| [GMCnet] Low fuel pressure entering Onan Carb [message #86672] |
Mon, 31 May 2010 09:35  |
Alan LaVoisne
Messages: 51
Registered: September 2009
Location: Ortonville, MI
Karma: 0
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Hi all,
I have a 75 Glenbrook that has sat for a while. Last fall, the little
bubble in the fuel pump was stuck, I got it unstuck and the generator ran
great at idle but really rough and rich when under load. In hindsight, I
think it was running with the choke half closed but I don't remember
checking or noticing at that time (last fall). Over the winter I had all
the fuel lines replaced. Now with the new fuel lines, it will not run much
at all. The fuel is entering the carburetor at a drizzle and has small air
bubbles coming through. The fuel pump is working. If I jumper the fuel
pump and let it run for a few minutes without the generator running, then
start the generator, the generator will idle decent (choke half closed) but
a load will stall it. I am wondering if there is a replaceable fuel filter
I should replace or if the fuel pump is just not up to par. Last fall that
fuel pump had excellent pressure coming out of it (checked at the output of
the fuel pump and before the fuel filter). So I am debating new fuel pump
and if there is such a thing, a new fuel filter. Any other ideas?
Thanks for all your help. It is really great.
Alan LaVoisne
75 Glenbrook.
88k miles
Ortonville, MI
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1975 26' Glenbrook
Mostly Original
Ortonville, MI
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| Re: [GMCnet] Low fuel pressure entering Onan Carb [message #86683 is a reply to message #86672] |
Mon, 31 May 2010 10:37  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Thre is a filter at the liwer part of your pump.
You can back flush it.
On Mon, May 31, 2010 at 7:35 AM, Alan LaVoisne <alan@lavoisne.net> wrote:
> Hi all,
>
> I have a 75 Glenbrook that has sat for a while. Last fall, the little
> bubble in the fuel pump was stuck, I got it unstuck and the generator ran
> great at idle but really rough and rich when under load. In hindsight, I
> think it was running with the choke half closed but I don't remember
> checking or noticing at that time (last fall). Over the winter I had all
> the fuel lines replaced. Now with the new fuel lines, it will not run much
> at all. The fuel is entering the carburetor at a drizzle and has small air
> bubbles coming through. The fuel pump is working. If I jumper the fuel
> pump and let it run for a few minutes without the generator running, then
> start the generator, the generator will idle decent (choke half closed) but
> a load will stall it. I am wondering if there is a replaceable fuel filter
> I should replace or if the fuel pump is just not up to par. Last fall that
> fuel pump had excellent pressure coming out of it (checked at the output of
> the fuel pump and before the fuel filter). So I am debating new fuel pump
> and if there is such a thing, a new fuel filter. Any other ideas?
>
> Thanks for all your help. It is really great.
>
> Alan LaVoisne
> 75 Glenbrook.
> 88k miles
> Ortonville, MI
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Low fuel pressure entering Onan Carb [message #86687 is a reply to message #86683] |
Mon, 31 May 2010 10:52 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Turn the big nut on the bottom on the pump and the filter will come out of the bottom. Clean it and reinstall in reverse order.
The air bubbles tell me you have a leak on the input side of the pump and it is sucking air. How much gas do you have in the tank?
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Low fuel pressure entering Onan Carb [message #86716 is a reply to message #86688] |
Mon, 31 May 2010 17:17 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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| emerystora wrote on Mon, 31 May 2010 08:55 |
> Turn the big nut on the bottom on the pump and the filter
> will come out of the bottom. ...
>
> The air bubbles tell me you have a leak on the input side of
> the pump and it is sucking air. How much gas do you have in
> the tank?
OR, the hose from the tank to the pump might have developed a small crack that doesn't leak fuel but might allow it to suck in air when the pump is running.
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For trouble shooting, You can connect the pump directly to a boat style gas tank for small outboards. (You might be able to borrow one if needed.) This will tell you if the problem is the generator or the coach side.
As stated the reusable filter is in the bottom of the pump. Above that is the plunger and two check valves. All can be cleaned with carb cleaner. Reassemble in reverse of the disassembly. It is not hard to do.
Anyone know where to get the gasket in the bottom of the filter? (or what to use to make one?) My 6k's is getting a bit ragged.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] Low fuel pressure entering Onan Carb [message #86765 is a reply to message #86716] |
Mon, 31 May 2010 22:40 |
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As stated the reusable filter is in the bottom of the pump. Above that is the plunger and two check valves. All can be cleaned with carb cleaner. Reassemble in reverse of the disassembly. It is not hard to do.
Anyone know where to get the gasket in the bottom of the filter? (or what to use to make one?) My 6k's is getting a bit ragged.
Mike, I bought both the filter and the gasket at Kenworth (I think) in Reno. This before I found out that the pump was bad. I can ship both to you for $5.00 if you want. I replaced mine with a NAPA, cost about $35.00 IIRC.
geo groth '73 260 Sequoia
Carson City Nevada 89703
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| Re: [GMCnet] Low fuel pressure entering Onan Carb [message #86818 is a reply to message #86765] |
Tue, 01 June 2010 11:00 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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| ggroth wrote on Mon, 31 May 2010 20:40 |
> ...Anyone know where to get the gasket in the bottom
> of the filter? (or what to use to make one?) My 6k's is
> getting a bit ragged.
Mike, I bought both the filter and the gasket at Kenworth (I think) in Reno. This before I found out that the pump was bad. I can ship both to you for $5.00 if you want. ...
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Sounds good, I'll send you a PM.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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