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Les854

Generator Will Not Start

13 posts in this topic

I'm onto the next troubleshooting saga. I have the shore power working and most of the accessories are functioning.

When I try and start the generator - Onan 4.8kw - the starter sounds very much like a car does with a low battery. If I am tied to shore and can run AC, etc... voltage should not be the problem, correct? I am such a newbie, should I even try and run the generator while connected to shore power?

Thanks again - I should have this endeavor on Facebook.

Les...

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Les,

No, there is no reason to run the generator while on shore power-- and a couple of good reasons not to.

Now as to your slow turnover of the generator-- just like on a car, sounds like bad voltage to the generator or a bad ground from it back to the battery.

Pull you your digital voltmeter (if you don't have one, get one-- start under $20 at Sears, Radio Shack, etc):

Check voltage between the large positive lug on the generator and any good clean metal part of the generator both static and while cranking. Static-- 12.7 VDC is a fully charged battery, 12.2 VDC is 50% discharged.

Repeat test between the positive lug and a good chassis ground. If voltage better, check ground cable between generator and chassis ground.

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Thanks wolfe,

I was a technician / engineer in a past life. I will do the checks in the A.M. I think I can get to the armature to see if it is able to spin. The real condition of this coach is unknown but I am progressing. Some of the things I am finding are criminal - like replacing a SS pan head screw with a slotted countersunk steel ones. Resolve one issue at a time...

Thanks!

Les...

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It's been a while (was working other issues). I can now turn the generator and it will run consistantly using starter fluid. I pulled the gas line and gas is being pumped to the carb. For some reason it will not run on it's own. Anyone have a clue what to check next? I also had my wife watch the indicator light on the CD palyer while it was running w/ starter fluid - nothing. That would tell me the unit doesn't generate power but doesn't explain it not running.

Thanks for any help,

Les...

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Will they offer troubleshooting advice? The unit is 15 years old and parts are going obsolete.

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How old was the gasoline in the carb when you determined that it would turn over at normal speed (i.e. electrical issue solved), but that it won't stay running without supplemental fuel source?

Wonder if the carb has varnish deposits?

Be very careful running on starting fluid-- hard on the motor and be sure the coach main breaker is OFF, as it would be hard to believe the HZ's or voltage is correct with "supplemental" fuel.

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Les

I remember the private message I sent you corrected the Onan starter just clicking and now I am surprised that no one has mentioned the carburetor fuel inlet through the needle & seat in the float bowl.

Lay rags under the carb and spray carb cleaner on the outside of the carb to try to loosen gaskets for reuse. Remove the fuel hose from the carb.

The main fuel mixture adjustment is in the "bottom" of the hex nut under the carb and must not be moved from its set position at this time. Very carefully remove the hex nut assembly from the bottom of the float bowl under the carburetor and carefully pry the bowl loose while trying to save the gasket. Under the carb touch the fuel float inlet needle valve lightly for movement. Spray carb cleaner into the carb fuel inlet, the underside of the open carb, the float bowl, and the hex nut assembly. Continue spraying until everything looks clean.

Reconnect the fuel hose and hold a container under the carb while pushing the start switch a few seconds to be sure that fuel flows thru the carb.

Reinstall the float bowl with the hex nut assembly. Don't over tighten. Say a prayer and push the start switch.

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Its possible to fix a plugged carb but in our business, Onan service with a level 3 tech, we found it was usually less costly to the customer to just replace the carb with a new one. There are some passages that are impossible to clear and the time spent quite often exceeded a new carb replacement.

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Les,

In your third post you mention having your wife watch for the power to come on from the generator. I don't think you can expect to see power generated right away. Most generators have a delay before the power will kick in. This delay allows the generator to stabilize its RPM so that its power output will be stable. With our generator, an Onan 7.5 KW, the delay is at least one minute before you see gauges indicate electrical output. That would be a long time to run on starter fluid!

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Again, thanks all!

Dwight, I will try and do the cheap fix tomorrow. I do have time and it sounds like it may be the culprit. The first few times I had it fire, I did smell OLD gas. That told me many things may be stuck. I read on another site where this generator needs to generate power to allow it to run so I didn't know where to look.

Tom, thanks for the info. I ran it a few seconds. Never having the benefit of an RV experiance, I had no clue it takes that long to kick in.

This is the good side. With everything I fix, the wife is starting to see the potential. She came home the other day and I was playing the radio (which I fixed), then I slid in a DVD (which I installed) so she could see the TV working. This is a heavy rock but I can see it rolling downhill for a change.

I love this forum - you people are great! If you ever need any advice about a wood fired oven, let me know. :)

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