Fuel Pressure and Pump?

[Rodney Fulk]

I meant in tank not inline to be replaced... Personally I think if you have
an inline pump you should not have an in tank pump.
Anyhow, the boneville pump is a cylinder for the most part.
It is mounted I believe with circular clamps to the sending unit and has
standard type spade
connectors.


-----Original Message-----
From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
Behalf Of Rodney Fulk
Sent: Friday, January 18, 2002 10:21 PM
To: diy_efi at diy-efi.org
Subject: RE: Fuel Pressure and Pump?


As an add on to this.. A friend had an inline pump added to his normal flow
for a NO2 system. Within a very short period of time (In a months time) the
in tank pump disintegrated for some reason and this took out the inline pump
as well. I would think a new inline pump is in order. It is more then likely
that the current pump is far less then is needed.
I know they do size the pumps for the motor so that you don't have too big a
pump. Otherwise if you have too big of a pump the gas will get too hot and
this will effect your engine. The fuel pump uses the fuel to cool it.

SOME in tank fuel pumps are pretty universal. I have a fuel pump for my LT1
caprice that is for a '98 Super Charged Bonneville. Puts out 50gph instead
of the 35gph pump my original pump put out. I won't likely install it until
I am a little closer to needing it but with a 23 gallon tank in my car I am
guessing the fuel won't get overly warm if I run it for a little while...

My guess is your pump is no where near the 35gph the caprice has and my
caprice pump is not overly hard to overpower with a few mods...

-----Original Message-----
From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
Behalf Of Shannen Durphey
Sent: Thursday, January 17, 2002 9:39 AM
To: diy_efi at diy-efi.org
Subject: Re: Fuel Pressure and Pump?


In this case, it sounds like the factory pump may be insufficient.  Is the
factory LT1 regulator still on the fuel rails?  If it is not damaged, then
it
should be regulating pressure to factory levels, provided there is
sufficient
fuel volume.

One quick test to check the pump's ability to provide pressure would be to
pinch
the return line and watch the pressure rise on a gauge.  If it does not rise
considerably, the pump is not going to work.

You should also check volume.  You can do this indirectly by driving with
the
gauge installed and watching pressure changes.  Accelerate, power brake,
drive
up a large hill.  If the pressure is consistently at 35 psi, and the above
"pinch off" test indicates that the pump can build pressure, then you may
have a
bad regulator.  But if fuel pressure drops way off, then insufficient fuel
is
being delivered to the engine.  Providing the fuel filter is not plugged,
the
pump would be the most likely suspect.

If the diagnosis pointed to the tank, I would first try to replace the
in-tank
pump with something able to provide enough fuel.  I've had to troubleshoot a
few
draw-through, two pump systems, and the in tank pump can sometimes present
considerable restriction.  If the in tank pump can provide a large volume of
fuel at low pressure, then a two pump system is a reasonable option.  But
using
an in-line pump to draw fuel out of the tank can cause problems, imhe.

Shannen

Manuel Desantos wrote:
>
> You can run a second in-inline pump with the stock pump.
> I'd get an adjustable Fuel Pressure Regulator.
> You can also try and run the in-line and turn off the in-tank pump and
> see if there is enough flow through the in-tank pump.  If there isn't
> enough flow then I'd remove the in-tank pump and just run an in-line.
>
> -----Original Message-----
> From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org] On
> Behalf Of Whit
> Sent: Friday, January 18, 2002 11:37 AM
> To: diy_efi at diy-efi.org
> Subject: Fuel Pressure and Pump?
>
> I'm running an LT1 in my 89 Jeep cherokee and am having fuel pressure
> problems.  I am wondering if the stock fuel pump will do the trick.  The
> stock pump was meant to run FI on the Jeep at about 35 lbs.  After
> intalling
> the motor it is still running about 35 lbs and I understand the LT1 is
> supposed to run in the mid 40s. I bought a new regulator but my gut feel
> is
> that the stock pump is either inadequate or it needs to be replaced.
> Any
> have exprerience here?  What are options here?  Can I run a second
> inline
> pump?  If so, do I need the stock pump at all?
>
> Thanks,
> Whit
>
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