644 & 646 disapointing results

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Eugen Canada
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Re: 644 & 646 disapointing results

Post by Eugen »

Harry wrote: Thu Jun 23, 2022 10:27 am I eliminated the electric fuel pump then checked it again wiring it directly to battery. No pumping and was going to put on a mechaical Onan pump which is powered by the cam from a donor engine. I replace the diaphram on it mounted it on the engine and could not get a drop out of the pump, even after priming it. So now it's unto plan C which is what Boomer mentioned last week during a phone conversation. Pulse pump which many small engines have today. He mentioned I could connected the vaccum side of the pulse pump up to the dipstick tube. I was thinking maybe I could attach it to the breather which is in close proximity to the carb. Anyone have any other ideas out there?

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Harry
@Harry why not get the proper mechanical pump for the Kohler K321? That worked on the original engine for many years, and with a new one it should work for many more years. Or you are talking about the 646 here? I might have gotten confused.



Edit: never mind, I went back and read the thread, you were talking about the 646. I do not have any ideas about that, sorry. :(
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Harry United States of America
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Re: 644 & 646 disapointing results

Post by Harry »

Yes Eugen, this is an Onan CCK engine. The mechanical fuel pump is similiar but slightly different than the Kohler 321 pump. I was thining of rebuilding the Onan mechaical and try to get a kit from Boomer, but he said try a pulse pump instead. I'll have in tomorrow and was just reaching out for ideas where to plumb it to.

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Harry
1973 444, 1974 644, 1976 446, 1977 646, 1986 226
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Re: 644 & 646 disapointing results

Post by DavidBarkey »

Harry wrote: Thu Jun 23, 2022 10:27 am I eliminated the electric fuel pump then checked it again wiring it directly to battery. No pumping and was going to put on a mechaical Onan pump which is powered by the cam from a donor engine. I replace the diaphram on it mounted it on the engine and could not get a drop out of the pump, even after priming it. So now it's unto plan C which is what Boomer mentioned last week during a phone conversation. Pulse pump which many small engines have today. He mentioned I could connected the vaccum side of the pulse pump up to the dipstick tube. I was thinking maybe I could attach it to the breather which is in close proximity to the carb. Anyone have any other ideas out there?

Keep the Peace :cop: :peace:
Harry
Those pulse pumps are the best way to go . The easiest is the dip stick tube as it can easily be removed to install a vac. fitting . Make sure you have a good seal at the dip stick it's self and put the fitting about 3/4 sway up the tube . Mount your pump higher that the fitting so any oil build up will drain back to the tube .
Dave
Mad Tractor Builder
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