Small Engine Problems? Ask an Engine Mechanic for Answers ASAP
When the set shuts off, does it just shut off like someone turned off the switch, or does it spit and sputter before it dies?
Will it immediately restart, or does it have to crank extra long before it will restart?
When it first starts, does it sound like it is running at it's normal RPM, or does it seem unusually fast or slow?
Does it run steady, or does it surge (speed up and slow down)?
Have you got a good multimeter to do some testing with?
The set shuts off as if someone turned off the switch.....the governor is wide open when it dies. No extra cranking to restart...but it turns off within seconds on the second try unless you hold the start button down..
When it starts it sounds normal....so it runs steady...no surge....
I have a cheap multimeter...need to upgrade to a digital multimeter.
First off, let's bypass the low oil pressure switch and remote control to rule them out.
Right outside your control box is a black or gray 8-pin connector. The wires will all be marked J2 or P2. This is the remote control. Unplug it.
Remove the control panel.
On the control board, at the 16 pin connector, find the wire marked J1-5. This is the LOP switch. Run a jumper into the back of the plug between J1-5 and J1-11.
See if the set will run now. If so, remove the jumper wire. If this shuts the set off, either the LOP switch is bad, or the engine has low oil pressure.
If it still runs, reconnect the remote. If this shuts it off, there is a short in the remote.
If it still won't run, remove the air filter. While cranking, spray in some gas or carb cleaner. See if you can keep it running for 20-30 seconds this way.
If so, there is still a fuel issue (which is what I suspect).
If this does not help, check the condition of the spark at the plugs. It should be a bright blue spark.
Let me know what you find so far.
The connector for your remote control is not part of the board - it is located outside the control box. Sometimes it is in front and below it, sometimes it is under the control box, and sometimes it is to the right of the control box. The connector is an 8 pin connector, but will not have 8 wires in it. It usually has 5 wires.
The 16 pin connector is the control board connector.
Do not tape down the start switch, and do not hold it for more than about 15 seconds.
It can burn the starter up.
What manual are you using?
Onan RV Genset Service Manual, BGE, NHE, Emerald Plus Series #965-0528 NHE spec E thru K....
Still looking for the remote control connector......
The remote harness will have 4 or 5 wires, probably 5 on yours, that lead away from the set, on the right side.
They go to the remote start switch.
Here is a diagram showing the location.
For you to accept now or wait is entirely up to you.
I do not at all mind if you want to wait. I usually prefer to wait, as you never can tell what may happen.
I assure you, that even if you wish to accept now, you will still be able to respond to this question.
This is your question, and you will always be able to come back to it.
However, if it goes 24 hours without a response, I will be unable to respond until you reopen the question by posting a response.
Since it is raining, maybe you wouldn't mind taking some of ours?
I had to go work on a genset in the rain today.
Okay ..let's wait...
FYI... grounded the wire from the new LOP switch ...there was no difference in response...generator still died after a few minutes.. when I unplugged the new LOP swtich the generator would not start or run...I have not yet run your jumper test...do I still need to?
Removed jets on carburetor to ensure there were no obstructions....took main gas line off of carburetor and replace with a clear line to check fuel flow.... when I cycled the fuel pump the fuel flow appeared to be good but I noticed a small amount of tiny airbubbles ..is this normal?
If you grounded the wire from the LOP, no, you do not need to use the jumper. That's what the jumper would have done, is provide a ground for the LOP.
Technically, no, there should be no air in the fuel line.
But a few tiny bubbles should not hurt.
Go ahead and check the spark and do the spray test.
Okay...so I need to unplug the remote switch and try running generator to see if switch has short..
I will also check the spark at the plug....(although I just put in new plugs) do you want me to check the primary and secondary coils with an Ohm meter?
Why do you want me to do the spray test if I have cleaned the carb?
If the spark is not bright blue, yes, you can check the coil. The primary winding should read 3.7 - 4.5 ohms. The secondary winding should read 17,400 - 19,800 ohms.
On the spray test, I certainly mean no offense, but to most people, 'cleaning the carb' means taking the bowl off and wiping it out. A few of them will go so far as to spray some carb cleaner through the venturi. This is simply insufficient. The internal gas passages in this carb are extremely tiny, and a good soaking it the only way to get them clean - if they can be cleaned. Even a good soaking sometimes will not work, and the carb ends up needing to be replaced.
The symptoms of your set are classic for an electrical breakdown - either in the ignition circuit or in the fuel pump itself.
That's why I always have them do both the spark check and the spray test - to be sure which side it is.
There is also the possibility that the genset is having production issues, but it is extremely uncommon to work for a while and then quit. Typically, if the generator has issues, it will not produce at all.
I did the remote control test....the genset still dies after about 2-3 minutes....and I still have to wait a few minutes before I can restart.....
No offense taken....when I cleaned the carb I removed the jets and cleaned orofices and checked the needle valve for obstructions...put vacumm to the choke and the choke seemed to be operating properly....but when the genset starts shutting down the governor is at full throttle but the engine starts clattering and dies...as if it is starved for fuel. I replace the electric fuel pump as soon as this issue arose....do you reccomend that I bypass the circuit board and hook up the fuel pump directly so that it runs continuously?
