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Join Date: Nov 1999
Location: Centerville, Ohio
Posts: 3,120
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More MFI questions, sorry to wear you guys out on this
Ok, well.....it seems that I am not getting batt voltage to the fuel cutoff switch on my MFI 2.2. I have voltage beyond the fuse-box but not up to the switch which leaves the "speed switch" as the only other componant in the circuit. Where can I find this speed switch and what function does it perform.
To satisfy my curiosity, I jumpered 12 v directly from the fuse box to the fuel microswitch and the car suddenly died. Is this what is supposed to happen? Or is it suppoesed to simply idle down a little? Thanks to anyone who can help me out....I appreciate your patience and any tips you can provide.
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Check out my blog for Parts & Cars For Sale - http://renn-spot.blogspot.com/ 1970 911S, 10 sec 67 Beetle (300 rear wheel HP) RGruppe#252 |
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09-05-2002, 12:32 PM
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Moderator
Join Date: Dec 2001
Posts: 9,569
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Speed Switch
Warren Hall has written extensively on this, do a search on MFI speed switch and all will be revealed. He actually reverse-engineered the switch and posted a circuit diagram. . .
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'66 911 #304065 Irischgruen ‘96 993 Carrera 2 Polarsilber '81 R65 Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13) Ex-'88 Carrera (Sold 3/29/02) Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04) Ex-'89 944 Turbo S (Sold 8/21/20) |
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09-05-2002, 02:47 PM
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Join Date: Jan 2002
Location: West Lafayette Indiana
Posts: 1,421
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Darn engineers
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Dennis H. 72 911E 2.7 RS stuff 72 911T with a 2.7(Sold 5-13-2011) 2012 Kona Blue Metallic Mustang GT Convertible 6spd 67 Mustang coupe future SVRA group 6 car 63 Falcon hardtop 302/4spd |
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09-05-2002, 03:24 PM
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Join Date: Nov 2001
Location: New York, NY
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It's a fuel cut, I think it should kill your engine. If the rpm transducer is functioning properly, then it will cut the 12v signal once RPM has dropped below a certain point. Warren has posted a bunch of stuff on the RPM transducer, as well as others who have posted how to fix them. Apparently the components inside corrode and break under vibration. It's a relatively simple circuit, and shouldn't be too hard to restore - or you can spring for a new one, cost in the low $200's
 Brad
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73 911S Coupe sold |
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09-05-2002, 06:05 PM
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Join Date: Apr 2001
Location: Linn County, Oregon
Posts: 48,576
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Now, to see if I can type it all. Check out:
http:www.pelicanparts.com/ultimate/Forum3/HTML/012702.html Warren's words... |
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09-05-2002, 06:11 PM
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Join Date: May 2002
Location: Chews Landing, New Jersey
Posts: 272
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Hi
Warren help me with my idle/speed switch poblem, maybe I can pass on the favor, The speed swict is the aluminum box just to the rear of CDI. Terminal #2 is 12v, #3 is ground, # 4 is the imput from points and #1 is a 12v output when your rpm is above 1300, which passes through the micro switch (when it's closed) to the fuel cut off sol. Search "idle " and "jeff m" it was quite a recent post and Warrens excellent diagrams are there, good luck Jeff |
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09-05-2002, 06:21 PM
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Join Date: Nov 1999
Location: Centerville, Ohio
Posts: 3,120
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I have been reading some of the old links that Warren P.M.'d to me. I have a much greater understanding now. Talked to my older sisters husband earlier today. He was an electronics whiz back in the 70s (pre computer) and he is confident that with his old equipment and warren's schematics that we can repair my speed switch. In fact, if this works out maybe we can provide a inexpensive alternative for people like me that read warrens tech info and get totally boggled
 . I just want to say thanks again for all the people who have been helping me out with these problems. Im sure you have answered these questions before. I appreciate your generosity. Dave C
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Check out my blog for Parts & Cars For Sale - http://renn-spot.blogspot.com/ 1970 911S, 10 sec 67 Beetle (300 rear wheel HP) RGruppe#252 |
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09-05-2002, 06:22 PM
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