Glow plugs not working F20D

[charliewise]

Having been working fine glowplugs are no longer functional -- the light does not appear but I have tested each plug and they appear fine -- do the control boxes fail ? if so are they hard to get can anyone assist in locating one ( east Sussex ) - also ignition switch has been replaced - I am not sure the correct leads have been put back as necessary -- does the glowplug lead coneect to the permanent feed? - or should it be on the 'pressure ' side of stuff ---- currently tyhe glowplugs are 'ON' permanently and the second fuel solenoid lead is on the 'pressure' terminal ( ie the pull in lead) which kind of feels counter intuative! - my circuit diagram helpfully does not show the fuel solenoid (there is an unamed component that may be it !) and the ignition switch dos not indicate what goes where -- maybe you could direct me to a 'proper' electrical diagram !!
Many hanks in anticpation

 

[winston1]

Probably not much help but all I have. This is the electrical for an FX24D. You can sometimes look at these in Japanese and look at an American sold model and maybe more able to identify components. Also posting a page out of the FX24D on the glow plugs. I would suspect you probably have the same components on your FX20D. You can google the numbers and get hits on them.

 

[bmaverick]

Probably not much help but all I have. This is the electrical for an FX24D. You can sometimes look at these in Japanese and look at an American sold model and maybe more able to identify components. Also posting a page out of the FX24D on the glow plugs. I would suspect you probably have the same components on your FX20D. You can google the numbers and get hits on them.

Good call, the F20, F22 and F24 are all in the same family.

 

[bmaverick]

Having been working fine glowplugs are no longer functional -- the light does not appear but I have tested each plug and they appear fine -- do the control boxes fail ? if so are they hard to get can anyone assist in locating one ( east Sussex ) - also ignition switch has been replaced - I am not sure the correct leads have been put back as necessary -- does the glowplug lead coneect to the permanent feed? - or should it be on the 'pressure ' side of stuff ---- currently tyhe glowplugs are 'ON' permanently and the second fuel solenoid lead is on the 'pressure' terminal ( ie the pull in lead) which kind of feels counter intuative! - my circuit diagram helpfully does not show the fuel solenoid (there is an unamed component that may be it !) and the ignition switch dos not indicate what goes where -- maybe you could direct me to a 'proper' electrical diagram !!
Many hanks in anticpation

The F20 has the 3TNB80 engine.

I only have the 3TNC80 manuals, it's the closest to your engine. Glean from these. Compliments of the,

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[charliewise]

Probably not much help but all I have. This is the electrical for an FX24D. You can sometimes look at these in Japanese and look at an American sold model and maybe more able to identify components. Also posting a page out of the FX24D on the glow plugs. I would suspect you probably have the same components on your FX20D. You can google the numbers and get hits on them.

Winston - thank you for this its really hard to source parts in UK - you clearly are are a mastermind of the Yanmar - are you able to answer any of the questions in my original post re the ignition switch - I dont believe it is the original however how would you expect the switch to work -- Ie
battery positive permanent
1st position is always on (in my case ) -- this was connected to a) the fuel stop solenoid (hold open) AND glowplugs
2nd position (pressure point) fuel cut off solenoid pull in assist wire
2nd position - clutch depressed - starter engages

my fear is the glowplugs have been permanently live and may have burned out the control box ( glowplugs themselves work fine when bench tested)

 

[winston1]

The switch on the F series is different than the switch on the YM series and I am unfamiliar with how yours works. Are you able to find the components on your tractor that show on the attachment I sent? If so, some testing with a voltmeter may be in order. Does your switch have a turn to the left? That is the position the YM series switch is turned in order to activate the thermostart system. There has to be a certain position for the key to be in for just activating the glow plugs and nothing else. If not, one of those boxes shown on the attachment would have to be a sensor of some kind for automatic turn on, turn off. You can probably tell I am assuming all this a likely none of what I am saying is correct. Just something for thought.

Stumbled across this since posting. You will notice there is a certain terminal on the switch going to the control module. A multimeter and testing should help you find the culprit. F20 D

 

[charliewise]

Thanks for replying -- no I have no left turn -- it may be given a decent wiring diagram I can jimmy something up !! - lots of probing with multimeter has gone on !!
I dont get why there are 2 wires to the glow plugs --- one seems to be to the control box (yet to be discovered!) and one direct to the plugs - but on mine they are joined together before fitting to an ignition terminal

 

[winston1]

Added to my last post.

 

[charliewise]

Thank you - I have this diagram -- what is unclear is in what position on the ignition switch each post is activated, it is clear the glowplug leads join up -- but should one be energised (eg held) prior to Both being energised --- or may they simply be joined together on the a permanent supply , or on the start post only - DOH
thank you so much for your time and consideration

 

[winston1]

Multimeter testing of switch should let you know what is happening. I believe there should be a switch position that energizes glow plugs only. I do not believe there should be a permanent voltage going to the glow plugs, however, as I stated earlier, this is pure speculation on my part. Glow plugs should not be activated on start post only although they could be activated while starting.