| Anyone have a loose fuel pump? [message #332385] |
Mon, 21 May 2018 18:36  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Along with so much else, I am putting on a new fuel pump.
(The other broke when the too small engine stand crashed.)
I am used to being able to hand pump an engine driven pump, and this new one, I cannot.
Well, with lots of leverage, I sort of can, but it is not what I am used to.
If you have one, new or old lying around, could you please pick it put and see if you can pump it by hand?
Thank you
Matt
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: Anyone have a loose fuel pump? [message #332386 is a reply to message #332385] |
Mon, 21 May 2018 18:50  |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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When I first got started referbing my GMC, I removed the mechanical pump and put a plate over the hole. Then stuck a Carter 4070 in the line back at the tanks. Never looked back. JWID
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
[Updated on: Mon, 21 May 2018 18:51] Report message to a moderator |
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| Re: Anyone have a loose fuel pump? [message #332387 is a reply to message #332385] |
Mon, 21 May 2018 18:50 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Matt,
During my recent engine rebuild/replacement, I found the new fuel pump very stiff as well. I got a "Carter" mechanical pump off of Ebay, or Amazon, can't remember which. I could barely move the lever. There is not much to hold onto on the pump end, but it seemed very stiff to me. I chalked it up to getting older and weaker. 
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Anyone have a loose fuel pump? [message #332390 is a reply to message #332385] |
Mon, 21 May 2018 19:51 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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I have one I removed from a 403 about 3 months ago. It is laying on the floor in my hangar. What do you need and how soon? I could drive up there and check it out for you if necessary.
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Anyone have a loose fuel pump? [message #332396 is a reply to message #332385] |
Tue, 22 May 2018 08:49 |
Tilerpep
Messages: 404
Registered: June 2013
Location: Raleigh, NC
Karma: 7
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I took off a working pump and replaced it with a new one to diagnose a noise two years ago. No change, so presume the pump on my shelf was/is fine all along. Could not budge it by hand just now
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC
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| Re: [GMCnet] Anyone have a loose fuel pump? [message #332399 is a reply to message #332398] |
Tue, 22 May 2018 10:12 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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There are usually 2 springs in modern mechanical fuel pumps. One whose
purpose is to keep the operating lever in contact with the cam lube, is
quite strong. The other spring, which actually presses against the
diaphragm, is the one that actually pumps the fuel. It has about 3 - 5
pounds pressure. It is compressed by the movement of the operating lever,
and relaxes against the diaphragm. If there is an equal pressure against
the other side of the diaphram, like there would be when the carb needle
were closed, then that small spring does not move the diaphram and no
pumping takes place until the float needle opens. So, now you know how the
mechanical pump regulates fuel pressure.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Tue, May 22, 2018, 7:55 AM John R. Lebetski
wrote:
> Maybe they increased the spring load to keep them from sticking or to keep
> contact for the "racer" market?
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
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| Re: Anyone have a loose fuel pump? [message #332516 is a reply to message #332385] |
Thu, 24 May 2018 12:43 |
lw8000
Messages: 201
Registered: July 2012
Location: S.E. Michigan
Karma: 1
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Matt,
I too replaced our fuel pump twice in the past 4 years while diagnosing fuel issues... with a brand new Carter in each case, and noticed the same thing. Apparently it's normal. Not a single problem with them (knock on wood).
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan
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