Troubleshooting Onan Emerald 3 Generator Power Issues in 1987 Chieftain 33RU

[DaPreacherMan]

1987 chieftain 33RU.
I’m getting no power to start the onan emerald 3 generator. When I try to start via switch on the dash - nothing. Like it has no power.
I’m new to this stuff so be kind.
I’ve emailed Cummins for manuals and wiring diagram

Here’s some pics if it helps

 

[DaPreacherMan]

I’m guessing the two white wires go to the electric choke, but there is a white wire like a ground on the stator case.

 

[Morich]

Sounds like you have a good one to chase!
One big problem is that we get NO online wiring for any Rv before 1990! But they do keep things much the same for years, so maybe we can cut a corner and look at info for 1990 and see if it fits your RV?
But I suggest going to the real basics first and make sure that is right as the choke is not involved until you get it to crank!
How's the experience level on cars and how they start? Generators are somewhat the same as it uses a button inside like a car uses a key. That sends a signal to a solenoid with a coil inside. When the solenoid gets power, it moves a set of big contacts to close to put the power from a big battery cable to the starter on the generator.
But a generator also often has a switch right on the generator that we can push to start it from there! I think I see that switch just below the name "Onan genset"?
Do I see that labeled start and stop? That should work like the key in a car to make the genset crank!
And it is less apt to have corrosion, loose wires and such!
First step might be to find the big battery cable that should bring 12VDC from the batteries to the genset. Nothing works if no 12olts on that big cable, so I favor checking that first.
Then if you push the button to start and nothing happens, you need to check the small wires as they tell the solenoid to close and send that 12V on to the starter to crank the engine.
The drawings for the 1990, show a 6 pin plastic connector that should have four wires that are labeled on the side. It's a guess but if you find that connector it may still be the same?

Guessing but I think this set of wires will come from the inside switch with the two I marked being what controls the starter solenoid/relay.
If you push the button on the genset, you should hear a click as the solenoid closes. same if somebody inside pushes the start button!
But when/if you hear it click, it has to have 12V on the big cable for it to pass on to the generator starter!
I'm not a good generator mechanic and know little beyond that but that may be enough to get it to at least try!

And trying is always a good place to start!

 

[DaPreacherMan]

Sounds like you have a good one to chase!
One big problem is that we get NO online wiring for any Rv before 1990! But they do keep things much the same for years, so maybe we can cut a corner and look at info for 1990 and see if it fits your RV?
But I suggest going to the real basics first and make sure that is right as the choke is not involved until you get it to crank!
How's the experience level on cars and how they start? Generators are somewhat the same as it uses a button inside like a car uses a key. That sends a signal to a solenoid with a coil inside. When the solenoid gets power, it moves a set of big contacts to close to put the power from a big battery cable to the starter on the generator.
But a generator also often has a switch right on the generator that we can push to start it from there! I think I see that switch just below the name "Onan genset"?
Do I see that labeled start and stop? That should work like the key in a car to make the genset crank!
And it is less apt to have corrosion, loose wires and such!
First step might be to find the big battery cable that should bring 12VDC from the batteries to the genset. Nothing works if no 12olts on that big cable, so I favor checking that first.
Then if you push the button to start and nothing happens, you need to check the small wires as they tell the solenoid to close and send that 12V on to the starter to crank the engine.
The drawings for the 1990, show a 6 pin plastic connector that should have four wires that are labeled on the side. It's a guess but if you find that connector it may still be the same?
View attachment 2410898

Guessing but I think this set of wires will come from the inside switch with the two I marked being what controls the starter solenoid/relay.
If you push the button on the genset, you should hear a click as the solenoid closes. same if somebody inside pushes the start button!
But when/if you hear it click, it has to have 12V on the big cable for it to pass on to the generator starter!
I'm not a good generator mechanic and know little beyond that but that may be enough to get it to at least try!

And trying is always a good place to start!

Thanks for the direction.
I'll need to start investigating. I don't think it is getting any power at all. The switch on the center console under the dash doesn't seem to do anything.

I'm wondering if it is a user error.
Can anyone help verify that the AUX Battery switch needs to be in the on or off position before trying to start the generator from the dash switch?

 

[Morich]

guessing that is not the problem but bears testing!
I think that switch is meant to connect the battery we now call coach battery to the normal chassis (start battery that we have on cars and trucks. Aux is short for auxiliary and that is a term from boating for when we have a battery for starting and then a second for other things like lights, etc. So the term got used in RV and now we find it called chassis battery for the normal one and coach battery for things added to make an RV!
I "think" turning that switch on will connect both batteries together.
Good for letting the RV engine get some charge put into the coach/aux battery as we drive and both are connected to the engine alternator.
Downside of that older system was forgetting to turn it off when we stopped and used the RV to camp without hookups as we would run both batteries down and have to have a jump start to get the engine going!
Now they have a system that does that connect automatically, to keep us from forgetting!
One way, you might try is starting the RV engine, that gets the alternator putting out power like a normal truck. Then flip that switch on and that might connect the other battery we call aux or coach! I think doing that may make ALL the electrical stuff, both for the truck part and also the inside RV parts gets power.
Keep in mind this is from long lost memory, so test it before believing it too far?
One good move when trying to get any RV electrical part to work the first time , is to start the engine as that alternator gives you more power than just the battery. Then if you close that switch, I think that will also pass the alternator power on to the things added for an RV.
One of the things about RV is there are some things that run off the start battery and some off the coach, so trying to get good power going to BOTH can head off some trouble!
But maybe hang a tag on that switch to tell you to turn it off if you go camping where you might get stranded if both run down at the same time!
If not on hand, this should take you to an online owners manual:

https://www.winnebago.com/Files/Files/Winnebago/Resources/OperatorManuals/Operator1987/87Winnebago-Itasca.pdf

Page 3-1 explains some of what I was talking and liable to be more accurate than my memory!
Lots of good stuff there but most of us read it and forget it so we keep the book handy!
Are you beginning to melt off up there?

