re: SPICA fuel cutoff microswitch replacement

["Tony Sims" <simstony@domain.elided>]

Greg wrote:

>my 74 spider's fuel cutoff circuit isn't working properly. I had it in
>Bruce Metras' shop in San Rafael (good guy) and trust him when he says the
>solenoid and rest of the circuit is fine and that the problem is most
>likely the microswitch.

>How difficult is it to fix the microswitch? How involved is it?

From the Gospel according to Ingram:
"Replacing the micro-switch at the bottom of the pump requires removal of the
pump from the engine.  Since the micro-switch and the de-cel (function of the
fuel cam) are a redundant circuit, I do not recommend removing the pump for
switch repairs alone unless unless the pump requires rebuilding.

With everything set on specification, detonation during deceleration should be
minimized provided the driver refrains from driving with trailing throttle
(foot on throttle)."

So, it's a little involved, but not beyond shade-tree mechanical skills
(speakin' from experience here).  Wes sells the micro-switch for $48.  No
disrespect to Mr. Metras, but the guy who arguably knows the most about these
pumps thinks a bad micro-switch would not allow your car to backfire badly if
the pump is adjusted correctly and all other parts are functioning.

>Or is this
>the time to consider a conversion to carbs? I was actually hoping to keep
>the SPICA going for a bit longer.

I'm NOT unbiased on this issue, so take my advice with that in mind.  Anything
that must be done up to and including pump replacement will be less expensive
and difficult than converting to carbs, and you'll lose the uniqueness of
Spica and the reliable, no-fuss operation.  I say that in relation to the
retail price of the carb conversion parts ($1290 complete from Centerline with
a proper manifold, even more from IAP without the manifold).  If  you can find
the bits used or at a discount, you might be able to convert for less than the
price of a reconditioned Spica pump (currently $685 for AROC members from Wes
Ingram).

>Right now I just put up with the occasional barking. I've gotten where I
>can usually keep from a full backfire "POP" in most driving.

Refering back to Wes Ingram's comments, if you're getting bad backfiring your
pump and throttle bodies might need to be adjusted to spec, or something more
substantial has ceased to function on the pump.

>I'm just trying to get a handle on how big this problem is. My cousin
>drove the car from CA to TX for me (moving) and reported that my nicely
>running Spider doesn't run so nicely right now--acting like one cylinder
>doesn't want to fire or is getting fouled. Not sure what it is yet, but he
>seemed impressed by the car overall.

You know the routine here -- check the distro cap, check the spark leads,
check the plugs, lots of ways for sparks to get lost.  I'm a fan of Bosch
Platinum +2 or +4 plugs -- strong spark, foul-resistant.

>Nothing like cruising about 70 mph and getting 28mpg (25mpg on the
>hilly/windy stretches of road). No oil pressure problems (though he says
>he added STP oil treatment to the engine, on top of the 20w50). And, even
>when driving through the desert during the hottest part of the day the
>temp guage barely moved past the 180 mark. Used about a quart of oil for
>450-500 miles of constant driving. Does all that sound on par for a spider
>of this vintage?

You didn't mention the mileage on your engine, but assuming it's not been
rebuilt then that oil consumption doesn't seem out of line for constant
running and hot weather.  When it's really warm, my GTV is the car to drive,
the BMW just can't handle the heat with the stock radiator and fan.  Upgrades
are underway...

Cheers,
Tony
Portland, OR
74 GTV 2000
70 2800CS
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