Starting Problem - Instument Panel keeps losing power

[Motters79]

Hello boating peeps!

 

We're having intermittent problems starting my partners boat. Sometimes its fine and starts no problem, other times the instrument panel is dead and nothing happens. No ignition light, no solenoid click, no crank. Starter battery is reletivly new and when the panel light up then it cranks quickly  and starts easily. The boat is 30 odd years old and so is all the electrics inc instrument panel. Can anyone help shed light on this problem? Is there a component in the panel that is more likely to be the culprit? 

 

Sometimes while heating the glowplugs the panel will die before engaging the starter motor, in whgich case we have to just leave it and wait till later and try again. Ive checked all connections to the key barrel and instrument and they all seem solid. tries wiggling everything when panel is dead to see if it flickers into life but no, it either works fine or not at all seemingly at random. 

 

Any helpful advise would be much appreciated.

 

Thanks

 

Edited June 23, 2023 by Motters79

[Jen-in-Wellies]

What engine/control panel make/model? A common culprit is a multi-pin plug and socket between engine and control panel. Search for one of these and if there is one, pull it apart, clean all the contacts, look for loose/corroded wires/contacts and reconnect.

[Motters79]

Thanks Jen. I've just added some pictures.

[Tony Brooks]

1 minute ago, Motters79 said:

Thanks Jen. I've just added some pictures.

 

That does not help with the make and model of the engine. At 30 years old it might be a BMC 1.5, but Thorneycrot marinised others.

 

Do you have solar charging? If so and IF it can charge the engine battery, I got that sort of symptoms with a failing start battery, but this won't apply if there is no solar.

 

Also, worth checking are the isolator switch and the battery posts for corrosion and dirt.

 

If the isolator has a red plastic removable key screw up a small ball of paper and put it under the key. That forces the contact to make a better contact, OR bridge the two terminals on the back while trying to start.

 

take both battery terminals off, negative first, and scrape/abrade the post and inside of the clamps to bright metal. Dress the surfaces with Vaseline. Replace (negative last) and tighten.

[Motters79]

The engine is a T80, Mitsubishi I think. Starter battery is only a year old and is charged by solar via a split relay. Battery connections are all good and tight.

[Tony Brooks]

6 hours ago, Motters79 said:

The engine is a T80, Mitsubishi I think. Starter battery is only a year old and is charged by solar via a split relay. Battery connections are all good and tight.

 

Apart from my battery being 12+ years old, your setup and symptoms are very similar to mine.

 

Apart from the other things said above, put a voltmeter across the battery lead post to lead post (not clamp to clamp), note the voltage. Try to start and note the voltage again. The first should be over 12V, say 12.5 or more. The second can drop to around 10V while cranking. If the voltage does not drop that suggests dirty battery terminals, master switch, multi-plug.

 

If the voltage drops well below about 10V suspect a battery fault. Possibly a faulty cell interlink or a faulty lead burn terminal post to cell connection post.

[Motters79]

Thanks Tony. I'll look at that. Could be the isolater switch as that is very old. It's a bit baffling as the battery is new and in good nick, battery connections are good and when it does start it cranks fast and strong. When it doesn't the instrument panel is dead and literally nowt happens. 

[Tony Brooks]

44 minutes ago, Motters79 said:

Thanks Tony. I'll look at that. Could be the isolater switch as that is very old. It's a bit baffling as the battery is new and in good nick, battery connections are good and when it does start it cranks fast and strong. When it doesn't the instrument panel is dead and literally nowt happens. 

 

When you put the glow plugs on, they will initially draw maybe 100 amps and dropping to perhaps 50. If something has burned or loose contacts, that can be enough to produce an ark that makes things worse. So the master switch is a candidate, but so could the ignition switch a poor crimp on a terminal and battery connections as well as the multi-plug.

 

This could be a problem in the negative part of the circuits

 

The idea of measuring the voltage on the lead posts of the battery static and when cranking is to rule out the battery, and if repeated on the clamps it will rule dirty terminals in or out.

 

Once you have done that, try doing a similar test on both sides of the master switch, each terminal to negative. The results should be similar to what I quoted for the battery test on both terminals.

 

Then pull the multi-plug apart and put back together a few times, if that is the problem this usually effects a temporary cure.

 

I doubt you have a fuse in the supply to the ignition switch (thick brown cable), but if you have that being loose or dirty could cause the symptoms.

 

After that lot it is a question of using the voltmeter to find out where any voltage disappears.