Starting problems

[Detling]

Hi,

 

My boat has an nice Isuzu 42 nice big diesel which runs fine, I now have a new problem when starting. When I turn the key to the 'preheat' position (yellow glow plug light on) it now takes forever (about 80 seconds) before I can turn the key to start the engine. The engine starts fine only cranks for 1-2 seconds and fires and picks up as a good engine should. Even if I stop the engine after running along the canal for 2 hours (engine well warm, battery showing 13 volts) the time required before I can turn the 'ignition key' to start is still well over a minute. I would expect a few seconds with a warm engine. So I have two questions really

1, what controls the key ie unlocks it so that I can turn to the start position?

2, any ideas as to why? AFAIK the battery volts are good and engine turns well on starter motor when I can get there, The engine is 4 years old has only done 300 hours though. It used to take about 10-15 seconds when cold not the age it does now.

[Ex- Member]

Hi,

 

My boat has an nice Isuzu 42 nice big diesel which runs fine, I now have a new problem when starting. When I turn the key to the 'preheat' position (yellow glow plug light on) it now takes forever (about 80 seconds) before I can turn the key to start the engine. The engine starts fine only cranks for 1-2 seconds and fires and picks up as a good engine should. Even if I stop the engine after running along the canal for 2 hours (engine well warm, battery showing 13 volts) the time required before I can turn the 'ignition key' to start is still well over a minute. I would expect a few seconds with a warm engine. So I have two questions really

1, what controls the key ie unlocks it so that I can turn to the start position?

2, any ideas as to why? AFAIK the battery volts are good and engine turns well on starter motor when I can get there, The engine is 4 years old has only done 300 hours though. It used to take about 10-15 seconds when cold not the age it does now.

 

Sounds like the glow plug is naff. Unless it's really cold I never bother pre heating. We have a 2.5 litre diesel it's always started on compression alone.

 

I would ignore the light and just fire it up.

 

Just re read Q1 in Blue. So you can't turn the engine over until the light goes out and releases the key. Didn't realise that oreven know some engine ignitions did this.

[RobinJ]

1, what controls the key ie unlocks it so that I can turn to the start position?

Many systems just use a timer, so after 'n' seconds, arelay is released.

It is possible that some systems use temperature control feedback, but not seen one?

 

I would check to see if all the heaters are working (simplest way is to energise them and put your finger on each one to see if they get hot) (or you can test them electrically)?

Satisfied that they are ok, I would look at the wiring diagram for the engine and see how the heaters operate the starter interlock mechanism!

 

It is possible that a simple RC circuit is used to control the relay and one of the components has gone wherever!

[Chris Pink]

 

Just re read Q1 in Blue. So you can't turn the engine over until the light goes out and releases the key. Didn't realise that oreven know some engine ignitions did this.

 

Seems like the nanny state gone a step too far to me.

[jonathanA]

Have you been told to wait for the yellow light to out before moving to the start position OR does the key not move until the yellow light goes out ? i.e there is some sort of interlock on the ignition/start key switch ? (which seems very unusual /complex)

 

on a warm engine there should be no need for preheat and you should just go straight to start..

 

Edited for spelling

Edited March 4, 2013 by jonathanA

[Pretty Funked Up]

how very strange.

 

If the key wont physically turn to the starter position then I'd be thinking along the lines of a worn and failing ignition barrel. Try wiggling the key a bit when tryign to move to the starter position.

 

If the key goes to the starter postion but nothing happens you have a dodgy connection somewhere.

[IanM]

What they said.

 

You should be able to just turn the key to start without the 'heat' bit and therefore just hold it at 'heat' for the length of time you want before starting.

[Detling]

Thanks for the ideas, mainly seem to agree with my thoughts, but I can't seem to move the key till light goes out. A friend has suggested that whatever is the sticky bit will be in the control box and therefore not warmed by the engine but maybe by current flowing to yellow bulb. I am off to the boat tomorrow so will have the top off and play. It was brass monkey weather when the problem occurred.

[Sir Nibble]

Don't know this system but it sounds as if a temperature sensor on the engine has become disconnected or failed, probably the former. The result of this is that the glow plug timer believes the engine to be at sub zero temperature the whole time. Interlocked ignition switches are not unusual but do appear, usually to prevent ignition being turned off until engine has stopped. Inhibiting the key from turning until the glow period determined by the temperature has expired is in line with the modern "idiot proofing" of design which of course all falls down if the idiot is the designer!

[Detling]

Got back to boat, today it took 12 seconds before key turned to start engine. It was about 7 degrees today about -3 when problems occured. This suggests that the interlock thing is in the key switch. Not worried by 12 seconds.

[Pretty Funked Up]

Agreed but this bit...

 

Even if I stop the engine after running along the canal for 2 hours (engine well warm, battery showing 13 volts) the time required before I can turn the 'ignition key' to start is still well over a minute.

 

Suggests its not temperature based. Sounds odd to me but then i have funny ears

 

any chance of a picture of the starter panel?

Edited March 8, 2013 by Pretty Funked Up