Generator only starts in cold weather

[KJcachers]

Help. Had this problem for quite a while now but want to make it go away. The Onan RV QG 4000 will only crank and start in cold temperatures. Works fine every fall and winter but once springs warmer temps roll around it won’t even crank. Wait until fall and works like a charm. Any ideas or do I need to spend some money at a Cummins repair shop?

[JLeising]

True for both the remote start switch and the start switch on the generator?

If so, as it doesn’t even crank, maybe try jumping power direct to the starter?

[KJcachers]

Originally Posted by JLeising

True for both the remote start switch and the start switch on the generator?

If so, as it doesn’t even crank, maybe try jumping power direct to the starter?

Same from both switches. I hear something engaging like a primer pump but never cranks. Fast flicker on the lights show as a Cranking error code lol

[formerFR]

there could be several things going on here, and we may not have enough information about 'exactly' when and under what circumstances this is happening, as most generator, or any type of engine, certainly would seem to start more readily in warm temps.

So, could it be that in all the situations you describe, that the fuel level for the RV was less than 1/4 at that time, but more when it would crank?

[KJcachers]

Originally Posted by formerFR

there could be several things going on here, and we may not have enough information about 'exactly' when and under what circumstances this is happening, as most generator, or any type of engine, certainly would seem to start more readily in warm temps.

So, could it be that in all the situations you describe, that the fuel level for the RV was less than 1/4 at that time, but more when it would crank?

I keep the tank full when parked in case I need to make a run for the hills or just want to go camping quick, on a whim. It’s definitely temperature related. I’m wondering if there is some kind of relay somewhere that is sticking or changing position due to being warmer that opens or closes as it should when the temps drop 🤷*♂️
I call the local
Cummins dealership a year ago on this issue and left a message and they never called me back so I’m nervous about trying them again now with all the other BS going on in the world.

[JLeising]

If this link works, shows an Onan generator electrical schematic. May not be for your generator, however:

https://images.app.goo.gl/1rgxd98TxVSE29is9

Relay K1 is the starter relay. That is what I would be most suspicious of. Jumping 12 volts direct to the generator would bypass this relay. If it cranks - the relay or the circuit driving it likely is the cause of the problem.

[formerFR]

alright, so, when you say it won't crank, are you continuously holding down the Start Switch for long enough, maybe sometimes a minute or more?

[KJcachers]

Originally Posted by JLeising

If this link works, shows an Onan generator electrical schematic. May not be for your generator, however:

https://images.app.goo.gl/1rgxd98TxVSE29is9

Relay K1 is the starter relay. That is what I would be most suspicious of. Jumping 12 volts direct to the generator would bypass this relay. If it cranks - the relay or the circuit driving it likely is the cause of the problem.

Thanks, I’ll give this a look. Is K1 on the control board? Perhaps it needs a tap with a screwdriver or small hammer ! [emoji1]

[JLeising]

Originally Posted by formerFR

alright, so, when you say it won't crank, are you continuously holding down the Start Switch for long enough, maybe sometimes a minute or more?

Wow! Much easier fix than where I was leading you! Hope this works!

[KJcachers]

Originally Posted by formerFR

alright, so, when you say it won't crank, are you continuously holding down the Start Switch for long enough, maybe sometimes a minute or more?

Never that long but 10-20 seconds easily with no cranking. Cranks right away in cold weather

[JLeising]

Originally Posted by KJcachers

Thanks, I’ll give this a look. Is K1 on the control board? Perhaps it needs a tap with a screwdriver or small hammer ! [emoji1]

Sorry, I don’t know. I haven’t had to troubleshoot mine yet. On cars, it is often mounted on the starter. If not there a fairly heavy duty cable from the starter should lead to the relay. (Called the starter solenoid on cars - which also engages the starter gear into the flywheel gear.)

FYI and good luck -

[KJcachers]

Originally Posted by JLeising

Sorry, I don’t know. I haven’t had to troubleshoot mine yet. On cars, it is often mounted on the starter. If not there a fairly heavy duty cable from the starter should lead to the relay. (Called the starter solenoid on cars - which also engages the starter gear into the flywheel gear.)



FYI and good luck -

Thanks, I’ll update this thread when I get a result/fix

[JLeising]

Tapping is a great way to troubleshoot. While you’re at it, try tapping the starter motor - possible hung up brushes.

[jkoenig24]

As already mentioned, try connecting a good 12VDC battery directly to the starter and see if that will get the generator cranking. Since that QG generator is GASOLINE powered, I'd get a can of Seafoam additive and see if that gets the gunk out. If it does, after letting the generator run UNDER LOAD for an hour or so, change the fuel filters and continue using the Seafoam with each gas fill up until you've used it all up. Then, fall back to a few Seafoam uses a year to maintain the fuel system.

[Tom Hall]

Here's my guess. The generator in my boat wouldn't start because the carburetor was gummed up. I'm thinking your carb is gummed up, but when it's cold, the choke circuit is taking over to supply fuel. Also, how is your oil level? Many gens won't start if the oil level is low. Good luck.

[ActionJackson]

Reading this thread make me dizzy. Ya’ll need to get the terminology correct. If some motor does not “ crank”, that means it is not spinning, making no noise, not “ turning over”
and no amount if sea foam will make it start and “ Run”.
If the motor is “ cranking ( turning over, making a motor noise ) and not “ starting” that is a different situation with an entirely different method of troubleshooting.

[Tom Hall]

I have been in the auto repair business for 48 years and I was throwing that out because most people don't know the difference between "not starting" and not "not cranking".

[ActionJackson]

Originally Posted by Tom Hall

I have been in the auto repair business for 48 years and I was throwing that out because most people don't know the difference between "not starting" and not "not cranking".

Yeah, I hear ya. Drives me crazy.

[BehindBars]

Originally Posted by ActionJackson

Reading this thread make me dizzy. Ya’ll need to get the terminology correct. If some motor does not “ crank”, that means it is not spinning, making no noise, not “ turning over”
and no amount if sea foam will make it start and “ Run”.
If the motor is “ cranking ( turning over, making a motor noise ) and not “ starting” that is a different situation with an entirely different method of troubleshooting.

I totally agree. It’s near impossible to troubleshoot a problem remotely when the parties have different understandings of the terminology.