| [GMCnet] Fuel Pump [message #129390] |
Thu, 09 June 2011 00:37  |
SergeL
Messages: 169
Registered: January 2011
Karma: 0
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Senior Member |
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The mechanical fuel pump on my 73, has more than one outlet, one goes to the
carb. And the other has been plugged off with a short piece of hose. The
pump looks new as does the carb. Can someone tell me what the extra output
is for? If that's what it is? I looked through the 73 manuals but I could
not find anything.
Thanks in advance
Serge
1973 GMC
Deming, NM
He who expects no gratitude shall never be disapointed
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| Re: [GMCnet] Fuel Pump [message #129391 is a reply to message #129390] |
Thu, 09 June 2011 00:54  |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
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Senior Member |
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Serge,
Although it works, it's the wrong pump. If you order a fuel pump for a Toronado with A/C you'll get that pump - the extra outlet is a return line to the tank to help eliminate vapor lock. A Toronado (no A/C) does not have that extra outlet, and neither to the GMC's. I believe the NAPA part for the correct pump is M-6108. The pump you have would be M-6109.
No need to worry about that extra port so long as the plug is good.
Larry Davick
the Mystery machine
1976(ish) Palm Beach
Fremont, CA
On Jun 8, 2011, at 10:37 PM, greatmoments60@hotmail.com wrote:
> The mechanical fuel pump on my 73, has more than one outlet, one goes to the
> carb. And the other has been plugged off with a short piece of hose. The
> pump looks new as does the carb. Can someone tell me what the extra output
> is for? If that's what it is? I looked through the 73 manuals but I could
> not find anything.
>
>
> Thanks in advance
>
>
> Serge
> 1973 GMC
> Deming, NM
>
>
> He who expects no gratitude shall never be disapointed
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
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| Re: [GMCnet] Fuel Pump [message #129530 is a reply to message #129391] |
Fri, 10 June 2011 00:40 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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The major problem with that pump is that we forget as to how long we
left that old plug until a fire starts.
I have been asked by insurance people to determine fire on GMC and had
to show them that that was one area where the fuel started spraying
fuel to start a fire from the hot exhaust manifold.
Same goes for fuel line from pump to carb. it should be steel all the
way wit no rubber.
We do not keep track of the time that that hose has been there.
On Wed, Jun 8, 2011 at 10:54 PM, Larry Davick <ljdavick@comcast.net> wrote:
> Serge,
>
> Although it works, it's the wrong pump. If you order a fuel pump for a Toronado with A/C you'll get that pump - the extra outlet is a return line to the tank to help eliminate vapor lock. A Toronado (no A/C) does not have that extra outlet, and neither to the GMC's. I believe the NAPA part for the correct pump is M-6108. The pump you have would be M-6109.
>
> No need to worry about that extra port so long as the plug is good.
>
> Larry Davick
> the Mystery machine
> 1976(ish) Palm Beach
> Fremont, CA
>
> On Jun 8, 2011, at 10:37 PM, greatmoments60@hotmail.com wrote:
>
>> The mechanical fuel pump on my 73, has more than one outlet, one goes to the
>> carb. And the other has been plugged off with a short piece of hose. The
>> pump looks new as does the carb. Can someone tell me what the extra output
>> is for? If that's what it is? I looked through the 73 manuals but I could
>> not find anything.
>>
>>
>> Thanks in advance
>>
>>
>> Serge
>> 1973 GMC
>> Deming, NM
>>
>>
>> He who expects no gratitude shall never be disapointed
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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--
Jim Kanomata
Applied/GMC, Fremont,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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| Re: [GMCnet] Fuel Pump [message #209132 is a reply to message #209127] |
Wed, 29 May 2013 11:13 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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If you crimp the third line and braze or solder it you should be OK. I ran that way for at least three years before getting rid of the mechanical pump.
NEVER use a rubber tube as it will eventually crack and squirt gasoline all over your engine and hot manifolds and you are certain to have a fire.
Emery Stora
77 Kingsley
Frederick, CO
On May 29, 2013, at 9:28 AM, Southmayd wrote:
>
>
> I also have a mechanical fuel pump with 3 lines. The center vent line was connected with a short 4" section of 1/4" that was plugged with a lag bolt in the other end. (And yes it leaked! I noticed a puddle of gasoline on the pavement after I warmed up the engine for 15 minutes. Likely also have accounted for poor gas mileage). I was fortunate not to have a fire!). I have put a new hose on with a more permanent cap for the time being.
>
>
> I do have a replacement mechanical pump M-6108 with two fittings ready to install.
>
> Question:
> Should I install the M-6108 to be ultimately safe and prevent this problem in the future. or,
> Install a longer vent line and try to route it back to the vent line near the filler on the drivers side of the coach?. I have heard that venting the fuel pump is good to prevent fuel leak off back to the carb under pressure after the engine is shut off.
>
> Your thoughts?
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