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Ask Hank F. Your Own Question
Hank F.
Hank F., RV tech - emphasis on gensets
Category: RV
Satisfied Customers: 15198
Experience:  RV tech since the beginning of the millenium.
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I'm looking onan generator (rv) expert. I understand

Customer Question

I'm looking for an onan generator (rv) expert. I understand there is one out there by the name of Hank, but if you're not hank and know onan rv generators please respond.
Submitted: 2 years ago.
Category: RV
Expert:  Hank F. replied 2 years ago.
Hello, thank you for requesting me.
What is the full model number of the genset, exactly as it is written on the data label?
What is the problem you are having?
Customer: replied 2 years ago.
Hi,Model # *****(c)efa26100m. serial # ***** I'm on the road tomorrow so I've been asking around a lot. It sounds like I may need to replace the carb. The unit starts and runs fine until put under load. Then it shakes and quakes and sputters. I checked the fuel filter and line from the pump and they are clear. When I give it gas manually it sputters imediately. The one oddity is when I plug into a land line the microwave lights up. When I run the generator it doesn't light up at all.
Customer: replied 2 years ago.
The c is in parenthesis because I can't tell if it's g or c. I think it's g.
Expert:  Hank F. replied 2 years ago.
Ok, your model number, exactly as it is written on the data label, will be 5BGE-FA/26100M.
For the symptoms you are describing, there are 2 common causes.
1. A dead cylinder.
2. A bad carburetor.
The first thing you need to do is to check and make sure both cylinders are firing.
To do this, start the genset. Using insulated tools (or you will get the daylights shocked out of you), remove the front plug wire from the plug. You should hear the engine change pitch.
If nothing happens, that cylinder is probably dead.
If the engine shuts down, the other cylinder is probably dead.
Now put that plug wire back on, and do the same thing to the rear cylinder.
If only 1 cylinder is firing, we need to figure out why.
If both cylinders are firing, then you are going to have a bad carb.
As gas gets old, it turns to varnish and clogs up the passageways inside the carburetor, not allowing enough gas to get to the engine.
This condition is cumulative. Every time gas sits, the varnish builds up just a little more, like coats of paint, until eventually gas can not flow. It will not happen overnight, but the symptoms can show up all of a sudden, even while simply stopping to refill with gas.
The use of fuel additives, such as Sta-Bil or Sea Foam will not stop this process from happening. They will greatly slow it down, but the gas will still go bad.
When this happens, either the engine simply will not start, or it will not run without the choke on (this reduces the amount of air getting pulled into the engine, changing the fuel/air mixture), or it will run but surges.
Another issue that varnish in the carb can cause is that the varnish may not allow the float needle to seal properly against the seat, causing the flow of gas to not shut off when the bowl is full. The result will be gas overflowing the carb and running into the cylinder, and possibly out the air intake. If the gas gets into the cylinder, it will seep past the rings and down into the crankcase. This will be evidenced by your oil level being over-full and/or the oil smelling like gas.
If this is the case, you will need to change the oil and filter, if it has a filter.
The only 2 solutions are to either replace the carburetor or give it a good, thorough cleaning.
When removing the carb, make sure to take a good picture, or make a good drawing of where all springs and linkages are attached. This will make reassembly much easier.
Most people believe that cleaning a carb involves removing the bowl and wiping it out, then spraying some carb cleaner through it.
This is simply insufficient. It takes months or years for this accumulation to build up – it just can not be removed in minutes.
To properly clean the carb, you must remove it, disassemble it (making sure to remove all non-metal parts), and soak it in a commercial solvent for several hours. Soaking it overnight is even better.
Then clean all solvent off with a spray type carb cleaner, making sure to get lots of cleaner into every hole and passage there is. Pay special attention to the tiny holes in the bore of the carb, under the throttle plate for the carbs that have these holes. Use lots of cleaner. And make sure to wear safety goggles to avoid getting the over spray into your eyes. There will be over spray.
Dry the carb with low pressure compressed air.
This is an EPA compliant carburetor, and as such, is not supposed to be taken apart or adjusted.
When you have an issue with it, you are supposed to replace the entire carb.
But, sometimes it is possible to clean them. Just remember, that as an EPA compliant carb, there are no parts available for it, so if you lose or break anything, you will definitely need to get a new one.
Occasionally, even a good cleaning is not going to be sufficient, and you may end up having to replace the carb anyhow. Be prepared for this.
Personally, I do not recommend trying to clean this carb. I recommend replacement.
If for some odd reason this does not help, please let me know so I can assist you further.
If you are getting power to some circuits in the motor home, but not all, then the problem is most likely going to be 1 of 2 things.
1. A tripped circuit breaker on the genset. Make sure both breakers are on.
2. a Loose connection in a junction box, between the genset and the transfer switch.
Customer: replied 2 years ago.
In checking the to see if the cylinder is dead is the red insulation on the wire enough protection from shock to pull the wire or should I use something else? If something else what do you recommend? If a cylinder is dead would the unit run smoothly when not under load? It seems to start and idle fine.It sound like replacing the carb is easier than cleaning it. A tech at Camping World to me they never clean them as it's too tedious and often doesn't work. 1 to 10 what would you say the degree of difficulty on replacing it myself is or a novice? Although I haven't turned many wrenches I can follow instructions well:). Any idea what a new carb costs?
Expert:  Hank F. replied 2 years ago.
I do not trust the insulation on the plug wires. Sometimes it might be ok, sometimes not. I for one don't like getting hit with 30,000 volts. As I stated in my reply, use insualted tools. Rubber handled piers usually work, but they make an actual spark plug wire remover, which is available at any auto parts store for just a few dollars.
Yes, even is 1 cylinder is dead, this engine can run smooth as silk with no load on it. It can run so smooth that even a trained techinican can easily miss it..
As I also stated, I do not recommend trying to clean this carburetor. It is a C.A.R.B. compliant unit, and there are no carburetor parts available for it - not even a bowl gasket.
When bad, this carb is just supposed to be replaced.
The difficulty of changing this carb, on a scale of 1 to 10, I would put at about 6. It is definitely not the easiest carb to change.
This carb will run you $350 - $400. It is not cheap.
Customer: replied 2 years ago.
HI,The time came for me to hit the road, generator working or not. It's not. I'll be back next week and will resume my repair. I'll be in touch then. Thanks.
Expert:  Hank F. replied 2 years ago.