Northern Lights Generator starts but won’t run

[FatDaddyG]

Hello, I’m having trouble with my 6KW NL generator. It will start but shuts down within a couple of minutes randomly. After a few starts it will also shut down immediately after releasing Bypass switch. I’ve disconnected both coolant switches, oil pressure switch and exhaust temp switch with no change. Also, I’ve pulled and tested all 4 relays and reinstalled in random order twice with no change (all relays tested good). I’m down to looking for skinned ground wires. Something is tripping the shutdown relay but not any of the things I’ve disconnected. What am I missing?

[s/v Jedi]

Originally Posted by FatDaddyG

Hello, I’m having trouble with my 6KW NL generator. It will start but shuts down within a couple of minutes randomly. After a few starts it will also shut down immediately after releasing Bypass switch. I’ve disconnected both coolant switches, oil pressure switch and exhaust temp switch with no change. Also, I’ve pulled and tested all 4 relays and reinstalled in random order twice with no change (all relays tested good). I’m down to looking for skinned ground wires. Something is tripping the shutdown relay but not any of the things I’ve disconnected. What am I missing?

Time to test with the multimeter. I have the same genset and only had trouble with the relays. It would restart itself during shutdown or I could start it by shaking it

There may be a sensor that works in reverse, i.e. taking the wire off may not disable that error. I’m not sure really but with the multimeter it should be easy to find?

[OldGreyB]

You need to be systematic in your fault finding.

Per your attached schematic ,(and Sv Jedi comment) the oil pressure switch opens on run, and closes on low oil pressure, so disconnecting it does not check it. This is the first sensor to check correctly:

Disconnect the grey wire to the oil pressure sensor.
Multimeter in OHMS and clip multimeter to the sensor tab and ground.
Meter should read Continuity to ground.
Start the generator.
1)Meter should read OPEN to ground on engine running ( YES / NO )
2)Let generator run, does it continue to run? (YES / NO)
3) Does the meter go back to Continuity to ground after a while ? (YES/NO)
4) What oil pressure does your oil pressure gauge indicate?
Stop generator.


A) If the generator continued to run, then it's possibly the pressure switch circuit OR low oil pressure. Need to validate which it is.
B) If the generator stopped running, it's not the oil pressure switch

Report back on the three (YES /NO) and oil pressure , if needed I'll send some further tests.

[FatDaddyG]

I removed all the relays then with meter grounded to block and probed into 86 on the Shut Down Relay socket. I found ground then disconnected oil pressure switch and lost ground, proving none of the other sensors (coolant temp or exhaust temp) are grounded. Engine starts and runs great with oil pressure switch disconnected but shuts down immediately upon releasing Bypass.

[FatDaddyG]

Thanks! I appreciate your assistance…

Disconnect the grey wire to the oil pressure sensor.
Multimeter in OHMS and clip multimeter to the sensor tab and ground.
Meter should read Continuity to ground.
* YES - Meter shows continuity with .73 Ohm
Start the generator.
1)Meter should read OPEN to ground on engine running ( YES / NO )
* YES - Meter shows OL with engine running.
2)Let generator run, does it continue to run? (YES / NO)
* NO - Started engine 3 times. First time it ran for 20 seconds after releasing Bypass then shut down. Next two times it shut down immediately upon release of Bypss.
3) Does the meter go back to Continuity to ground after a while ? (YES/NO)
YES - Meter returned to continuity with .73 Ohms after shutdown
4) What oil pressure does your oil pressure gauge indicate?
* Gauge reported 45 psi upon starting then settled to around 30 psi until shutdown.
Stop generator.


A) If the generator continued to run, then it's possibly the pressure switch circuit OR low oil pressure. Need to validate which it is.
B) If the generator stopped running, it's not the oil pressure switch

Report back on the three (YES /NO) and oil pressure , if needed I'll send some further tests.[/QUOTE]

[FatDaddyG]

Originally Posted by s/v Jedi

Time to test with the multimeter. I have the same genset and only had trouble with the relays. It would restart itself during shutdown or I could start it by shaking it

There may be a sensor that works in reverse, i.e. taking the wire off may not disable that error. I’m not sure really but with the multimeter it should be easy to find?

