Question about Watts Onan Portable Generator - 4000 , Model# 5500

3 Answers

I actually have a Onan Microquiet 4000. I prime it, and can hear the fuel pump pumping. It starts, and runs 5-10 minutes, surges a little, and then shuts down. It will not start after that. When trying to prime again all I hear is a click, nothing else happening. Took the fuel line off, and tried cranking it, and no gas comes out. Don't know if it is a fuel pump problem, relay problem or what. Don't know how to get to the fuel pump. Don't have the repair manual. Any suggestions?

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  • country11781 Aug 27, 2010

    I have the model number, it is #4kyfa26100k. any tips on accessing the fuel pump, and associated wiring? I can't even see it. Thank you

    This unit is in a toyhauler, and not motor home just for information.

  • country11781 Aug 28, 2010

    Thank you, first of all when I first try to start it, I hold the primer in for a while, and I can hear the pump running. It will then start, and run very good for 5-10 minutes. It will then start to surge, and then stall.

    If I try to start it again, it will not start. If I try to prime it again I hear a click, but not the pump running. If I take the gas line off, and try to start it, no gas comes out. It really acts like it runs out of gas. If I wait long enough I can prime it again, and hear the pump run again, and it will start, and run again for 5-10 minutes, and shut down again. The oil level is good, air filter is clean, and I believe the code I got last I checked it was a 36 or something like that, and the book points to a fuel problem. I do not have a repair manual, and don't know how to get at the fuel pump to check the voltage on it, or the relay.



    Thanks again

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This is from the manual so read first:

Normal Starting Sequence
This is what normally happens when you start your genset. Pressing and holding the start switch causes the control board to send 12 volts to the ignition, fuel pump, choke heater, start solenoid and field flash circuits. The engine then cranks and starts. Oil pressure and generator voltage build up within 1-2 seconds. This causes the control board to keep sending 12 volts to the ignition, fuel pump and choke heater while cutting off 12 volts to the starter solenoid and field flash circuits. The start switch can then be released and the engine keeps running. Some models differ slightly in operation. On models equipped with magneto ignition (KV, Spec. C-F; KY, Spec. A-E), the control board un-grounds the magneto kill circuit. Model KY, Spec. B-E uses a fuel solenoid in addition to the fuel pump. Models fueled by LP gas use a fuel shutoff solenoid valve instead of a fuel pump. Several conditions can prevent the engine from starting/running and are covered under Troubleshooting.

This is about the fuel system:

CHECK FUEL SYSTEM If the engine cranks and has spark but does not start, the problem is likely fuel related. This can be confirmed by injecting a small amount of starting fluid into the air intake. If the engine fires and tries to run, it is starving for fuel. Listen for the fuel pump running during cranking. Check for 12 volts at the FUEL PUMP pin on the control board during cranking. If there is no voltage, the control board is defective. The pressure and flow of the fuel pump (and fuel filter) can be checked by temporarily disconnecting the fuel line to the carburetor and jumpering the FUEL PUMP pin on the control plug to battery positive. Take adequate precautions when handling fuel. If pressure and flow are normal, reconnect fuel line. Note: If the generator has not been run for several months, the carburetor float may be stuck closed and /or the jets and needle valves may be gummed up by old fuel that has turned to varnish. These conditions interfere with normal fuel delivery. The automatic choke may be stuck closed or binding so that it does not open as the choke heater warms up. On Models BGM and NHM spec. B and later, make sure that the electronic governor goes to full throttle one second after cranking begins. Any of these conditions will prevent the engine from starting or running smoothly and must be corrected before proceeding.

Follow the fuel line from the cab back to the fuel tank. The first connection before the carb is the fuel pump. It should be round with 3 electical pins.

I think you have a fault induced fuel shut off issue. This can be due to low oil pressure. Check the oil level and make sure that is serviced completely and try another start.

Follow the fuel line back to the fuel shut off just off the bottom of the fuel tank. Knowing full well you can have a fuel mess be prepaired for a fuel mess and remove the fuel line just off the bottom of the tank. You should have fuel flow. If not then there is either a problem with the fuel shut off or the fuel tank outlet in the bottom of the tank has debris covering the hole.

If the problem persists respond here and someone will help you.

Thanks for choosing FixYa.

Kelly

Posted on Aug 28, 2010

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Hello. If you are pressing the start button and the genset is turning over, but won't start, then this could mean several things. First, your fuel pump could be bad. Second, Ingnition coil is bad. Third, faulty spark plugs, or carberator is gunked up. Also, check compression. Should be over 110 psi.

That said, you could get a can of starter fluid and give the air intake a couple of squirts then start it up. Keep it running by continuing to spray the starter fluid for up to a minute to clear out any gunk in the carburator and within the engine. J.

Posted on Aug 28, 2010

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Hello,

It does sound like your fuel pump is having issues, or the relay that controls the pump is the culprit.

If you have one, put a multimeter across the fuel pump wires. Start the generator, you should have 12volts when trying to start, as well as when the generator is running. If you dont, then you are looking at a control relay failure. If you do have the 12volts, wait for the generator to start surging, and monitor the voltage. If it stays at 12, then you are looking at a failed pump.

If you post the Onan Model / Spec / Serial number, I may be able to find a service manual for you.

Posted on Aug 27, 2010

  • Sheldon Dedek Aug 28, 2010

    No luck on the service manual.

    When the generator shuts down, the light on the switch should start flashing a code, could be 2 or three digits. First digit will be the number of flashes, then there will be pause, second digit will be flashed, paused, then third digit (for a 3 digit code).

    Some codes that I am anticipating is 14, 15, or 36. Start the generator, let it run until it has its issue and dies, then look for the code on either the remote switch (if equipped) or local switch (on generator control panel).

  • Sheldon Dedek Aug 28, 2010

    The fuel pump, if memory serves, is located on the left side of the generator, as you are facing the control panel. In order to get to it, you will have to pull the generator out of the trailer, so that you are able to remove the cowling / cover.

    Your fuel pump is failing due to thermal. The click that you are hearing is the K1 relay engaging, of course, the contacts could be burnt on it. I would suspect though, if the contacts were burnt, that it would not be able to support the fuel pump load at all.

    The relay is located on the control board, which is located on the housing that the local switch is mounted upon. But, I don't think that the relay or control board is going to be the problem.

    Oh, and 36 is a Stop Without Command error. Basically, the engine stopped without being told to. The most common code for an unexplicable shutdown is 14 (frequency too high), and 15 (frequency too low - common to overloads).

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Posted on Jan 02, 2017

  • 6 Answers

SOURCE: Onan MicroQuiet 4000 Generator

Remove the air cleaner and inside near the throat of the carb is two bolts holding the carb to the intake remove these. Unhook the fuel line and twist the carb to allow the linkages to remove.

Posted on Sep 28, 2009

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