Replacing the Generator Fuel Pump

The long saga with my generator refusing to run longer than a few minutes is finally resolved. 

How the generator got in this condition is worth reviewing.

Since we have owned our LD, we have been on the road over half of each year so the generator was used as we eschew campgrounds with hookups. However, camping wo popcorn is way too primitive. [It’s not the hookups, we mind, it’s that the people that frequent these CG’s are just not “our people”. We have little in common with them. Concrete Campers and Boondockers are two different species]

At home, I run the generator with a load for 45-60 minutes a month.
Using the generator, keeps the gasoline in the carburetor from turning to varnish and gumming it up.
A health issue prevented me from doing the monthly exercise for well over six months.
In hindsight, had I thought about it I could have drained the carburetor. But that bypasses the other reason for exercising the generator.

Not using the generator is true for most LD’s. I suspect few do a monthly exercise. (*) So there should be a lot of gummed up carbs out there. Mine sure was after months without use.


Symtoms:
It would run for 3-4 minutes, constantly surging. I could see the butterfly valves rapidly swinging back and forth. It would throw a 3-3 code which is not a documented code.

Trying to figure out the problem, I entertained all sorts of suggested remedies. Few had any bearing on the issue. One was too drain some oil out of the crankcase. Really! I noted the fuel pump supplied seemingly copious quantities of gas. After cleaning the carb bowl of varnish (https://www.youtube.com/watch?v=6053Qti0OLU&t=1102s) it ran a few minutes longer. I finally bit the bullet and ordered a Onan (not a knock off) fuel filter and pump. ($200+) I then embarked on the extremely PIA procedure to replace them. (https://www.youtube.com/watch?v=jlrHl0OWSZU)

Worth doing:
1)  Put colored tape on the wires you disconnect so you know where they go.
2) Take pictures before you take it apart.
3) Try see where the wires will have to be tucked back in as you carefully and slowly remove the control board. I failed this.

When I got it put back together, I primed it and it fired up and ran perfectly. Bob’s your uncle.

Be sure and tighten the fuel supply line from the pump before replacing the control board. I failed this and got to remove the board to access the fuel line. Also check for any other fuel leaks.



* If you see an aged RV advertised with low hours on the generator, figure it does not work. A 10 year old LD, should show 120 hours minimum on the meter.

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Generator Fuel Pump

If you remove the generator access door and look at the carburetor, towards the bottom is a largish head screw. This is the carb bowl drain. Draining the carb bowl during storage goes a long way in keeping the gen-set happy. When loosening or removing the screw, a little gas will drip down - just put a small bowl or paper towels down to catch it.

With the gen set prime/start switch right there on the unit, you can push the prime button and instantly see if the bowl is filling up again. Without taking anything else apart, this will be an aid in troubleshooting. You can hear the pump working, but if there's no gas entering the bowl, the first thing to check is the main fuel tank level. Is it above quarter full? Next would be the fuel shut-off solenoid at the bottom of the carburetor bowl. The solenoid has two wires going to it, ground and positive. You'll need to remove the wires to unscrew the solenoid. The ground wire is fixed to the gen frame right in front of you. The hot wire has a spade connector that will be revealed by pulling it towards you. It is easily cleaned of gunk and put back in service - no parts needed. Last reason for no gas would be a break in the fuel line from the truck gas supply.

When I did mine, I removed the whole carb to get at everything, as I didn't know it was just the solenoid causing the no run problem.  The carb bowl can be removed without removing the carb itself. Take care to note where all the washers are located.

Edit DHM There is probably a just right wrench for removing the carb bowl. I had to use plumbers pliers.

If you get in the habit of draining the bowl before long storage, a gunked up fuel solenoid should not be of concern.

BTW - The reason for the recommended monthly gen set run is threefold. To heat up and dry the generator windings, to exercise the motor, and importantly to re-magnetize the generator's stator core. It is the residual magnetism in the core that allows the gen to start making electricity. If left too long without running, one may need to "flash the windings" to get the generator to function again. (Doable with the "flashing coil with two drill motors" trick (search Youtube using that term for instructions).

bumper

Generator - Replacing Onan 4000 Microquiet Fuel Pump and Fuel Filter

If the generator stopped with a fault code of 36 points that points toward a problem with the fuel supply. But is it the fuel filter, the pump, or the fuel line or a clogged fuel cut off solenoid?


Safety:
Be safe when doing this. Think about what could go wrong and plan accordingly. When working on the wiring be sure the battery power is OFF or DISCONNECTED.  Good time to use your battery disconnect switch if so equipped. When working with the fuel lines be sure to have a fire extinguisher handy. When reconnecting power on the other side of the RV have a spotter in front of the generator looking for smoke. The job is easy but there are a lot of steps. Not paying attention will bite you and could bite hard.


