Things to know about your Onan generator
So I have a 4BGE Speg G Onan generator in my 1990 Winnebago Warrior. I've been struggling for about a year to get it running again. First it was a split fuel line back at the tank. Then it would run, but shut down. Replaced the ignition control module with a used one, ran for a while and then shut down again.
I thought I would share some thoughts on these things, now that I know my way around them like the back of my hand.
The mechanical side of these things is pretty bullet proof. That is, the engine is pretty well made, at least the older ones. With a couple of exceptions.
When they switched these generators from points ignition to electronic ignition, they installed a plastic rotor (looks like a propeller) deep inside the genset, between the motor and generator halves. If rodents build a nest inside your generator, and you try to fire up the generator, this rotor can easily get snapped off by the nest debris. This did not happen to me, fortunately, but it is a common problem with these gensets. Unfortunately in order to replace this rotor you have to split the generator in half to replace it.
There are only 6 electrical parts that make the generator go:
Coil
Ignition Control Module
Starter
Voltage Regulator
Control Board
Starter Solenoid
The coil you can now buy aftermarket replacements for far less than what some sell them for - $45 vs. $145. I used this one:
https://www.amazon.com/gp/product/B07BFXC9V4
The OEM starter has a fragile plastic keeper system that forces the starter gear to disengage. These last about 5 years and disintegrate. There are now aftermarket starters that have simplified this assembly and use all metal parts. They are also much cheaper than OEM versions ($35 vs. $133). I used this one:
https://www.dbelectrical.com/products/starter-onan-191-1630-191-1667-191-2132-1975-on.html
Unfortunately the Ignition Control Module is Onan-specific. I bought it here for $103:
http://www.partsfortechs.com/asapcart/1660821-ignition-control-onan-p-350.html
The Voltage Regulator and Control Board you can buy from Flight Systems:
https://www.flightsystems.com/
You can also send your VR and CB to them and they will test them for $35 each. These parts are expensive - $200+ each. And, if you have to buy new ones from them, they will waive the test fee.
The good news is all of these parts are relatively easy to replace - especially if you remove the genset from the RV. There is a trick with the Ignition Control Module - you have to turn the motor over by hand until the short cooling fit lines up with the ICM - otherwise you can't remove it from the genset housing.
Except for the VR and CB, you can replace all the rest of the components for a couple of hundred bucks if you do it yourself. Instead of farting around testing and trying (which ultimately fragged my starter, which is why I had to replace it also) I would have been better off, once I identified I had a spark problem (using a spark tester) if I had just replaced all of those components from the get-go.
To keep your generator running, it is IMPERATIVE that you run it monthly. I run mine for half an hour under load.
I used to think this was just an optional thing. You know "exercise" the generator. Right. But it is critical for a couple of important reasons.
First of all, you must keep the slip rings clean. You should measure the resistance between the two brushes - if you get more than 80 ohms you need to clean your slip rings. Flight Systems makes a "slip stick" that will help you polish them clean - it's about $20. I used it on mine and went from 80 ohms down to 20. By running your generator often, it will self-polish those rings.
Why is this important? High resistance on the slip rings will destroy the voltage regulator. That's about $250 to replace. So, exercise your genset monthly and keep those slip rings clean or you will be spending a lot of money!
The second thing is you must keep fresh gas running through the carburetor. Especially with today's ethanol gas. One of the big killers of RV generators and performance is gummed-up carbs. Onan doesn't even recommend rebuilding these anymore - they recommend replacement. That's $300+. Run your genset under load every month for half an hour and the heat and vibration and fresh gas will keep the internals nice and clean.
Steve
I thought I would share some thoughts on these things, now that I know my way around them like the back of my hand.
The mechanical side of these things is pretty bullet proof. That is, the engine is pretty well made, at least the older ones. With a couple of exceptions.
When they switched these generators from points ignition to electronic ignition, they installed a plastic rotor (looks like a propeller) deep inside the genset, between the motor and generator halves. If rodents build a nest inside your generator, and you try to fire up the generator, this rotor can easily get snapped off by the nest debris. This did not happen to me, fortunately, but it is a common problem with these gensets. Unfortunately in order to replace this rotor you have to split the generator in half to replace it.
There are only 6 electrical parts that make the generator go:
Coil
Ignition Control Module
Starter
Voltage Regulator
Control Board
Starter Solenoid
The coil you can now buy aftermarket replacements for far less than what some sell them for - $45 vs. $145. I used this one:
https://www.amazon.com/gp/product/B07BFXC9V4
The OEM starter has a fragile plastic keeper system that forces the starter gear to disengage. These last about 5 years and disintegrate. There are now aftermarket starters that have simplified this assembly and use all metal parts. They are also much cheaper than OEM versions ($35 vs. $133). I used this one:
https://www.dbelectrical.com/products/starter-onan-191-1630-191-1667-191-2132-1975-on.html
Unfortunately the Ignition Control Module is Onan-specific. I bought it here for $103:
http://www.partsfortechs.com/asapcart/1660821-ignition-control-onan-p-350.html
The Voltage Regulator and Control Board you can buy from Flight Systems:
https://www.flightsystems.com/
You can also send your VR and CB to them and they will test them for $35 each. These parts are expensive - $200+ each. And, if you have to buy new ones from them, they will waive the test fee.
The good news is all of these parts are relatively easy to replace - especially if you remove the genset from the RV. There is a trick with the Ignition Control Module - you have to turn the motor over by hand until the short cooling fit lines up with the ICM - otherwise you can't remove it from the genset housing.
Except for the VR and CB, you can replace all the rest of the components for a couple of hundred bucks if you do it yourself. Instead of farting around testing and trying (which ultimately fragged my starter, which is why I had to replace it also) I would have been better off, once I identified I had a spark problem (using a spark tester) if I had just replaced all of those components from the get-go.
To keep your generator running, it is IMPERATIVE that you run it monthly. I run mine for half an hour under load.
I used to think this was just an optional thing. You know "exercise" the generator. Right. But it is critical for a couple of important reasons.
First of all, you must keep the slip rings clean. You should measure the resistance between the two brushes - if you get more than 80 ohms you need to clean your slip rings. Flight Systems makes a "slip stick" that will help you polish them clean - it's about $20. I used it on mine and went from 80 ohms down to 20. By running your generator often, it will self-polish those rings.
Why is this important? High resistance on the slip rings will destroy the voltage regulator. That's about $250 to replace. So, exercise your genset monthly and keep those slip rings clean or you will be spending a lot of money!
The second thing is you must keep fresh gas running through the carburetor. Especially with today's ethanol gas. One of the big killers of RV generators and performance is gummed-up carbs. Onan doesn't even recommend rebuilding these anymore - they recommend replacement. That's $300+. Run your genset under load every month for half an hour and the heat and vibration and fresh gas will keep the internals nice and clean.
Steve
