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Mr. Onan Fuel Pump Mostly Working, But... [message #298697] Tue, 05 April 2016 17:32 Go to next message
A Hamilto is currently offline  A Hamilto   United States
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I put the Onan fuel pump back together and tested it and it pumps gas. But when I was disassembling my test setup, I noticed that there was some gas that had seeped out of the bottom twist on cap. There isn't anything wrong with the gasket, so I don't have much hope that replacing it will fix the problem.

Is there any kind of gasket sealant that will hold with gas standing against it continuously?

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Re: Mr. Onan Fuel Pump Mostly Working, But... [message #298698 is a reply to message #298697] Tue, 05 April 2016 17:46 Go to previous messageGo to next message
SteveW is currently offline  SteveW   United States
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Apologies for a bit of a hijack - but may I pose a question ?

How long do y'all have to "prime" the Onan before it'll start ??

With my old fuel pump - 10 seconds would do. With my new fuel pump - it take at least a minute !!

Thanks in advance,

Steve W
1973 23'
Southern California

Steve W 1973 : 23' Southern California

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Re: Mr. Onan Fuel Pump Mostly Working, But... [message #298719 is a reply to message #298697] Tue, 05 April 2016 20:30 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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A Hamilto wrote on Tue, 05 April 2016 18:32
I put the Onan fuel pump back together and tested it and it pumps gas. But when I was disassembling my test setup, I noticed that there was some gas that had seeped out of the bottom twist on cap. There isn't anything wrong with the gasket, so I don't have much hope that replacing it will fix the problem.

Is there any kind of gasket sealant that will hold with gas standing against it continuously?

You mean you can't see anything wrong with the gasket.

Are both surfaces clean and smooth?
What power magnification did you use for the inspection?
If it is still a Bendix/Facet/Purolater pump, that gasket can be replaced by the right O-ring. The size needed is uncommon, but is available.

Matt - Hold up at FMCA Cinci.

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

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Re: Mr. Onan Fuel Pump Mostly Working, But... [message #298722 is a reply to message #298698] Tue, 05 April 2016 20:34 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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SteveW wrote on Tue, 05 April 2016 18:46
Apologies for a bit of a hijack - but may I pose a question ?

How long do y'all have to "prime" the Onan before it'll start ??

With my old fuel pump - 10 seconds would do. With my new fuel pump - it take at least a minute !!

Thanks in advance,

Steve W
1973 23'
Southern California

Steve,

If you replaced that pump with a similar pump, then you probably need to replace a bunch of rubber fuel line too.
If you put in a Mr. Gasket pump, it will work, but it is not a shadow of the Bendix pump.

Matt Hold up at FMCA Cinci off to the Serpent Mounds tomorrow

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

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Re: Mr. Onan Fuel Pump Mostly Working, But... [message #298724 is a reply to message #298719] Tue, 05 April 2016 21:38 Go to previous messageGo to next message
A Hamilto is currently offline  A Hamilto   United States
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Matt Colie wrote on Tue, 05 April 2016 20:30
...You mean you can't see anything wrong with the gasket.
Are both surfaces clean and smooth?
What power magnification did you use for the inspection?
If it is still a Bendix/Facet/Purolater pump, that gasket can be replaced by the right O-ring. The size needed is uncommon, but is available.

Matt - Hold up at FMCA Cinci.
Replacement gasket is about $20 with shipping. I figured a tube of the right sealant would be less than $10.

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Re: [GMCnet] Mr. Onan Fuel Pump Mostly Working, But... [message #298729 is a reply to message #298722] Wed, 06 April 2016 06:06 Go to previous messageGo to next message
Jim Miller is currently offline  Jim Miller   United States
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On Apr 5, 2016, at 9:34 PM, Matt Colie wrote:

> If you put in a Mr. Gasket pump, it will work, but it is not a shadow of the Bendix pump.

I agree wholeheartedly with Matt’s statement. There was a very good reason the Bendix pump was used on millions of military engines: it is eminently reliable and maintainable. I have some 50 year old turbine APU sets which use a 24 volt version of the Bendix and after a bit of TLC to clean and maintain them they still work as well today as they did when new….and they have to pump far more fuel per minute on a turbine (about 40 GPH) than they do on our Onans.

—Jim Miller
1977 Eleganza
1977 Royale


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Jim Miller 1977 Eleganza II 1977 Royale Hamilton, OH

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Re: Mr. Onan Fuel Pump Mostly Working, But... [message #298755 is a reply to message #298697] Thu, 07 April 2016 00:07 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
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NAPA has that bottom gasket in a kit for $10.00. I replaced mine last year. I'm not anywhere that I can look up the part number right now.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

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Re: Mr. Onan Fuel Pump Mostly Working, But... [message #298768 is a reply to message #298697] Thu, 07 April 2016 09:40 Go to previous message
SteveW is currently offline  SteveW   United States
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Thanks...

I foolishly didn't even consider a rebuild kit and replaced it with this from JimK:

http://www.appliedgmc.com/prod.itml/icOid/1492

ONAN FUEL PUMP EXHACT FIT
Price: $129.95
REPLACEMENT FUEL PUMP FOR 4K AND 6K ONAN GENERATOR. COMES WITH BUILT IN FUEL FILTER.EXACT FIT NO MODIFICATIONS NEEDED.GM28-044E-2

And I did replace about two feet of fuel line...

Perhaps I should look for an original bendix, rebuild it, and do a comparison.

Steve W
1973 23'
Southern California

Steve W 1973 : 23' Southern California

[Updated on: Thu, 07 April 2016 09:41]

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