On Fri, 19 Nov 1999, Paul Hunt wrote:
> Rapid pumping does indicate empty float bowls. If you have the Hall-effect
> pump, rather than the transistor assisted points type, I don't trust them.
I don't know which one I have. All I know is, removing the pump is such a
pain, and me and gasoline don't get a long, so I got a pump that hopefully
wouldn't need much maintenance.
A couple of people have emailed me that they had the exact same problem I
have had in the spring, when it first got hot, but they still had winter
gas in the tank. In the middle of the summer, the problem went away.
> My V8 has one and started doing what you describe, in my case it was weak
> pumping, it was only taking itty-bitty strokes i.e. not enough throughput.
> I took the pipe off the carbs and fed it into a bottle while I watch the
> action of the pump. Couldn't see anything apparently wrong, and after a few
> minutes it just started pumping normally again. My pump is not a conversion
> so I cannot convert it back to points again at the roadside. I now carry a
> spare pump.
>
> I've never really understood 'vapour lock' in connection with our fuel
> systems. If the fuel level in the float bowls drop the valve opens. With
> the pump at the back of the car pushing, even if there was vapour in the
> pipes wouldn't it get pushed straight through to be followed by liquid fuel?
> Or is the theory that the pipe gets so hot that the liquid fuel also
> vapourises at that point? But that takes energy that would tend to reduce
> the temperature of the pipe, unless there was so much heat being generated
> in the engine compartment that there was more than enough to keep the
> vapourisation going. That's an awful lot of vapour. My factory V8 has
> never suffered from vapour lock even on a 90+ day stuck in traffic, with
> both fans on full time and the temp needle well into the red.
>
> PaulH.
> http://freespace.virgin.net/paul.hunt1/
> (or if that URL doesn't work try )
> (http://194.168.54.52/paul.hunt1)
>
> -----Original Message-----
> From: James Howard <jhoward@sextans.lowell.edu>
> To: MG list <mgs@autox.team.net>
> Date: 19 November 1999 04:32
> Subject: Stumbling
>
>
> >
> >I had a problem the other day with my 66 MGB/GT that I can't figure out.
> >It has been convereted to negative ground, and has a newish SU fuel pump
> >that has electronics controlling it rather than points.
> >
> >We live in Flagstaff, AZ, elevation 7000 ft. The nights are getting into
> >the 20's F, and I suspect that the gas we are using this time of year is
> >the winter formulation.
> >
> >We drove down to Sedona, which is at 5000 ft, and you drive a beautiful
> >two lane road through Oak Creek Canyon to get there. It was 95F when we
> >got there. On the way down, after driving for about 45 minutes, the car
> >started stumbling a little. I stopped to make sure the connections in the
> >ignition circuit were tight (they were), and continued on. On the way
> >back up, the stumbling returned, and finally the car quit. After opening
> >the hood, scratching my head, looking for anything obviously wrong for a
> >few minutes, I started it up again. When I turned the key to run, the
> >fuel pump went crazy for a few seconds, like it does when the float bowls
> >are empty after rebuilding the carbs. So, we drove up the road, when it
> >started stumbling again. I was thinking vapor lock, so we stopped for
> >lunch for an hour. After that hour, we had no further problems on the way
> >back to Flagstaff.
> >
> >I am thinking this was vapor lock. My Dad, who owned a then new 67 BGT in
> >Colorado, says he never had a vapor lock problem with it. So, he thinks
> >it is the fuel pump. I think that gasoline is a lot different now than it
> >was in 1967, and the winter gas in hot weather could cause this problem.
> >
> >I was wondering, what do you all think?
> >
> >Thanks,
> >
> >James Howard
> >
> >
> >
> >
>
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