Northern Lights Stop-Solenoid stopped working

[Looking Glass]

The stop-solenoid on our NL generator stopped operating while the generator was in use. The solenoid works when I hook it up to a battery but it does not activate when I try to start the engine, nor when I press the warm-up button.

I can get the generator to run by manually pulling the solenoid arm, but of course the generator stops as soon I let go. There are no loose wires.

Any ideas?

 

[Captain Ralph]

The run solenoid will not engage or stay engaged if there is a fault.
The by-pass button will allow the run solenoid to engage while starting but an over temp (exhaust, coolant) or no oil pressure will not let it run.

Next
A loose connection to the relay or bad relay. Try re-seating the run relay and ensure a wire does not poke out the back of the receptacle.

 

[Looking Glass]

The run solenoid will not engage or stay engaged if there is a fault.
The by-pass button will allow the run solenoid to engage while starting but an over temp (exhaust, coolant) or no oil pressure will not let it run.

Next
A loose connection to the relay or bad relay. Try re-seating the run relay and ensure a wire does not poke out the back of the receptacle.

Thanks for the input. I jumped out the oil pressure sensor to no effect. I am not sure how too test the temperature other than I let it cool off completely and it didn't help.

I do not know where the run relay is. The positive and negative from the solenoid run into a maze of wires that I can't trace. Would it be in the main service panel where the start and pre-heat switches are located.

 

[Looking Glass]

Update: I could not find the run relay at the service panel where the start and preheat switches are located. I have a GSCM start controller installed, which I never use. Could this have replaced the run relay? If it is bad, could it cause my problem?

 

[zigzag930]

On my NL's generators there is a solenoid/fuel cutoff device on the left side of the high pressure fuel pump. It has one terminal (12V) going to it. If you have the same setup, when you hold the "Preheat" switch in and release it (not cranking the engine) you should feel this solenoid click.

Mine would not as the wire connected to it was not making full contact. Cleaned, tightened and off to the races.

If not clicking, check for 12v there at the terminal. No 12v?, follow the wires back until you find the culprit.

 

[Captain Ralph]

I do not know where the run relay is.

What year, size or model number. I'll find a schematic.

Till then; there is a box on top of the electrical end, houses the AVR also.
Relays are usually in there.

Zigzag930 has a great suggestion also.

 

[Looking Glass]

What year, size or model number. I'll find a schematic.

Till then; there is a box on top of the electrical end, houses the AVR also.
Relays are usually in there.

Zigzag930 has a great suggestion also.

Here is a picture of where the AVR and relays are. The Model is Northern Lights M-854. I believe it is installed in 1979. Thanks for your help.

 

[zigzag930]

Relays should be as follows:

SDR Shutdown Relay
PHR Pre-heat Relay
RR Run Relay
SR Strart Relay

Does that help?

 

[Looking Glass]

Relays should be as follows:

SDR Shutdown Relay
PHR Pre-heat Relay
RR Run Relay
SR Strart Relay

Does that help?

Yes, thanks. Are they identical relays. Can I swap the relay with another to see if it changes the problem?

 

[zigzag930]

I believe all but the SDR are identical. Looking at the schematics there is something showing different on the SDR, so not sure about that one.

 

[Looking Glass]

I switched the other three relays around, but it made no difference. Seems unlikely that multiple replays failed.

 

[piripucha]

I had the same problem in my 844 NL, the first time it was one of the Temp senders that was bad so it did not let the solenoid get any voltage. The second time it was the shaft of the solenoid that had some rust and this prevented it to engage. Try to send voltage directly. If the solenoid engages then you have a bad temp or pressure sender. ,. In my case it was the Temp sender that is located on the front above the pulley, I belive if you disconnect it it will isolate such sender. I hope this helps t

 

[Looking Glass]

I had the same problem in my 844 NL, the first time it was one of the Temp senders that was bad so it did not let the solenoid get any voltage. The second time it was the shaft of the solenoid that had some rust and this prevented it to engage. Try to send voltage directly. If the solenoid engages then you have a bad temp or pressure sender. ,. In my case it was the Temp sender that is located on the front above the pulley, I belive if you disconnect it it will isolate such sender. I hope this helps t

Thanks. My solenoid works if I hook it up directly to 12 volts. I was wondering how to test the temp sender. I have two right next to each other, I think. At least it looks that way. They both go into the bottom of the water reservoir on the opposite side of the pulley.

 

[Captain Ralph]

I have two right next to each other, I think.

Some gen-sets came with an alarm sender installed and a remote gauge sender.
You have to id the wire to them or id the sender it self to determine witch one is what.

 

[Captain Ralph]

My solenoid works if I hook it up directly to 12 volts.

And does not engage with the by-pass switch enabled?
A bad relay or loose/bad wire somewhere.

Homeport Phila

Why are the good bugs so far aweigh??

 

[Looking Glass]

I just noticed that none of the gauges work either (temp, oil, volts). They are not located in the generator room so I did not notice it before.

 

[Captain Ralph]

I just noticed that none of the gauges work either (temp, oil, volts). They are not located in the generator room so I did not notice it before.

You have some loose/open wires somewhere.

 

[cb48lrc]

Check the 12 volt circuits breaker

 

[Looking Glass]

After countless hours staring at the schematic and fooling with the generator, I finally found the problem, It was a loose ground wire on the fuel rack solenoid.

There are three wires connected to the negative terminal on the fuel rack solenoid. I guess it acts as a ground terminal for the relays. One of the wires was in it's crimp connector but it wasn't making contact. It must have vibrated loose enough to lose ground but not so loose that it was visibly disconnected.

I had decided to clean up all the connections and that was when I noticed the loose wire. It took all of two minutes to fix.

Thanks to everyone for helping me walk through this problem!