| Re: [GMCnet] Onan (4K) Priming / Fuel Pump Questions... [message #328487 is a reply to message #328486] |
Mon, 22 January 2018 07:40   |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
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Senior Member |
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Steve,
It seem like the origional style pumps developemore once in a while.
On Mon, Jan 22, 2018 at 4:22 AM, Ken Burton wrote:
> SteveW wrote on Sun, 21 January 2018 21:25
>> Greetings from Southern California and THANK YOU in advance for your
> suggestions.
>>
>> My generator (4K) has been difficult to start so I finally jumped into
> it...
>>
>> It seems that the Onan starts quicker when I keep the "prime" circuit
> energized while cranking. Does this sound reasonable ??
>>
>> Holding the prime switch while cranking to keep the pump and ignition
> going during the change over from cranking mode to run mode. This change
>> over is normally caused by the internal alternator starting to generate
> approximately 28-30VAC which tells the board that the engine is running and
>> to keep the pump and ignition going. Mine is slow to come up to voltage
> and holding the prime switch overcomes that delay.
>>
>> On that generator from hell that I worked on last August it had the same
> problem. I had the flywheel off for other reasons so I cleaned all of
>> the alternator pole pieces and and also polished the inside of the
> flywheel where the magnets are. That eliminated this problem. I need to
> do the
>> same to mine but I never seen to get around to doing it. It is much
> easier to just hold the button a few seconds longer when starting. Maybe
> some
>> day I'll fix mine too.
>>
>> From my reading of the various electrical diagrams - it sure looks like
> the fuel pump only runs with the prime circuit energized or from the
>> positive side of the coil while the engine is running. Should the fuel
> pump be pumping while cranking ??
>>
>> No, the pump runs while cranking and while running. The ignition
> coil, fuel pump, and fuel solenoid (if equipped) are all wired together.
>>
>> And... With the priming circuit - shouldn't the pump slow down after the
> carburetor bowl gets filled ?? Is seems that mine continues to pump - no
>> changes in the sound it makes... (it's the "direct replacement pump"
> from Applied.)
>>
>> Yes it should slow down after reaching pressure (around 4 to 6 PSI).
> Several things can cause this. sucking air on the intake side (I doubt
>> this or you would probably have problems running under load). More
> likely is the check valve inside the pump that is not sealing completely
> due to
>> a piece of grit or something. It is very easy to take the pump apart
> and clean / inspect it. If you want a new base gasket and filter are
>> available from NAPA because they sell that same pump under the NAPA
> brand name. I would screw in a tee and small fuel gauge on the output of
> the
>> pump to see if this is what is really happening. A PO installed one
> permanently on mine.
>>
>> Everything seems to work once it's running. No hunting, no stalling,
> 120VAC... Just a little difficult to start.
>>
>> And THANK YOU Gene Fisher. From the 49er blog post on your website - I
> got my Onan electric choke properly wired and working.
>>
>> Steve W
>> 19873 23'
>> Southern California
>
>
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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