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Thread: Need some help

  
  1. #1
    4 PSI Boost
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    Need some help

    Hi, newbie here. I am posting a picture of a vacuum switch on my 1986 SVO. My understanding is it reduces the voltage to the fuel pump when vacuum increases. My question is, I have a hole in the black rubber "condom" portion of it. Will this cause a vacuum leak or affect the way the switch works in any way? And secondly does anyone know where I can get a replacement? Thank you in advance
    Attached Thumbnails Attached Thumbnails DSC_7544[1].jpg  

  2. #2
    OVER-BOOST!! gbeaird's Avatar
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    SVO's: '86 2R
    I'd have to go have a real close look, but I think the cover is just that, a cover, meant to simply protect the switch and the connections from moisture. Probably an issue, since it's so close to the trailing edge of the hood.

    I can't offer anything for info on replacements. Sorry.
    Gene Beaird,
    86 2R SVO, G Stock,
    Pearland, Texas

  3. #3
    OVER-BOOST!! svono50's Avatar
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    SVO's: 86 1C
    Correct, its purpose is to lower the voltage to the pump to make the pump 'quieter' at idle conditions for NVH, from what I have been told in the past. Since our model was targeted against the Euro cars of the time, that certainly could have been the case. It triggers at ~5" vacuum from closed to open to switch the pump power circuit.

    That is simply a rubber cover over the pressure switch and won't create any leaks. The vacuum line goes onto the nipple and the electrical connector is covered by the boot, nothing fancy. You can snip the tie wrap on the one end and pull back the cover to make sure there isn't any water trapped in there and to make sure the contacts are clean on the switch and harness connector.

    I just went through a project last fall trying to figure out a fuel pressure problem and found that my switch was malfunctioning. I think this is the same issue that cropped up a few years ago at a Reunion and caused me to swap out my fuel pump. I have a strong suspicion that it was this switch and not the pump!! I actually did a little video on my testing to show how/what happens if your fuel pump stays at 9V and doesn't get a full 12V like it should here:

    https://youtu.be/PpEu1zkEurE

    I actually found an OEM replacement pressure switch out on the interwebs, somehow. I kind of feel like I hit the lottery, as I am sure this is one of the most obscure components on our SVO's. If you suspect yours is non-operative, you can simply remove the switch, put a jumper across the connector pins, cap off the pressure tap for the switch and call it a day...leaving your pump circuit up at 12V all the time.
    Ted
    86 SVO Mustang
    17 Cooper S Clubman ALL4

  4. #4
    OVER-BOOST!! svono50's Avatar
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    SVO's: 86 1C
    Quick follow up from my home base. The pressure switch was actually made by GE, yep, first time I have ever seen their logo on an automotive component outside of a light bulb. The switch is actually adjustable by a set screw that is down between the electrical terminals. I played with my stock switch adjustment, but no matter what I did it wouldn't consistently make full contact when closed as measured by the resistance across the terminals. The switch is normally closed and is opened when it sees that 5" of vacuum.

    The part number of the switch is E5ZZ-9C408-A and is labeled as "switch".

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    Ted
    86 SVO Mustang
    17 Cooper S Clubman ALL4

  5. #5
    4 PSI Boost
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    need some help

    Quote Originally Posted by svono50 View Post
    Quick follow up from my home base. The pressure switch was actually made by GE, yep, first time I have ever seen their logo on an automotive component outside of a light bulb. The switch is actually adjustable by a set screw that is down between the electrical terminals. I played with my stock switch adjustment, but no matter what I did it wouldn't consistently make full contact when closed as measured by the resistance across the terminals. The switch is normally closed and is opened when it sees that 5" of vacuum.

    The part number of the switch is E5ZZ-9C408-A and is labeled as "switch".

    Click image for larger version. 

Name:	Switch - Ford_E5ZZ-9C408-A_01.jpg 
Views:	3 
Size:	124.9 KB 
ID:	47550 Click image for larger version. 

Name:	Switch - Ford_E5ZZ-9C408-A_02.jpg 
Views:	3 
Size:	76.0 KB 
ID:	47551 Click image for larger version. 

Name:	Switch - Ford_E5ZZ-9C408-A_04.jpg 
Views:	3 
Size:	78.9 KB 
ID:	47552 Click image for larger version. 

Name:	Switch - Ford_E5ZZ-9C408-A_07.jpg 
Views:	3 
Size:	68.4 KB 
ID:	47553
    Thanks everyone. That is exactly what I needed. Mark in San Diego.

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