Required Tools:
Camera (cell phone works fine)
Small ratchet (3/8th or 1/4)    
Short extension (a second short “wobbler extension” will make the job easier)
Socket set open (a deep well 1/2” socket would be nice but not required)
Open end wrench set
T30 Torx driver that can be used on a ratchet
Vice grip, plug or some clamp to stop fuel flow in the fuel line    
Plastic fuel tank (or what you own as long as it fits under the RV)


The second and third characters of Model No, KY in the picture and the last character in the model number, K in the picture, are used to determine what Onan pump, filters and spark plug are needed. Make a note in your manual what number you have.

Parts needed:

Onan Fuel Pump - Airtex E11007
Onan Fuel Filter

Onan Air Filter
24 inches of fuel line 1/4 inch inside diameter (ID)
Teflon plumbers tape
Fuel hose clamps,

Testing the Fuel Line
Some Lazy Daze RVs have had a fuel line issue. These seem to be from the late 1990s to the early 2000s. With this in mind, it is a good idea to conduct a simple test. 

Start by getting the passenger side up in the air so you will have room below the coach-box to work. Six inches is good.


1. Go to the generator compartment and remove the cover for the generator. To determine which side the fuel line is most likely located look for the starter solenoid and air filter. In the picture, the air filter is labeled and the starter solenoid is the rusty item below and to the left of the air filter. The fuel line will be on the underside of the RV. It will run up against the exterior of the Onan generator housing outside of the area where these two items are located.

2. Where the fuel line meets the generator you will see the clamp holding the fuel line to a barbed connector. 

Clamp the factory fuel line a few inches upstream of this point to stem the fuel flow. Note, unless the fuel filter has been replaced at some point, the hose clamp will not be the same as pictured. It will be a compression clamp common. That type of clamp cannot be reused. The shiny object the fuel line is connected to is the new Onan fuel filter. (Off topic: The fuel filter alone can be replaced or just tightened by removing the hose from this location.)
 
3. On this step MAKE SURE YOUR EYES are NOT UNDER the connection to the fuel filter. Some fuel is going to leak out and you do not want it on your face. Once the fuel line is securely clapped disconnect the fuel line fuel line. I had to cut the line off the old fuel filter. There was enough line to reconnect. But only just enough. Plug the fuel line and make sure the gas is not leaking from the line.
 
4. Attach the 1/4 inch fuel line you purchased to the fuel filter. Place the other end of the fuel line in the Gas can.
 
5. Prime and start the generator. Make sure there are no gas leaks at the new fuel line connection.
 
6. If the generator runs for a longer period of time than it does on the main fuel tank, the RVs fuel line between the generator and fuel tank is suspect.

If the generator stalls as before while running on the external fuel source there is an issue with the fuel pump, fuel filter or carburetor.
 
7. Secure the external fuel tank from testing. 

Replacing the fuel filter:

1. Remove the negative cables from the 12-volt coch batteries. Or use the battery disconnect switch if so equipped. It is a good idea to take a picture before removing the cables to help with replacing them. 

2. Go to the area that holds the starter solenoid and air filter. The wiring harness, starter solenoid, and air filter will have to be removed.

3. Pull the harness gently to bring the weatherproof connector out. 

Gently lift on three tabs to pull the connector apart. If you have not encountered this type of connector there is one on each shoulder and one across the middle. Gently pull these away from the keeper then pull the male section from the female section.

4. Remove the starter solenoid. Be sure to take pictures of which wires are on which post, even better tag them. 

Once the wires are off, replace the washers and nuts so they don't get lost.

5. I could not get a good picture of the inside post while at step 5. So the picture of the other post was taken after the solenoid was removed. The solenoid is held in place with one T30 Torx bolt (not shown) and a locating tab. Note that in the picture the solenoid is upside down so what was the far side post in step 5 is now facing the camera. I should have cleared the loose wire out of the picture. There is only one wire connected to this post. Not two.


6. Generator with harness and solenoid removed:

7. The fuel pump is below the “brain” box. The box is held in place by two T30 Torx bolts. These bolts are accessed from outside the generator housing but inside the Lazy Daze hatch. This is where the wobble head extension is very useful. Also, the bolts on this RV were slightly rusted. I needed a ratchet to break the bolt loose. Once the two T30s are removed the brain box is free. To remove it from the compartment I had to remove the air filter, then shimmy it out, Start by pulling the wires out of the way and then lifting the box on the left side There is a wiring harness on the bottom side of the brain box to be removed.

Finally, the fuel pump revealed! Note the single-use ear clamp. That may be a problem to remove. I used an abrasive wheel on a Dremel. Yeah, sparks and gas, but it was drained. The hose must be removed so the pump can be removed. The fuel filter is behind the pump. It is easier to remove the fuel line from the filter than to try to rethread the filter into the pump. That is a major PIA due to the angle.

