[Healeys] No Power
Bob Spidell
bspidell at comcast.net
Sat May 30 21:23:06 MDT 2009
re:
"I think SU pumps have a bad wrap"
Not necessarily. IMO, the problem with SU pumps is they use points to switch
the current. When the points open the induced magnetic field in the coil
collapses producing a back current which arcs across the points (similar to what
happens in an ignition coil). This arcing transfers metal with each occurrence,
and also produces ozone which exacerbates the arcing (that's why the electronic
end of the pump is vented). Eventually, the gap changes and/or the points stick
and the pump becomes intermittent or fails outright. The arcing is why SU pumps
went from nothing, to a capacitor to a diode (called a 'flywheel diode') across
the points to reduce the arcing. The final cure is a fully electronic pump,
with a Hall Effect and transistor-switched design (which solved my pump
problems--I've never had a contamination problem).
Also, the diaphragm can get stiff from age and non-use.
Bob
Alan Seigrist wrote:
> Steve -
>
> It's hard to say without more data, but sounds like fuel starvation.
> If cars sit for a long time, the fuel tanks rust up and the rust scale
> clogs up the fuel pump causing it to work overtime. The fact that it
> worked for a short while suggests this is your problem (ie it took a
> few minutes to suck the rust into your system)
>
> I'd say drain and flush your tank and take out the fuel pump and
> dissassemble and clean.
>
> To be honest as I get older I think SU pumps have a bad wrap. They
> actually work fine, but they fail usually when they get clogged with
> crap.
>
> All cars I buy, I ALWAYS pull the tank and fuel pump and clean them
> out thoroughly.
>
>
>
--
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Bob Spidell San Jose, CA bspidell at comcast.net
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