1989 Onan 6500

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Deano2002

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Morris, IL.
My fuel pump on the onan generator is acting up and I hear the knocking going on, no, not the engine knocking, also very little gas coming thru the clear fuel filter and the tank is near full. All the fuel pumps I see on ebay or amazon are round bodied not square box looking ones, are they the same or are the older square ones still out there? I'm hoping not to re-plumb
 

Deano2002

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Morris, IL.
Just for your information, I found the original fuel pump that was on my generator for 51.00 plus shipping. Not sure why one would go through an Onan dealer to pay 3 times as much and have to make modifications to the fuel lines and mounting when this is the exact replacement original equipment. This of course is for older Onans of course and, it lasted 29 years with 700 plus hours, maybe would have lasted longer if they had  a filter in front of it.
 

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Gary RV_Wizard

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I've always been amused at the folks who insist on buying Onan brand filters and oil for their genset, at 3x-4x the going price.  Onan doesn't even make filters and they certainly don't refine oil, yet many feel it the only safe brand to use.
 

Deano2002

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Morris, IL.
well, after thinking all was well when I replaced the fuel pump I found that the see through fuel filter was still not filling up but, rather barely enough fuel to keep the genny running. If the fuel tank is full it runs like it should but, when I get near half it will start (I think) sucking air from some place. I bought a bicycle pump and blew back through the fuel line thinking maybe something was collecting at the syphon tube then, I used a brake line vacuum pump to suck the fuel back until the filter was full and connected the line back to the fuel pump. That seemed to make no difference. I either have a bad pickup tube in the tank or I have a bad fuel line between the genny and the tank but, I would think I would be leaking fuel if the later. Another project before it gets cold out here. At least we made the 1450 mile trip without major incident and got 6.82 mpg pulling the toad, not bad for an old carbureted 454. That was going anywheres from 35 mph up the mountains to, 75 mph going down the hills. I tried to keep it around 65 mph on flat land
 

Deano2002

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Apr 21, 2013
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Morris, IL.
posting on my old thread, I thought i had another about the end housing bearing but anyways, I started to disconnect and pull the generator out of the motorhome yesterday and looks pretty straight forward getting the end housing off (I hope) but, looking into the generator side I see some white plastic pieces laying in there which worries me. The unit worked just find up to the point I heard the loose bearing and shut the unit off. My other concern is that I don't see any parts for this 30 year old unit online, at least from Onan. If there are broken no replaceable parts I will have to consider buying a new Onan 7K output one or and aftermarket equivalent. I sure don't want the noise of a 2 pole generator spinning at 3600 rpm and it's noise. Are there any other alternatives for motorhome generators?
 

DonTom

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Apr 21, 2005
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Auburn, CA or Reno, NV
My fuel pump on the onan generator is acting up and I hear the knocking going on, no, not the engine knocking, also very little gas coming thru the clear fuel filter and the tank is near full. All the fuel pumps I see on ebay or amazon are round bodied not square box looking ones, are they the same or are the older square ones still out there? I'm hoping not to re-plumb
Replace it with a very low PSI fuel pump. 2 to 4 psi. I bought mine at AutoZone, while in Yuma, AZ. Looks a lot better than the cheap one Onan uses. Fits the same way, same type of screw-on filter and all.

Edit: I now see that was a very old post. But the info. stays the same anyway.

-Don- Reno, NV
 
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Old_Crow

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Nov 20, 2016
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Tom's Place, California
Took my Onan 5.5k in to an Onan shop when it quit making electricity. It would run fine, just no power output. I live in my coach full time, so no facility to drop it and fix it myself.
They told me the stator was bad, and there are several small, plastic parts behind the stator that they normally replace while doing the stator job. Rational is that they are the same age as the generator, and if they fail shortly after the stator replacement, you have to pull the stator back off to replace them.
The quote for the job was in the $2300 range. My generator was also smoking and using oil. When I mentioned that, the combined cost of the stator and the engine rebuild approached the cost of a new generator.
I was able to find a lightly used(under 150 hours)7k at an RV salvage yard and have it installed for $2900.
 

Deano2002

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Apr 21, 2013
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Morris, IL.
2900 with 150 hours is fair price considering a new 7K is 5600.00, I don't see 6.5's anymore and, any ebay used ones are 2-3k$ with over 2k hours. I hope someone points me to a service manual to get this thing apart, like I say it was generating until I shut it off, maybe not too many parts have to be replaced if I can find them.
 

Old_Crow

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They had a 5.5kw that was $600 less, but ran into problems getting it out of the coach it was in, so agreed to split the difference with me on the 7kw. Didn't really need the 7kw, as the coach had a 5.5kw originally, but I needed something right away, so I took them up on the deal. Helps to know I'm not taxing my generator even when I'm running both a/c's full blast.
 

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