The "rattle" pump is pressure sensitive and cuts off when not needed. As
far as recirculation goes when used with a diesel, rattle pumps are used a
supplements for either weak injector pumps (which keeps is original
recirculation plumbing), or as replacement "lift pumps" which send fuel to a
good IP which, again, retains in recirc. feature.

Bill Longyard


"Gordon Wedman" wrote in message
news:HAPxh.34319$Fd.30102@edtnps90...

"William Longyard" wrote in message
hlink.net...
If you're going to use an electric, I would recommend a "rattle" pump
available at any autoparts store. They cost $30, are self priming, cut
off when not needed, and last a long time. I've used them on many gas,
and one diesel, engines. They've never let me down.

My 2 cents,
Bill Longyard



"Frogwatch" wrote in message
ups.com...
Years ago, I put an electric fuel pump in line with my mechanical pump
to help in bleeding the fuel system. When I turned the key, it would
run till the system was pressurized and would then stop. If it ran a
lot, I knew I had to bleed the system. It finally had the diaphragm
go bad so I replaced it but was unable to get an exact replacement.
The new pump runs ALL the time unless I turn the key off and if I
allow it to run all the time it gets hot. Did I get two different
kinds of pump? Was the first a "demand pump" that turns off when the
output side is pressurized? Neither set of directions said anything
about this.


cut off
when not needed

How do they know when they are not needed?

Sounds like the first pump had some kind of pressure switch included while
the second does not. I thought most diesel engines had a fuel
recirculation line that led excess fule from the injectors back to the
tank. As such when you run an electric pump it just pumps fuel through
the lines, across the top of the injectors and back to the tank. Not a
problem if it continues to run while switched on.