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Thread: Fuel System Questions

  
  1. #1
    6 PSI Boost
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    Fuel System Questions

    Hi,

    I'm replacing the fuel level sending unit and the rusty fuel tank on my 84 SVO. While I have the tank down I also want to replace the fuel pump. Any suggestions on which pump to use. Should I just use a pump for an 84? Is there any benefit to using an 86 pump or an aftermarket pump like a Walbro? I'm not planning on doing any major engine upgrades although a previous owner installed an 85/86 turbo.

    Fuel injection is new to me so I also have a question on injectors. My car has Siemens Deka single hole injectors with gray tops. The numbers molded into the plastic tops appear to be 1976 and 7895. Is this a good choice for injectors or are there better options?

    Thanks in advance for any suggestions!

  2. #2
    OVER-BOOST!! svono50's Avatar
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    Hmm, sounds like the PO did some 'tinkering' with the car, so I think you need to do some more research before doing much more work. The turbo was changed likely to get a water cooled center section, as the 84 units were known to cook themselves. I don't know anything about those injectors, other than a quick 2 minute read on a Google search. They appear to be a 'premium' priced unit, so could also be a nice unit. Only issue is I don't see a 30 lb/hr unit listed, so you may have oversized injectors in there. You may want to contact a Deka seller/distributor to confirm the injectors you have are appropriate for your 84.

    On the fuel pump front, it is really up to you whether or not to change over to the single-pump style (i.e.- 85.5-86) setup or keep the dual-pump setup you have now. If you really don't plan on pushing up the HP, then I would suggest keeping the dual-pump setup. If you think you may want to up your HP, then going over to the single-pump (i.e.- in-tank) would be prudent at this time with the tank out. The main advantage to going with the in-tank only setup is there is one less pump to worry about and you can also get larger capacity in-tank pumps as well. Although there are folks that have been able to get decent numbers out of the dual setup as well.

    Do some more research and ask yourself what your longer-term goals are for the car to help you pick a path. Good luck.
    Ted
    86 SVO Mustang
    17 Cooper S Clubman ALL4

  3. #3
    6 PSI Boost
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    Thanks for the info. I decided to stay with the twin pump set-up. I have some more questions.
    1. I read in another post there should be a ground wire connected to the turbo. Where is the other end of the ground supposed to be connected?
    2. Where is the ground wire from the bell housing supposed to be connected?
    3. My car has a regular PCV. I bought the recommended Motorcraft PCV. Is the second small nipple supposed to be connected to anything or just capped off?
    4. Should the breather on the valve cover be connected to the intake piping?

  4. #4
    OVER-BOOST!! GAboySVO's Avatar
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    Quote Originally Posted by RFP811 View Post
    I have some more questions.
    1. I read in another post there should be a ground wire connected to the turbo. Where is the other end of the ground supposed to be connected?
    2. Where is the ground wire from the bell housing supposed to be connected?
    3. My car has a regular PCV. I bought the recommended Motorcraft PCV. Is the second small nipple supposed to be connected to anything or just capped off?
    4. Should the breather on the valve cover be connected to the intake piping?
    The turbo orange ground wire mounts to one of the bolts holding the snout on the turbo compressor housing.

    The bell housing ground strap connects to the firewall just to the right of the heater lines near the trans tunnel

    Our cars don't use the plastic nipple that comes with the part. You can remove it or cap off the other port if it is already installed.

    Valve cover breather in the stock setup is connected to the compressor housing snout. This is a closed PCV system and the compressor evacuates the oil vapors and crankcase pressure via the valve cover. The down side of this system is that eventually you will get oil in the intake track and the oil vapors have the effect of lower the octane rating of your air/fuel mixture.
    Mike S

    '86 SVO 9L Leather
    '86 SVO 9L Road Warrior
    '96 300ZXTT

  5. #5
    6 PSI Boost
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    My car is missing the turbo ground wire. Is the other end of the turbo ground wire supposed to be in the wiring harness or does the ground wire connect to the unibody?

    Are there sources and P/N's for the PCV hoses? The local Ford dealer and Autozone parts house couldn't find any P/N's.

    Thanks for any info!

  6. #6
    OVER-BOOST!! GAboySVO's Avatar
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    Quote Originally Posted by RFP811 View Post
    My car is missing the turbo ground wire. Is the other end of the turbo ground wire supposed to be in the wiring harness or does the ground wire connect to the unibody?

    Are there sources and P/N's for the PCV hoses? The local Ford dealer and Autozone parts house couldn't find any P/N's.

    Thanks for any info!
    I believe the orange ground wire goes to the ECU and is part of the harness that includes the BAP sensor.

    For the PVC hose, I think you will need to find a generic 90* elbow with the correct ID and length.
    Mike S

    '86 SVO 9L Leather
    '86 SVO 9L Road Warrior
    '96 300ZXTT

  7. #7
    6 PSI Boost
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    Thanks for the info. I found the turbo ground wire connected to one of the mounting screws for the turbo boost control module.

  8. #8
    OVER-BOOST!! GAboySVO's Avatar
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    Quote Originally Posted by RFP811 View Post
    Thanks for the info. I found the turbo ground wire connected to one of the mounting screws for the turbo boost control module.
    You need to move this to the turbo. Use one of the bolts that holds the compressor housing to the center section.
    Mike S

    '86 SVO 9L Leather
    '86 SVO 9L Road Warrior
    '96 300ZXTT

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