What would be the next step on the ignition circuit?
If the governor goes to wide open before the set quits, this is a sure indication that it is starving for fuel.
Yes, I would try to connect the fuel pump directly to 12V to see if this makes a difference.
If this will allow the set to continue running, you are either going to have a bad control board or bad fuel pump relay.
Both are very easy to test.
Let me know how that goes.
Yes, this is very indicative of a bad coil or fuel pump.
You have already proven the fuel pump to be working, so we need to focus on the coil.
Yes, the power must be off.
All wires must be removed from the coil to test it - and it must be hot.
The primary winding is the 2 small posts.
The secondary winding is the spark plug towers.
What I mean by hot is immediately after the engine shuts down.
We know it is working, at least somewhat, when it is cold.
Start the engine and let it run until it shuts down, then immediately test the coil.
As I stated, this is a classic symptom of a coil or fuel pump going bad. It will run for 5-15 minutes when cold, but as soon as it gets hot, it breaks down.
Sure, it's possible that the ignition module is bad - but not very likely. For the most part, they either work or don't.
We have 3 options here causing your shut down:
1. Lack of fuel.
2. Ignition breakdown.
3. Lack of AC output.
We are going to have to figure out which it is.
Since you have installed a new fuel pump, I am leaning on the ignition side.
It's extremely rare for the AC output to work sometimes and not others, and I have never seen it on such a regular basis.
What you need to do now is to monitor all 3 the best you can.
Use an inline spark checker on the plug wire, use a voltmeter tied in to the fuel pump, and the voltmeter to the AC output.
We need to see which one breaks down just before the engine shuts down.
Does it still need to sit for a few minutes before it will start back up?
The positive gets constant 12V from the control board while cranking or running. It should not flicker.
This is a very poor test of the module.
I do not suspect the module at all, but if you wish to test it for piece of mind - here is the best test.
Disconnect the spark plug wires. Disconnect the red and black ignition module wires from the terminals of the coil. Run a 12V jumper to the red wire. Set your meter to VDC and connect the negative lead to a good ground. Connect the positive lead to the black wire coming from the ignition module. Using a 3/8" allen wrench in the rotor through bolt located in the center of the right hand side of the set, slowly turn the engine counter clockwise as viewed from the right end. The meter should read 12V for 1/2 revolution and drop to about 1V for the other half revolution. Turn the motor through at least 3 full revolutions.
This sure is a strange set of symptoms.
Please keep me up to speed with the testing results.
You may have more than one issue going on here.
"AC Output test: Please interpret these results: When generator is running 115 volts steady reading no problem. Then the voltage meter pegs zero (within one second) at the beginning of the engine stall sequence. Conversely if I stop the engine with the stop button the voltage drops slowly to zero as the engine dies."
This is indicating that there is a breakdown in the output side of the system. Very possibly a voltage regulator going bad.
If the set quits producing electricity, it will shut the set down, as some of this electricity feeds the coil and fuel pump.
But the one that is really confusing:
"Ignition module test results- did this test for at least three revolutions and the voltage stayed constant throughout the test, it never dropped below 12V."
This is telling me that the ignition module is not operating properly.
But if it is not, the set should not be running at all.
Please do this check for me and let me know the results.
First, remove the (2) 5/16" screws that secure the ignition module to the top of the generator housing, being very careful not to drop the screws inside. If they fall in, the generator MUST be pulled to remove them. They will do a lot of damage if the set is started with them inside.
There is a trick to getting the module out. The flywheel has fins on it to move cooling air across the generator. One of these fins is shorter than the others. The engine must be rotated so this shorter fin is at the top of the flywheel. Depending on how your set is mounted, it can be very difficult to see down in there, and I often have to use a small flashlight and inspection mirror.
Once this short fin is at the top of the flywheel, the module can be removed. It is a very tight fit, but it will come out. Pay strict attention to how the wires are routed in relation to the module. If the wires are not reinstalled EXACTLY as they are, either the module will not fit when putting it back in, or the wires will be hanging in the way of the flywheel and will get cut.
Once the module is out, simply disconnect the 2 wires from the coil.
After the module is out, we need to inspect the ignition rotor for damage. The rotor is a long piece of plastic that snaps onto the crankshaft, and has a magnet at each end. The magnets are what open and close the contacts in the module.
Looking down into the hole, turn the engine so one of the ‘arms' of the module is straight up. Stick your finger down into the hole, and press sideways (rotational) with about the same amount of pressure you would need to slide an empty coffee cup across a table. Turn the engine 180 degrees and test the other arm in the same manner.
The arms should not move. If they do, the rotor is cracked and must be replaced.
If the rotor is OK, just change the ignition module.
Here is a drawing to help explain the relationship between the module, rotor and crankshaft.
The diode test on the VR is not always accurate. Sometimes the VR must have a load on it to show a failure.
Let me know about the ignition rotor.
Also, when you tested the ignition module, you did have the wires disconnected from the coil, correct?
Sorry this took so long, but perseverance does pay off.
Sometimes it just takes a while to find the problem.
I wish you had let me know you were going to replace the VR - I could have directed you to a cheaper source than Onan.