 

[DaPreacherMan]

Well, I did some RV archeology and found this today…

 

[Morich]

Good find that looks in really good shape for a forty year old book!
I've never had hands on one of those, so how complete does it go? Anything like wiring drawings or troubleshooting ideas?
Actually on generators I've owned, they have been so little trouble that I only know the really big points beyond the wires!
Looks like it should be a big help to you!

 

[DaPreacherMan]

Getting closer. It has spark (i will probably change the plug anyways), just need to find where the fuel comes from. I took the blue fuel hose that goes to the fuel pump, and it’s dry.

 

[DaPreacherMan]

 

[Morich]

Getting spark? Does that mean you have moved beyond getting it to crank?
Point on the fuel is that it is likely to need more than 1/4 tank full on the RV. Many are set up to avoid letting us run the RV tank dry when using the genset, so needs that much to draw fuel to the genset!
But there is a pretty good bet that there is an inline fuel filter and that might be a good place to check for fuel problems?
Maybe underneath and possibly along the frame?
I hear about them hiding next to the frame and being easy to miss!

 

[RayIN]

Jot down the model# of your Onan genset, then go to ONAN PDF MANUAL Links
to download the manuals for your model#.
I assume you've already seen: https://www.cummins.com/generators/rv-generators/rv-generator-manuals

 

[Zoohelp]

On my 2000 Itasca the aux switch does indeed connect the house batteries to the engine battery for starting it if engine battery is dead. However it does not stay on. You need to hold it. If the rv house battery switch is on, the engine will charge the house batteries. This should be turned off when in storage. Note that there will still be parasitic drain and the negative cable should be taken off if not connected to power or a trickle charger connected. As far as fuel goes, my generator will not get fuel if tank is less than a 1/4 tank. Have you tried opening the drain on the carburetor bowl to see if it's getting fuel?

 

[DaPreacherMan]

Thanks all for your contributions. I was sick most of February, but feeling great now.
quick updates. I will have to revisit the generator again. I believe one of the contributing factors is a faulty 12v battery DC line to start the generator. When i sprayed some contact cleaner, it would turn over, but when it dried, it stopped turning over, indicating that the power is there, its just not moving past the wire and into the post.

 

[Morich]

Yes, sounds like moving in the right direction. I first want to verify power is getting to the area of the generator and reliable. Fuel an other points are good but not important until we get it to crank?
Crank, fuel, and then spark and air are the order I want to check.
The cranking on a generator is somewhat like most gas engines in that it will need power getting to two points as a first step.
Are you familiar with teh way a solenoid works? Just a switch that moves big contacts but we use small electircal wires instead of our hand.
If totaly new to the idea, look for the big batteryc able comiong to the generator area. That is where you have to have 12VDC full time as it is waiting for the contacts to close to pass that power tot he starter. I might expect that to be near or on the generator starter??
Good 12VDC power there, then we have to get power on small wires to make the solenoid contacs close. There are likelly to be two small wires on the solenoid. Possibly only one small if the ground is made through the solenoid mounted to metal?
But what you need there is to see 12VDC come alive on the small wire when either of the Start" buttons are pushed. If it is not getting 12V to the small wire on the solenoid, try both the button on the generator as well as the one inside. Maybe one works but not the other?
But I may be seeing a problem with a fuse in one of your pictures?

Is it the lighting or is this small glass fuse really black? Not sure where it fits in the whole idea but this seems it might be blown and is it near the start switch on the controls? If not burned, it sure looks corroded from here???
Good to hear you are feeling better, now go work---- so you can play later??

 

[DaPreacherMan]

Yes, sounds like moving in the right direction. I first want to verify power is getting to the area of the generator and reliable. Fuel an other points are good but not important until we get it to crank?
Crank, fuel, and then spark and air are the order I want to check.
The cranking on a generator is somewhat like most gas engines in that it will need power getting to two points as a first step.
Are you familiar with teh way a solenoid works? Just a switch that moves big contacts but we use small electircal wires instead of our hand.
If totaly new to the idea, look for the big batteryc able comiong to the generator area. That is where you have to have 12VDC full time as it is waiting for the contacts to close to pass that power tot he starter. I might expect that to be near or on the generator starter??
Good 12VDC power there, then we have to get power on small wires to make the solenoid contacs close. There are likelly to be two small wires on the solenoid. Possibly only one small if the ground is made through the solenoid mounted to metal?
But what you need there is to see 12VDC come alive on the small wire when either of the Start" buttons are pushed. If it is not getting 12V to the small wire on the solenoid, try both the button on the generator as well as the one inside. Maybe one works but not the other?
But I may be seeing a problem with a fuse in one of your pictures?
View attachment 2428964
Is it the lighting or is this small glass fuse really black? Not sure where it fits in the whole idea but this seems it might be blown and is it near the start switch on the controls? If not burned, it sure looks corroded from here???
Good to hear you are feeling better, now go work---- so you can play later??

Thanks again. The fuse is fine, just a dark pic. With everything here being 40 years old, I think the switch definitely needed exercised, but then I lost 12vdc to the switch from the contact area from the batt cable to the 12vdc+ post inside this case.

I'm not too concerned about it as long we are guaranteed shore power, but I have plans to stay in this rig at multi-day RC plane events this year, so that will be more than likely boondocking or with 15A power only. So this issue while not a priority, is still stage 2 mission critical.