# Fuel stop solenoid WOODWARD



## telsa (May 22, 2015)

It's idiot easy to check out the circuit.

1) Identify '30' and '87' -- these will be marked on the under belly of the relay, which you must remove.

2) Noting the corresponding female connections, jack in a DC ammeter.

Don't turn anything on... don't attempt to start the motor.

Just right there you've got the amount of amps flowing into the solenoid -- which will pull up the second you jack a DC ammeter across 30 & 87.

3) Remove your ammeter and restore the relay. :thumbsup:


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## JBoen (Jun 27, 2016)

telsa said:


> It's idiot easy to check out the circuit.
> 
> 1) Identify '30' and '87' -- these will be marked on the under belly of the relay, which you must remove.
> 
> ...


But the thing is solenoid gets hot when it holds, is that normal? Just as hot as your smartphone while playing some games. 

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## inetdog (Apr 13, 2016)

JBoen said:


> But the thing is solenoid gets hot when it holds, is that normal? Just as hot as your smartphone while playing some games.
> 
> Sent from my MI 5 using Tapatalk


Yes, that is normal. The DC coil has to use resistance to limit the current and that generates heat.


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## splatz (May 23, 2015)

inetdog said:


> Yes, that is normal. The DC coil has to use resistance to limit the current and that generates heat.


Wouldn't a solenoid be a primarily inductive load?


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## inetdog (Apr 13, 2016)

splatz said:


> Wouldn't a solenoid be a primarily inductive load?


And a pure inductor offers no impedance to DC.
An AC solenoid can use inductance to limit current.

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## JBoen (Jun 27, 2016)

inetdog said:


> And a pure inductor offers no impedance to DC.
> An AC solenoid can use inductance to limit current.
> 
> Sent from my XT1585 using Tapatalk


Do you think its bad if i change the relay with OMRON timer H3CR (0.2s)? 

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## JBoen (Jun 27, 2016)

JBoen said:


> Do you think its bad if i change the relay with OMRON timer H3CR (0.2s)?
> 
> Sent from my MI 5 using Tapatalk












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## TRurak (Apr 10, 2016)

Solenoids generally run hot. Especially if they are energized for extended periods.


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## JBoen (Jun 27, 2016)

TRurak said:


> Solenoids generally run hot. Especially if they are energized for extended periods.


Thank you

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## telsa (May 22, 2015)

The DC amps will tell you the Watts. ( W = E x I = 12V x ?I = > ? Watts)

An excessive value will indicate a short to ground within the solenoid winding.

DC Solenoids are RL circuits.

DC circuits actually _do_ have impedance... it's just that it decays with time... and (usually) _very_ little time, at that. This means that DC impedance decays to pure resistance within milliseconds -- or a few seconds. ( larger systems -- ie big DC motors )

So, the system starts out with DC impedance -- and then promptly fades to _pure_ resistance. Hence the current is only choked back by* resistance*. ( Think milliseconds)


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## inetdog (Apr 13, 2016)

telsa said:


> DC circuits actually _do_ have impedance... it's just that it decays with time... and (usually) _very_ little time, at that. This means that DC impedance decays to pure resistance within milliseconds -- or a few seconds. ( larger systems -- ie big DC motors )
> 
> So, the system starts out with DC impedance -- and then promptly fades to _pure_ resistance. Hence the current is only choked back by* resistance*. ( Think milliseconds)


Another way of looking at it is that what is applied to the solenoid is not a DC voltage, it is a unipolar voltage pulse.
It goes from zero to nominal voltage at some time T, and the current moves rapidly toward a steady state value.
This step voltage can be expressed as a summation of an infinite number of sine waves of differing frequency, and it is those that interact with the inductance of the coil, not the "constant" DC.
Real world electricians take the simple stepped DC voltage approach and some engineers and physicists take the Fourier transform approach.


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## Moonshot180 (Apr 1, 2012)

its normal..heck some of the environments our solenoids are in have ambient temps well over 100 deg f....

some solenoids may be too hot to touch..doesn't mean that there is an issue w/ it.

While energized, get a current measurement, and see if it adds up to what the nameplate says.


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## JBoen (Jun 27, 2016)

Thanks all, i just want to know if its normal to get hot, i just dont wanna screw the new solenoid.

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## John Valdes (May 17, 2007)

My question would be, how hot is hot?


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## sbrn33 (Mar 15, 2007)

If it is latching why would it get hot?


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## inetdog (Apr 13, 2016)

sbrn33 said:


> If it is latching why would it get hot?


"It pulls and holds...." in the OP was not a reference to a latching solenoid.
It is energized the full time the engine is running.

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## Moonshot180 (Apr 1, 2012)

John Valdes said:


> My question would be, how hot is hot?


 
when the coil starts boiling the paint off of the coil cover...

seriously speaking I think most solenoids that we install, have different ratings on them..asco (for example) will list the normal ambient temperature range in the catalog cut sheets...and most often times, the fluid temp will be additive to the overal temp rating of the coil


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## Moonshot180 (Apr 1, 2012)

Here is an example..of an Asco..with the coil insulation information..


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## JBoen (Jun 27, 2016)

John Valdes said:


> My question would be, how hot is hot?


I think it will be around 40-50 degree celcius for 2 hours hold. 


sbrn33 said:


> If it is latching why would it get hot?


There is many types of fuel solenoid, this one is the fuel shut off solenoid. 3 wires, a black wire to ground, red wire goes to positive, white wire touches red wire for one sec to pull and hold the solenoid. When red wire disconnect from positive, it will stop holding. So i guess, the coil is working as a magnet while getting electricity from positive battery. Thats why it gets hot, perhaps?


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## JBoen (Jun 27, 2016)

Moonshot180 said:


> Here is an example..of an Asco..with the coil insulation information..


I think its the same concept with this solenoid. The problem is, im not sure if it will be able to tolerate with the engine temp.


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## daniel marini (8 mo ago)

nececito saber como conectarlo para que ande le doy 12v y no pega no se activa


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## John Valdes (May 17, 2007)

Translation:
"I need to know how to connect it so that it works, I give it 12v and it doesn't hit, it doesn't activate"
Try English Daniel.


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## gpop (May 14, 2018)

2 coils one high one low. High has to active to pull it in. Low holds it.

Chances are you are only wiring the low which will not pull it in and will end up smoking it. If you only wire the high it will pull in until it gets hot and burn up.

So make sure you wire both sides correctly


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## Marsh (11 d ago)

JBoen said:


> Hi again!
> 
> Today i have something that really confused me, whcih is solenoid fuel stop. It pulls and holds, but the thing is it gets hot. I dont know if this is normal, but the wiring was newly made according to this diagram. Is it really supposed to get hot ( 1 hour hold but still holdable with my hand)
> 
> ...


Hi,
Can you please tell how this solenoid works i want to test it and later ill make an AMF board for my generator.

Thanks and Regards


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