be near the engine or near the dash module.

I assume when you say "it would not start" it makes no reaction at all? No solenoid clik etc? "But sometimes it’s just dead silence when I turn the key."

My friend has a nanni, that wire harness is nightmare. You need to clean terminals and inspect crimps. Thise are copper wires likely not tinned. So they get rusty and develop resistance. Your symproms point to that

[capt jgw]

I'm not familiar with Nanni engines but I am with Universals which are also Kubota based engines. If there are "trailer plugs" in the wiring harness, they're only there to make it easier for the boat builder to install the engine. You don't need them. Just cut them out, trim back to clean wire and reconnect each wire with heat shrink crimp connectors. You can cut out any excess length while you're at it too, you don't need that either. Your starting problem is most likely a wiring issue. On the Universals those plugs have caused many fires. Also check your wiring connections on the engine and control panel, any loose or corroded connections can cause the problem. Be sure to check the big battery positive and negative cables too, the ground cable connection on the engine is a common trouble point. It can vibrate loose over time and accumulate grease and crud. They tend to bolt it to the block at the closest and most convenient point to the battery but the best spot is one of the bolts holding the starter to the engine. Put the voltage where it's actually being used.

[workmaster2n]

I just had a similar problem present itself. Eventually I found the relay between the In Gear Start Preventer and the starter had gone bad. The In Gear Start Preventer is the microswitch on the throttle that prevents the engine from starting when the throttle is in gear (there is probably a better name for it).

In hindsight, what I wish I had done for diagnostics:

Get into a situation where you think the engine will not start (I think this means go sailing for a bit in your case). Use the glow plugs to warm up the diesel. Leave the key in the ON position (so the fuel pumps are on). Now go jump the solenoid/starter. You do this by taking a wire (or screwdriver) and connect the lead on the solenoid where the ignition switch comes in and connect it to the lead that connects to the starter.

What we are doing is checking the battery, battery connections, and starter. If the engine starts, we know these things all work. If these things all work, it means the problem is the solenoid, the wiring up to the ignition switch, or the ignition switch itself.

Let's pretend the engine starts by jumping the solenoid to the starter. Now work your way backwards towards the ignition. If there is a relay between the solenoid and the ignition switch, test that that is still functional. Also test that you are getting proper voltage to the input of the solenoid when the ignition is in the start position. If all this checks out, go up the loom towards the engine console.

Check if there is a relay between the In Gear Start Protection switch and the solenoid. Check the microswitch on the In Gear Start Protection.

If you get all the way here, I think the only thing left is the ignition switch.

Now, of course, intermittent start issues are always a bugger to debug.

Good luck and let me know if there's a step that doesn't make sense.

[Tin Tin]

Does this engine have an electric fuel pump?

[boatpoker]

Last time I had that issue it was a mildly corroded ignition switch but the other electrical advice here is sound.

[Khaos13]

WORKMASTER2N has it right. Neutral safety switch. Something is interrupting the start circuit.

[Cheechako]

Originally Posted by Khaos13

WORKMASTER2N has it right. Neutral safety switch. Something is interrupting the start circuit.

Yes, definitely had that issue once also. I'm not sure all sailboats have a NSS though. But if the OP's boat has the Sea Star, Teleflex style controls it probably does.

[BobFord]

I mention my experience ,should it help. No start action , checked wiring and connections ,starter motor , replaced battery, replaced start solenoid - no success. Finally discovered that the key ignition was faulty. Spray of contact cleaner in to key hole - alls well !! BTSOOM !!

[SailorJoJo]

This forum is incredible! So many great tips and advice. I’ll start checking connections and take it from there. It’s such a difficult thing though because I have such a small window from when it doesn’t work to when it starts working.

The contact cleaner in the key hole is actually very interesting because it tends to almost stuck a little bit when it’s turned.
I truly appreciate everyone taking the time to give advice!

[Nicholson58]

Originally Posted by JoeRobertJr

I'd start by checking (and cleaning) the starter solenoid connections. If the problem persists, then check for voltage at the starter solenoid control wire when you turn the key.

Great advice! Crappy crimps and old wire is the #1 root cause on our boat. I keep heavy jumpers to bypass whole wire system’s to find the bad bits.

Starter solenoids that I have serviced all have a thick round washer on the solenoid. Activation causes the starter pinion to engage the engine flywheel ring gear AND at the end of stroke the washer slams into two copper lugs thus completing the circuit to the start motor. The washer is copper and erodes over time due to arcing. Eventually the washer gets unreliable and eventually fails.

On my starter it’s possible to rebuild with a new washer. I also keep a new complete solenoid on board.

Also look at the two big copper contacts. These can be cleaned, rebuilt and sometimes rotated in their mounting hole to give new surfaces. Note the big copper bolt with the square pattern under the head. The head is one of the contacts. It can be turned by 90 degree steps. In a pinch I have built up a contact by heavy application of silver solder or soldering on a copper chunk. This will get you home.

Pictures: burned out after four seasons, new one. You used to be able to buy just the washer subassembly but mine is no longer offered.

[Nicholson58]

Originally Posted by SailorJoJo

This forum is incredible! So many great tips and advice. I’ll start checking connections and take it from there. It’s such a difficult thing though because I have such a small window from when it doesn’t work to when it starts working.

The contact cleaner in the key hole is actually very interesting because it tends to almost stuck a little bit when it’s turned.
I truly appreciate everyone taking the time to give advice!

More great advice. My starter switch failed twice in 12 years. I finally did a search for a much higher amp rated switch. Everything powered by the switch, accessories, gauges, work better now.

[GrowleyMonster]

If you just short the solenoid, does it start right up? Or at least turn over?

A bad starter motor won't roll the engine over at all. It won't cause an intermittent problem. Your problem is either the solenoid or elsewhere in the start circuit.

I think.

Checked your transmission control? It should turn over even in gear, unless an idiot switch is preventing it starting in gear. But maybe not.