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Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 14889
Experience:  Certified on Onan and Generac generators
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Onan 7000 quit running after about 30 minutes and will not

Customer Question

Onan 7000 quit running after about 30 minutes and will not crank again. There is a gas leak at filter. Replaced fuel filter and stopped leak but still will not run. Checked oil level and it is good. Any help would be appreciated.
Submitted: 2 years ago.
Category: Small Engine
Customer: replied 2 years ago.
I am getting a code 36 on generator. The rv is full of gas and fuel runs out of the gas line when I take it lose. I can push the primer button and hear the pump running.
Customer: replied 2 years ago.
(Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Hank F. replied 2 years ago.
My name is ***** ***** I am going to assist you with this.
When you press the start button, do you hear anything at all? Does the fuel pump come on then? Do you hear the starter solenoid at all? Or does it do nothing when you press the start button?
Customer: replied 2 years ago.
It turns over and tries to start. Occasionally it will chug a couple of times then gives the 36 code. I can here the fuel pump on primer.
Expert:  Hank F. replied 2 years ago.
Ok, so the engine is cranking - it is just not starting. There is a huge difference there.
Lets start with testing the fuel pump.
First, make sure you have at least 1/4 tank of fuel. Anything less, and the genset will not run.
To do the test, remove the fuel line from the carburetor. It will be necessary to cut the crimp-type hose clamp.
Place the fuel line in and empty container.
Press and hold the 'STOP/PRIME' button for about 10 seconds.
When you first press the button, there will be a 3 second delay before the fuel pump activates.
When the fuel pump does activate, it should make a faint 'humming' sound. It should not make a loud 'clacking' sound. A loud 'clacking' sound indicates that there is air in the pump, and can indicate either a faulty pump, or no/not enough fuel getting to the pump.
There should be an immediate strong, steady flow of fuel in a pulsing flow.
If there is no fuel flow, or if the flow seems very weak and thready, locate the fuel supply line.
The fuel line attaches to the fuel filter, and the fuel filter is screwed directly into the pump, which is located underneath the front left corner of the genset.
Remove the supply line from the filter, and attach a length of fuel hose to the filter.
Place the end of the hose into a gas can.
Now press and hold the 'STOP/PRIME' button again, for about 10 seconds.
If you still do not get sufficient fuel flow, the pump is bad and needs to be replaced.
If you now get good fuel flow, but did not on the first test, either your coach is low on gas (there must be at least 1/4 tank for the set to run), or the fuel lines between the tank and genset are bad.
If the fuel pump is working, your problem will be a bad carburetor.
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.
Expert:  Hank F. replied 2 years ago.
Did you find the problem yet?
Customer: replied 2 years ago.
It is pretty obvious you didn't completely read my post where I told you what all I had already checked. It was waste of $27.00 and it took to long for you to respond. I said I needed an immediate response because I was headed on a 4000 mile trip. I took it to an Onan mechanic and he found the problem. $150.00 to get it repaired. I will not use this service again.
Expert:  Hank F. replied 2 years ago.
We are not machines, and can not be online 24/7. Some of use work regular jobs, and help on Just Answer on the side.
I took your question as soon as I saw it. I can't answer for someone else as to why they did not take your question.
I did read your post. The only things you mentioned trying was to change the fuel filter and check the oil. I asked you to check neither one of those. The first thing I asked you to check was to see if the pump was pumping fuel. I even also explained that if the pump was working, the next most likely problem was in the carb.
You never replied back to me until 5 days later. So please do not sit there and try to say that I was the one taking my time.