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Guenter Scholz - 24 Oct 2006 19:26 GMT

in general, can one cut the fuel delivery line (I know the return line is OK
to open... just finished doing that). I'm supposing that if the pump has a
diaphragm, it should be OK... if not there could be some fuel spilling out.
Is it just a 'bit' or lots????

thanks for any hints, guenter

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Jens - 25 Oct 2006 00:12 GMT

Hi Guenter

I think I don't understand the question, because why would you want to
do it?

Anyway, the fuel pump is a centrifugal pump which build up a
differential pressure between its input and its output. Two fuel pumps
are connected in series to be able to provide sufficent pressure to the
injection system.

Each pump has an internal pressure limiter and a check valve at its
output. The check valve ensures that the pressure is kept, also when
the engine is stopped (a low pressure will allow vapors to build up and
consequently cause starting problems).

Btw: In CIS-E injection system, a fuel accumulator is fitted in the
fuel system to have a certain volume of fuel to maintain the pressure.
In later systems, the fuel rail serves that purpose.

So yes, you can cut the fuel line, and the fuel will be pumped out of
the cutted line (so, why would you do that?)

The capacity of the fuel pumps is verified by disconnected the fuel
return line and collecting the fuel (whith engine off and ignition on).
This check that the fuel pumps can provide enough pressure to overcome
the threshold of the fuel pressure regulator, and that it can provide
enough fuel flow. The specification is max. 35 seconds to pump 1 liter.

Does that help you?

/Jens

> in general, can one cut the fuel delivery line (I know the return line is OK
> to open... just finished doing that). I'm supposing that if the pump has a
> diaphragm, it should be OK... if not there could be some fuel spilling out.
> Is it just a 'bit' or lots????
>
> thanks for any hints, guenter

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Guenter Scholz - 25 Oct 2006 01:10 GMT

>Hi Guenter
>
>I think I don't understand the question, because why would you want to
>do it?

thanks for that jens, the fuel line (to engine) has a pinn hole leak
..... too much salt on the roads here in Ontario. I need to cut out a few
cm or so of damaged line and replace with rubber hose (sutable fuel line
grade and high pressure of course). Consequently I need to cut the metal
pipe. I'd rather not have gasoline spilled all over in large quantities.
I expect some fuel to leak out of course, but was hoping that putting the
clamped rubber hose on quickly it might not be too bad. I was hoping that
typical fuel pumps might be of the diaphragm type and so assure no leakage.

cheers, guenter

ps this is my daughters Cavalier (Chevrolet) which I hope to make last 6 more
months before junking it.

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Wan-ning Tan - 25 Oct 2006 13:10 GMT

According to GM, the pressure can be released by unpluging the fuel pump
connector then running the engine unitl it stalls.

The pump connector is probably around the fuel tank. If it has similar
configuration as the Corsica I just worked a few days ago, the tank is
before the rear axle and the connector is just above the axle.

Like what Colton said, the residue pressure is not that much and won't
last, but the open end must be higher than the fuel level in the tank,
otherwise the fule will just keep draining.

I assume the leaking pipe is the metal segment going to engine. There
must be a small segment near the tank that is rubber (so the tank can be
lowered a little without disconnecting). Crimp the hose there to stop
the flow.

>>Hi Guenter
>>
[quoted text clipped - 14 lines]
> ps this is my daughters Cavalier (Chevrolet) which I hope to make last 6 more
> months before junking it.

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Colton Motor Express #6Here! - 25 Oct 2006 02:14 GMT

>in general, can one cut the fuel delivery line (I know the return line is OK
>to open... just finished doing that). I'm supposing that if the pump has a
>diaphragm, it should be OK... if not there could be some fuel spilling out.
>Is it just a 'bit' or lots????
>
>thanks for any hints, guenter

It will spill a cup or so , but you need to get the end of it up
higher than the fuel level or it will continue to siphon... put a
rubber hose on it and get that up in the air. -gar

--
BE HAPPY .. .. DON'T HURRY ..
http://coltonmotorexpress.blogspot.com/
79 Georgie Boy 33' Luxury Liner
81 MBZ 300td turbo stick shift [Tow-Car]

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Guenter Scholz - 27 Oct 2006 02:39 GMT

>>in general, can one cut the fuel delivery line (I know the return line is OK
>>to open... just finished doing that). I'm supposing that if the pump has a
[quoted text clipped - 6 lines]
>higher than the fuel level or it will continue to siphon... put a
>rubber hose on it and get that up in the air. -gar

thanks for that, appreciated. sounds like I can go ahead and cut
the line 'fast' with some snips. then use a pipe cutter on the fuel line
after I can bend it away to get access to the pipe for rotating the cutter.
Followed by putting the hose on....

cheers and thanks, guenter

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