[Healeys] Misfire

Alan Seigrist healey.nut at gmail.com
Sun Dec 2 04:39:39 MST 2007

Peter -

If your fuel pump is in the same location as the original fuel pump, you may
be experiencing vapor lock.  The fuel pump is located right above the
exhaust on a 100, and when you go for a long trip the heat can build up in
that area.  I fixed my 100 simply by wrapping some header tape around the
exhaust pipe for the section that passes under the fuel pump and battery
tray and I haven't had a problem since.  I'm sure that's what it is.  It's
summer in OZ and it's hot.

Also, be a little wary of the old Facet square body pumps, they get weaker
with age.  If you find your car having trouble heading up hill with a 1/4
tank, it could be the pump is getting old.

FYI the A90 (which I have one) has its mechanical fuel pump mounted right
next to the exhaust manifold, so it will be very prone to vapor lock in hot
climates like OZ.  Best solution on the A90 is to fire the old mechanical
pump from a clay pigeon launcher and get a couple of pot shots with a 12
guage.  It's what us Americans do best, shoot stuff.  Mount up a facet or
bendix pump and you are like new.



On Dec 2, 2007 6:57 PM, Peter Linn <greylinn at ozemail.com.au> wrote:

> G'day list - hope someone might be able to help me diagnose this:
> occasionally, and with no particular pattern, the Ward Special's BN1 motor
> misfires. I can be cruising on a light thottle at, say, 2000 rpm in top,
> and
> without warning the car misfires and loses power. This happened again a
> couple
> of times today on an 80 mile round trip to the AHOC Qld Christmas lunch.
> All
> dash indicators show normal. I've found that if I dip the clutch & rev the
> motor, it will  clear, often with a backfire and (I'm told by people
> following) a puff of black smoke. I suspect a fuel issue of some sort - I
> have
> a Facet fuel pump which appears to be functioning OK; there are 2 filters
> in
> the line, both of which I've changed; I've checked the float chambers and
> they're clean. The carbs have been overhauled in the last few years and
> I'm
> pretty handy at setting them up after 40 years with SU's. THe only minor
> indication of anything inconsistent is that no. 2 plug looks a bit darker
> than
> the other 3.
> Any ideas?
> Cheers
> Peter Linn
> Brisbane Oz
> BN1 Ward Spl coupe

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