This is my first but it “looks” pretty straight forward but I’m clearly missing something

[cr180]

If I’m reading the schematic correctly: Bypass switch energizes run relay, rr, closing rr contact to energize fuel control solenoid and same contact in series with shutdown relay, sdr, normally closed (nc) contact seals in and keeps rr energized when bypass switch opened. Note with interest the two diodes. Lastly the stop position on the control switch or any of the temp or oil pressure sw energizes sdr, opens the sdr nc contact which trips rr and de-energizes the fuel control solenoid stopping engine. Weird circuit.

So could be control switch. Might try lifting grey wire off control switch. Are you sure sdr actually picking up (energizing) to cause engine to stop? Could be diode between sdr and rr misbehaving causing rr to de-energize. Or as you are already suspecting some faulting wiring.

[cr180]

The more think about it, check the diode.

[SailFastTri]

Change your fuel filters - primary and secondary
Edit - NL uses a 2-micron secondary (if I’m not mistaken)

[IRENE]

We were experiencing un commanded shutdowns occasionally on our NL 9kw. All of the sensors and relays tested good. I replaced the round black circuit breaker in the box, I think it is marked fuse or 15a. No un commanded shutdowns since.

You can experiment with a 15a fuse in place of the breaker if you don't have a spare breaker aboard…just tape it well.

[OldGreyB]

From Post #4
"I removed all the relays then with meter grounded to block and probed into 86 on the Shut Down Relay socket. I found ground then disconnected oil pressure switch and lost ground, proving none of the other sensors (coolant temp or exhaust temp) are grounded. Engine starts and runs great with oil pressure switch disconnected but shuts down immediately upon releasing Bypass."

From Post #5
1)Meter should read OPEN to ground on engine running ( YES / NO )
* YES - Meter shows OL with engine running.
2)Let generator run, does it continue to run? (YES / NO)
* NO - Started engine 3 times. First time it ran for 20 seconds after releasing Bypass then shut down. Next two times it shut down immediately upon release of Bypss.

From Post# 10
The 15A breaker could be intermittent

We now know:
1) Good power on the bypass circuit (15A breaker withstanding)
2) Bypass circuit is working
3) The oil pressure switch circuit is working as designed
4) The coolant and exhaust temp circuits are working as designed
5) Ground is good to the run relay
6) Stop switch is not in stop position
7) May be intermittent / loose / corrosion as you have had 20 second run



Next tests are to ensure the "run" circuit is functioning or not. This includes the run relay contacts, the shutdown relay contacts and the run circuit diode:

Method:
A) With Multimeter on Volts, one leg clipped to good ground.

B) Multiple separate tests with engine running and Bypass ON in each case:

C) Establish +12Vdc on the selected probe point then release the By Bass switch and record YES / NO

1) Probe on Run Relay #30 +12Vdc YES / NO ?

2) Probe on Run Relay #87 +12Vdc YES / NO ?

3) Probe on Shutdown Relay #30 +12Vdc YES / NO ?

4) Probe on Shutdown Relay #87b +12Vdc YES / NO ?

5) Probe on Run Relay #85 +12Vdc YES / NO ?


See PDF (Northern Lights Gen Run Test Point Dwg) attached with test points noted.

Try those tests and post back. During testing it may show a fault in the wiring or contact to relay base within the run circuit.
Others may also have ideas from above tests.

[Renegde_Sailor]

If the engine is running fine with the oil pressure switch disconnected I would venture to say that is your problem.

The switch should stay closed making contact to ground until the engine starts and comes up to pressure, you need to check it with the engine running, if it still shows ground with full oil pressure going to it, there you go.

However also you need to check and see that you actually have good oil pressure, a clogged filter can cause this.

These sensors are known for going bad across a wide array of engines, most are constructed with nothing more than a spring and a contact that when the engine comes up to pressure it pushes the plunger in breaking the contact. If the plunger becomes stuck it will fail to function.

[OldGreyB]

Correction to method in my post #11

The run diode will block back feed from the by pass switch, so with the By Pass switch ON, you can check each test point of the circuit:

Method:
A) With Multimeter on Volts, one leg clipped to good ground.

B) Multiple separate tests with engine running and Bypass ON in each case:

C) Establish +12Vdc on the selected probe point and record YES / NO

[FatDaddyG]

Yes… I actually like how simple it all is with the relays. Hearing folks on another forum say it ends up being the stupid 15A breaker intermittently dropping power to all relays due to vibration. I’ve meter tested each relay and proved out anything going to ground on the SDC so about to rustle up a 15A breaker.

[skipperpete]

Be careful to look closely at both the relay you take out and the one you plan to install, there a few variations with the little bosch type relays depending on how the circuit is wired and they seem identical at a glance