After removing the line from the pump I disconnected the other end from the carb and pulled it out. I will replace with a new line.

When you get the pump out you may wonder how only one bolt was holding it in place. If you look carefully, you will see a slot on the right/forward side that the right foot of the pump slips into. Remember this when the time for reassembly comes.

8. With the control box removed locate the ground on the front left wall of the generator box under the tangle of wires. [Right behind the Caution label] There are several wires led to the ground on the inside of the box, plus the cable on the outside of the box that leads to the chassis. The ground wire for the pump is in that rat's nest.

You will need a 7/16 socket on an extension and a 1/2 box or open wrench for the nuts on the exterior of the box. There are two nuts. One holds the chassis ground and the other allows a tight clamp on all the wires on the inside of the box. When putting it back together think of the ground problems that can come from not well tightening this ground. 

With the ground bolt removed you can take off the black lead from the pump and trace the red one to its plug connector. 


Outside the housing attached to the bolt is a lock washer and nut, then a ground wire back into the chassis and another lock washer and nut. Note that the ground wire is not double nutted in place. Each nut has a job. The first to secure ground inside the housing, the second to secure the ground wire to the chassis ground. DO NOT CHANGE this.

Check again for leaks. Then restart and run for twice as long as what the time was for the RV to shut down when it had a problem. For the first 10 minutes stay near the pump and connections looking for any sign of a gasoline leak.

1. Reassemble the ground.
2. Reinstall the brain box. Use a nail or drift once one hole is somewhat lined up to keep it in place then line up the second hole and loosely put in the first T30 then the second. Once both are threaded in place tighten.
3. Replace solenoid (pay attention to wires).
4. Replace air filter.
5. Plug harness back together.
6. Hook up fuel line.
7. Hook up battery.
8. Disconnect spark plug wire from the plug
9. Prime fuel pump.
10. Look for fuel leaks at fuel line and fuel pump. It will be hard to see the pump/filter but you should be sniff for the odor of gas.
11. If no fuel leaks reconnect spark plug and start generator the local (outside) switch.

12. Run just a few minutes checking for leaks. Stop generator and let sit for 15 minutes.

13. Check again for leaks. Then restart and run for twice as long as what the time was for the generator to shut down when it had a problem. For the first ten minutes stay near the pump and connections while looking for any sign of a gasoline leak.
14. Go inside the RV. Stop the generator then restart to make sure the remote (internal) starter button works. While the generator is running place the generator under load by running the AC for a while. While everything is running go outside and, you guessed it, CHECK FOR Gas leaks.
25. Shut down. Check once more for gas leaks after everything has cooled. You should be good to go.
26. The author might have been a little paranoid about gas leaks so check the next few times you run the generator.

Other Stuff:

A flexible or wobble extension allows the socket to wobble on the nut, allowing the ratchet to be a few degrees off perpendicular.

Contributor: John DaCrema
     
Updated: 5 November 2018

Adding A Primer Circuit To Older Generators

Many RV builders added the primer circuit before Onan actually added
it from what I can determine. It is a function that can be installed on any
vintage Onan with an electric fuel pump. II have had it on every RV
equipped with an Onan from 1983 models through my Class A that was a 2004.
An internet search turns up several hand drawn circuits for adding
the function and the same questions that have been asked here have been
asked several times before on other sites with no one well defined answer.

So it seems as if Onan decided it was a good idea at some point.
Individuals and RV builders were adding it in a couple of ways before this.
Some of the circuits consisted of adding a momentary push button to the
fuel pump often drilling a hole in the Remote switch panel to add this.
Here is one article about it The section labeled 15 shows how it was added.
Could be added to those that don't have it now probably.
http://www.gmcws.org/Tech/dsimmons/onan/onan.html

Garry

Generators – Trouble Shooting

It's easy to take your generator for granted - all you have to do is push a button and presto, you have 110 V AC power. But then once in a while, it's not quite so "presto". You push the button and you're not rewarded by the sound of the genset operating.
The first thing to remember is that generators do better when used more often. It is highly recommended that you "exercise" the genset at least once a month for an hour under at least half load. This helps prevent the carburetor from getting gummed up.
There are two sections in this article - The generator will not start and the generator starts, but produces no power.

Generator Will Not Start

Starting in 2002, the Onan MicroQuiet replaced the Onan Emerald Plus. The Microquiet has a prime function on the Start/Stop switch on the range hood. This feature was not documented in the LD Owner’s Manual until 2007.
1. Before starting, hold the switch in the STOP (down) position until the green light comes on. You may hear a faint rattling noise as the fuel pump pulls gasoline from the tank.
2. Release the button when the green light comes on, and press and hold the switch in the START (up) position until the generator catches, then release it.

