20 Most Recent Watts Onan Portable Generator - 4000 , Model# 5500 - Page 6 Questions & Answers

Check the spark plug and the ignition coil for good sparking.

Get the spark plug out, or with another spark plug connected to high voltage cable, outside the motor, the outer part of the plug connected to motor ground and see if spark is present at cranking.

Try dinosaur electronics for a cheaper board,
http://www.dinosaurelectronics.com/Onan_boards.htm

Check the luboil level or sensor if level is normal.

Is there voltage on generator terminals. If not you must recharge the field or check the Voltage Regulator output

Try to reset the AC breaker. If no success the field needs to be recharged.

In what position is the switch under the voltmeter and does it read some voltage, may be very low? 
Is the main switch in run position?
Is there a charged battery connected to it?

Do you have reading on the voltmeter. See the position of the switch under it. Try to reset the lights and the sockets.

The switch should be three positional.
The upper position is only for starting. Continuous running is in the middle (self holding) position. Lower position is to stop the generator.
If left in middle position it is not running you may have the switch bad, or the generator is stopped by low oil level.

please visit http://www.optigenerators.com/PartStore.aspx and check it up what fuel pump you need.

The brushes need to be filed smooth or replaced. 15 minute job, remove 2 bolts on the generator cover ( side opposite the pull start ). Remove 2 more bolts holding a black plastic thing about 4 inches long on the left. Behing that piece, there is 1 bolt holding in the brushes ( red and white wire attached ). Remove the brushes and if they're not smooth, file down and reconnect everything. I was done in 15 minutes in the middle of Maine woods thanks to my Leatherman.

voltage regulator is causing surge make sure its not overheating is a heat shield missing.

Your solenoid might be bad or your starter motor might need new carbon brushes. If you can take out the starter motor and see if you can manually rotate it, if it is not to hard to turn it, if hard to turn manually your starter might have something bad inside. A bad bearing or bushing. One more thing try this while cranking try to tap the starter motor.

Check the gas cap. There is a vent to allow air into the fuel tank as the fuel is drawn out. If this vent becomes clogged, a vacuum can be formed in the tank. This can prevent gas from flowing to the carburetor.

Listen carefully when you remove the cap. If you hear a "whoosh," there likely was a vacuum.

Possible low oil / low oil switch

Governor is out of adjustment

Altitude settings are incorrect

Idle control circuit

5-30, 10-30, 10-40, 15-40 depending on your operating temps

10- 30 will work just fine in most temps

Hi and welcome to FixYa.

Sometimes out of the blue these things just up and throw a fit. If you were trying to start it and it backfired back through the carb then one of the valves may be stuck in the open position. (Even happened on my own generator 2 times)

Note you will have to change the oil if you do step 1.

Step 1

Ignition switch OFF

REMOVE SPARK PLUG

I have found that if you take a flashlight and make sure the piston is all the way to the top.
Then fill the head with gas first all the way up to the top of the spark plug hole and then every once in a while add a little more gas that what ever GUNK there is around the valves will dissolve. (you can use brake fluid also... just harder to clean up and not so easy on the paint.)
Keep adding gas.... as needed for about 30 mins.

Step 2

(remember piston is STILL at the top of the block)

Remove the valve cover (Careful so as not to tear the gasket) and check that both rocker arms can be moved just a bit. If there is no movement up and down (.005 - .007) then you have a stuck / sticking valve that is not traveling al the way to the valve seat inside the head.

Put some oil on the valve stems and let it drip onto the stem seal area where it goes into the head.

(Note this next procedure makes the gas come out the spark plug hole)

Rotate the engine slowly for several turns and then place the piston all the way to the top again.

Check for clearance again of .005 - .007 were the rocker arm depresses the vavle. (You really don't need a feeler gage just must have slight movement)

If you have the clearance... then do what you can by spinning the engine ignition off to get rid of the excess gas in the cylinder and clean up the mess. Make sure that if you start the unit it will not catch fire.

Install spark plug.

Ignition on

Attempt normal start.

NO START? see below

If no start do a comression test with your THUMB over the spark plug hole. If the hole is too deep sacrifice a paint brush handle (cutit off and form fit it and so that it mates in the hole no deeper than 1/2 inch / length of spark plug. It should really give you a good stong puff of air against your thumb of flat out shoot the paint brush handle out of the spark plug hole a fair distance. If it does not do this then your going to have to remove the head and hand lap the valves with grinding compound. I love OHV heads.... they come right off after you get all the rest of the **** out of the way.... !

Let me know what happens.

Thanks for using FixYa!

Kelly

1 Check the oil..... i.e full

Unhook one of the wires on the oil sensor and see if you NOW have spark.

I don't know why a lawn mower shop could not fix your generator. I certainly fixed my share of them during my lawnmower repair shop days.

Half of the problems I ever saw with generators is that they for a number of reasons would not start.

Thanks for using FixYa!

Kelly

recheck, reclean,and rebuild carb possible had moisture in fuel and carb --white smoke--but sounds like float and carb still gummed up

Hi,
This sounds like a problem with fuel settings or dirt in the jet.
If you can find the carb adjustment screws, with it runing on full choke - screw it in fully untill it stalls, then back out to original position, then restart.
Take off choke and adjust setting untill it runs well when warm with choke fully out.
You can then try and make it run leaner without stalling.

Yes it wil not let you run your motorhome out of fuel they set it up that way so you dont strand yourself you may have a air bubble in the fuel line to the generator try blowing air generator fule line back into the tank