Diesel Ignition Circuit

[OGITD]

Hi All,

Some electrical help needed on a Bukh DV10ME.

The starting was not always immediate, the ignition light / circuit was 99.9%, but when no light was apparent and resultant loss of circuit I just checked, cleaned & tightened the small spade connection on the starter and everything was fine.

On a scale becoming more frequent than acceptable, the starter would fail to turn over and all you would hear was the solenoid distinctive click. But after two or three attempts with the ignition it burst into life.

So I removed the starter and had it fully reconditioned (looks like new), replaced the starter now I definitely do not have an ignition circuit. All the wires are in such a configuration that it should? be impossible to connect them up incorrectly, but there is always that chance.

Really appreciate help with this issue, not an electrical chap, can check, clean, crimp tighten, check for voltage as long as I now where + & - are, solder and heat shrink but I just don’t know electrics.

My initial thought is to sand / clean all the metal to metal faces between the starter and the engine block to ensure I have a good earth as the unit has been painted.

Thanks once again,

OGITD's /forums/images/graemlins/confused.gif

 

[savageseadog]

Use a 12v bulb and wired to crocodile clips for testing. Connect one side to battery negative, on the battery itself and other side to the starter positive connection, that should light up permanently. now connect to the small terminal, that should light up when you press the starter button. Then connect the clip that was on the battery negative to the engine block and repeat, you should obtain the same result.

 

[oldharry]

"the unit has been painted."

Thats the most likely problem. The original fault sounds more like a poor contact in the heavy current circuit - enough current to work the solenoid, but no the starter itself.

Check all the connections - particularly where they have helpfully painted the starter! Take particular care with the negative return circuit from the engine to the battery itself - this is a very common source of trouble.

IF there is still no joy, get a small digital multimeter for a few quid from the local car accessory shop or wherever, switch everything on, and connect the meter between the battery plus, and each connection - not always easy where they are insulated. If you get a reading much above half a volt (it doesnt matter with a DVM which way round you connect it) then that joint is suspect. Do the same between the starter casing (no paint!) and the battery minus, then the engine block and batt minus. Everything has to be switched on of course, including the starter via the ignition key. You will almost invariably get a small reading across any connection - what you are actually measuring is the voltage drop across the connections. More than a volt or so and it is enough to affect the operation of the high current starter.

Good luck - these niggly little faults can be quite difficult to track down!

 

[Bloater]

It just seems strange calling it an 'ignition' circuit, but the 'starter' circuit is the same for both petrol and diesel engines...

Do you still get the 'click' that you had before? this of course is the starter solenoid.

You can check for a voltage on all the terminals. You should have a perminant 12v on the large thick cable connected to the starter motor. You should have 12v on the smaller 'ignition' connection but only when the key is turned and you get that click.

You need to check that you have continuity between the starter motor body and the neg terminal on the battery.

You must clean all the paint off the starter motor where it connects to the engine block otherwise no electrical connection.

If all the above are working and present then you have a faulty motor.

Hope this helps.

 

[Phoenix of Hamble]

You also need to check the wiring from the battery to the starter, both +ve and -ve sides very carefully.....

A weak connection and/or damaged cable can stop enough current flowing, and also cause the symptoms you describe.....

 

[John100156]

Just a couple of comments add to whats gone before to throw into the pot:

1. The condition of your batteries? Could it be when trying to start its dragging the battery voltage too low. Try testing the voltage on the output side of the solenoid when starting. Take care when doing so.

2. Did they change the contacts in the solenoid, they should have!

 

[philip_stevens]

Take your battery terminals off and clean the posts and inside of the clamps. Refit the clamps tightly, and try again.

If the solenoid it closing and the starter is not turning, it could be a bad contact on the battery terminals.

 

[OGITD]

Thanks Guys,
I have a couple of cheap multimeter's in the tool bag.
Last month I was learning all about 80's vintage Yamaha 2~
carburetion....so this month its ignition systems, but always good to know when away from port & when others require help.
Will keep you posted & thanks once again.
OGITD's

 

[savageseadog]

Suggest you use the lamp as I suggested. Meters can give misleading results unless you know what you're doing. Be careful when you're messing about, the starter or engine just might decide to go.

 

[OGITD]

Re: Diesel Ignition Circuit THANKS!

Thanks to all for the help identifying the problem.
Everything now works first time every time.
Plus corrected a number of loose connections along the way.
/forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[philip_stevens]

Re: Diesel Ignition Circuit THANKS!

So what or where was the main fault? Interested to find out.