If the button is pushed and there's no cranking or starting noises - - suspect a dead battery or loose/corroded connections.
If the button is pushed and there's only a clicking noise - - low battery, loose connections, or faulty starter solenoid (relay or contactor - same thing).
If the button is pushed and the engine cranks normally but doesn't start - - low or no fuel reaching the engine, faulty ignition system, low oil cut-off, gummed up carb, etc.
If it has a little vibration or hesitation: Try cleaning the spark arrestor. This is a plug that is in the muffler-like exhaust under the units, Its not the regular muffler but one that is under the unit. Some have one plug some have two. Unscrew the plug and start the unit, let it run for 15 minutes, shut off and re-install the plug.
The plug may be difficult to remove. Heating it should help break it loose. If you want to try penetrating oil, PB blaster is highly recommended; it's a penetrating catalyst and a magnetic lubricant.
Refer to the Onan Owner's Manual for deciphering the trouble codes that the generator displays.
Try the start switch on the front of the generator - if it starts there, the start switch/wiring is the culprit. If it does not then the battery feed to it could be one issue. Can you measure 12 volts at the gen from the line(s) that comes to the battery? It is a large wire that comes up from the lower right corner of the gen box. Connects to a large stud on the start panel.
Check the circuit breakers. They are self resetting but can go bad. You can check to see if they have 12 volts on each side of the lugs. I think LD runs 2 lines over the gen to get the right staring current applied the gen. If you only get 12v on one side of the switch (s) then the switch(s) is bad. If you don't measure 12volts on each side of the switch, then the line(s) between there and the battery need to be looked into. They should be connected to the battery.
Are your house batteries fully charged? Are the battery connections clean and tight?
There is a small possibility you have lost ground to the gen box or the gen itself. There is a braided ground strap near the base-plate mid gen. You would probably have to take the gen out to get a good look at it on yours. You could always check continuity from a bolt on the gen case to the mounting plate to see if the ground strap still works.
Contributors: bumper, oldtrucker63, Ramon
Revised 1 Jul 11

Generator Starts, but no Power

Generators are wonderful things to have sometimes.....when they work. In a previous LDC article we discussed generators that won't start. We go a step further in this article and present some trouble-shooting tips for a generator that starts and runs, but is not putting out any electric power.
- Check all the electrical breakers. Not only are there breakers inside the front cover to the converter/charger, there is also a breaker located on the generator. Turn it all the way off and then back on. If the microwave and/or AC were turned on when you started the generator, the load may have been too much and tripped that breaker. It's better to ensure all power-hungry appliances are turned off before starting the generator.
- There is an Automatic Transfer Switch that switches the rig's 120V source between generator and CG power. Verify that yours is working.
- Do you have a "whole house" surge protector? There is usually a delay of a couple of minutes before it will allow power through it.
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More:

First, make sure that the switch on the side of the generator has not opened. Your manual will show you where it is. Assuming that the switch is closed, the next question is what is the status of the breakers in your service panel. Try to reset the main breaker. Still no power? If not, (and this was my issue, solved with Andy's help) you may have a bad Automatic Transfer Switch. The ATS is located behind, and attached to, the main breaker box. Replacement can be a real headache, but that is the only way to deal with a bad ATS.
Unless you are pretty comfortable working on equipment, including 110v power systems, replacement is best done by a service person. Assuming you are comfortable here are the steps:
1) Remove the front of the service panel and cut all power - shore, solar, and batteries.
2) Using a multimeter, verify that everything in the panel is dead - no voltage anywhere.
3) Unscrew the four screws that hold the panel in place and slide it out until you can see the back.
4) The metal box on the back is the ATS. On the very back near the bottom of the ATS is a screw. Remove that screw.
5) The back and top of the ATS will now slide up, exposing the ATS connections.
CAUTION - steps 6 to 10 involve checking voltages on live, exposed circuits. DO NOT TRY THIS UNLESS YOU KNOW WHAT YOU ARE DOING!!!
6) Turn on the generator.
7) Screws 1 and 6 are for the power from the ATS to the panel. Screws 2 and 5 are from the generator to the ATS. Screws 3 and 4 are from shore power to the ATS. Check voltage between 2 and 5.
8) If there is no voltage, or if significantly other than 110v, you have either a generator problem or a wiring problem from the generator to the ATS.
9) If there is 110v between 2 and 5, check the voltage between 1 and 6. If you read no voltage you have a bad ATS.
10) Turn off the generator and put everything back together.
11) If the ATS is bad, order a new one and install it when it arrives.
12) If the ATS is not the problem, and your generator is not delivering voltage to the ATS, and the breaker switch on the generator is closed, you need a generator service person.
Contributors: Alex Rutchka, Doc, JC, Ken F