Re: [MV] G749 GMC Carb rebuild questions

From: Santoken (santoken@bright.net)
Date: Tue Dec 07 2004 - 17:33:55 PST


Well, after looking closely, and spending a few more hours with this
carb, and looking into responses from the earlier post...I'm still stumped.

So, this leads deeper, does anyone know what the fuel pressure should be
on a G749? You see, somehow or another I lost the original fuel pump so
I obtained an aftermarket Carter 24v fuel pump. It seemed to run fine
earlier, but I'm trying all options. The fuel pump that I installed is
rated for 5.5-10 psi...which from past experience should be well within
the required specs...but I'm not sure about this application and perhaps
the fuel pump is malfunctioning.

Or better yet, does anyone have the original fuel pump, and fuel pump
module box they'd be willing to part with?

Thanks!

Santoken wrote:

> List,
>
> AT the beginning of summer, I had my M215 running sweet. When you tried
> to start it, you didn't even hear the starter motor run because the
> engine seems to start running first. It started and ran that nicely.
>
> After sitting all summer, I started it to move it and it barely started
> and ran horribly. It was running entirely too rich. After I got it
> moved, I tore into the carb. Yeah, it was running WAY too rich. Seemed
> that the bowl was leaking fuel down into the carb just sitting there,
> not doing anything. I decide to do a rebuild.
>
> After paying the horrible money for a sub-standard kit, it still does
> the same thing. I have had that carb on and off so many times I can't
> count.
>
> Is there anyone out there familiar with that Holley that could give me a
> few pointers? This is the most bastard carb I've ever seen and since
> the carb kit didn't come with any literature, I could really use some
> outside knowledge on it.
>
> After running the idle mixture screws bottom, and dropping the float all
> the way down...it runs OK...just ok. When I back the screws out, it
> starts faltering. Adjusting the float does the same. When the float is
> set to proper height, and the air-horn off, I can see fuel dribble into
> the carb...I can't really see where it's coming from, tho.
>
> The idle circuit appears to be fine since the idle mixtures screws seem
> to effect its idle quality. The bowl is not cracked and the power valve
> is functioning properly. The kit that I got came with new metering
> orifice tubes but they look nothing like the old ones, have these been
> redesigned to repair some known problem? The old tubes had the base
> crushed shut, the new ones did not...and the orifice on the new ones is
> MUCH smaller...surely effecting the air bleed.
>
> Has anyone else ran across this same problem?
>
> Thanks,
>
> Kent
>
>
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