[Spridgets] Fuel sucking vacuum problem on Pinky youtubes to follow.

Jim Johnson bmwwxman at gmail.com
Sat Oct 9 14:20:26 MDT 2010


Lin,

"Seeing" fuel go through the filters is not a sufficient diagnostic...  The
carbs require a given rate of fuel flow...  Any less than that rate and the
carbs will gobble up fuel faster than the float bowls can supply eventually
drying them out and starving the carb of fuel so engine dies.

The fuel pumps and carbs were designed to use a certain rate of flow.
Filters slow down the rate of flow..  The car came with one (1) filter...
just upstream of the carbs in the engine bay if I am not mistaken.  Adding
additional filters will reduce the fuel flow rate.   This problem is
commonly seen in my old BMW motorcycles when people put inline fuel filters
on them...

First thing I would do is start the car. When it stops turn the key off
immediately. Now check the float bowls for fuel...  If they are dry or
nearly so, you don't have sufficient fuel flow to the carbs.  If they are
full, you may, as Jon said, have a blockage of some sort in the vents...

Another test would be to calculate the volume of fuel flow required over,
say, 10 seconds. Remove the fuel line from the carbs and point it into an
empty plastic jug. Turn the key (fuel pump) on for ten seconds then off.
Now measure the volume of fuel you have and see if it matches what it should
be.

Cheers!!
Jim

On Sat, Oct 9, 2010 at 2:43 PM, Jon Paschke <jpaschke at bak.rr.com> wrote:

>  Sounds to me like maybe you have the vents to the carb bowls blocked.
>
>
>
> On 10/9/2010 10:47 AM, Linda Grunthaner wrote:
> > List,
> > I am currently back to a reoccurring problem on my 1275 engine. I can
> start
> > her fine carbs are clean ( I keep them clean) she has a new good running
> > electric fuel pump and then after running for 5 minutes of running she
> has
> > no gas. I have 2 filters at the electric pump on ether side so i can see
> the
> > gas coming in and going out of the pump), I blew air in the fuel line
> from
> > the tank, and no blockage was found. I even blew air into the fuel tank
> to
> > be sure to clear any deposits (Frank's tip) I can get it to run via a
> soda
> > bottle filled with fuel indicating zero clog at the line. It appears that
> I
> > have some kind of suction blockage so I removed the gas cap and nothing.
> If
> > I wait a day it is fine again for another 5 to 10 minutes of running then
> no
> > gas. Any tips? BTW tank is shiny inside and clean and I have fuel.
> >
> > I remember when I first posted this problem last year (yes I STILL can't
> > drive her off the driveway 12 months later) some have said not to have 2
> > filters, some have said put the filter at the tank and others have said
> > something else. I even recall someone saying I have a vacuum block. I am
> > thinking I'll just remove both filters and give her a try and get back to
> > the list with my results today. If it is a block via some type of sucking
> > vacuum how do I get rid of that? Youtubes to follow.
> >
> > Thanks Linda
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-- 
Cheers!!
Jim
"The problems that exist in the world today cannot be solved by the level of
thinking that
created them."-Albert Einstein


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