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Discussion Starter #1
Hey guys,
Ya'll seem to be the right knowledge resource for my '74 Spider.

We have a problem with the fuel shutoff solenoid controller microswitch. It is stuck on all the time which means no fuel! No run. So we unplugged it and then of course we get fuel and the car runs but then it will of course backfire under deceleration because now it won't shut the fuel off when it is specifically supposed to.

What to do? The easiest solution is to yank the wire and that's what many people did for many years.

Or replace the microswitch? Where to get one? My mechanic is having a hard time sourcing one plus he isn't dying to take the whole Spica FI off (again). It just got totally rebuilt by Wes a few months ago, but I guess not this silly microswitch.

The more advanced question is has anyone ever built a little retro fit electronic control for this function reads the rpms off the distributor and does this job electronically instead of mechanically (control the fuel pump).

Thanks in advance for your suggestions.
 

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Hmmmmmm . . . . That's really unusual that a pump from Wes would have a bad microswitch, but it's' probably the "lightbulb" theory . . . . one day you turn it one and it doesn't work.

First, the microswitch is not essential to the operation of the pump. There is also an internal mechanical cutoff. Actually, it's a specific position on the 3D cam when the engine is running above 1300 rpm. In fact, my '74 SPIDER's SPICA pump has a shorted microswitch right now. I've simply remove the electrical connector from the Fuel Cutoff Solenoid and relied on the internal cutoff. Works fine with no backfiring. When I get some time, I'll remove the pump and replace the microswitch. The microswitch is available through International Auto Parts (www.international-auto.com) and several other vendors for about $60. That kind of money for a simple and (very) little switch is pretty steep but it's the only one that I know of that fits.

If you're engine is still backfiring after deactivating the Fuel Cutoff Solenoid, it's likely that your throttle manifold butterfiles are out of adjustment and slightly open at the idle stop. At idle, the throttle butterflies should be fully closed and the only air delivered to the manifold should come throught the idle system. In addition, it's likely that the rods are holding the FI pump throttle lever open slightly causing the stylus to never get into the fuel cutoff portion of 3D cam and continue to deliver fuel during what you "think" is throttle closed decel. (sorry about the run-on sentence).

In fact, if the microswitch fails open, it's likely you'll never know it. If it shorts (like mine) and delivers a continuous fuel cutoff signal, then the engine dies and will not restart. Simply pulling the wire off the FCS fixes the no start/no run condition immediately.

It is also possible that the adjustment on the microswitch is not quite right, but I'm sure Wes calibrated the pump correctly before he sent it to you. I would definately drop him an email or phone call. I'm sure he can source a microswitch.

Regardless if you need to R & R the microswitch and/or adjust it, it's going to require a R & R on the pump. It's a bit of a PITA, but not really complicated.

Never heard of anyone fabricating a distributor driven cutoff switch. That'd cost a lot more than a $60 switch.

Drop me a PM if you'd like more info.

Here's a couple of links that may be of interest to you:

http://www.alfaclub.org/techstff/spica.htm

http://www.alfaclub.org/techstff/tunespca.htm
 

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Discussion Starter #3
Wow thanks for the fast reply Roadtrip. Your Spider is the same year and color as mine. I had a feeling you would be the first to reply. Thank you so much. I'll pass this info along to my mechanic.
 
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