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Thread: Replacing 1986 F-150 EFI System

  1. #1

    Default Replacing 1986 F-150 EFI System

    I recently rebuild my truck and have the 1986 EFI 5.0L EFI system in it. It has the surging idle issue that I simply can't seem to get around no matter what I replace. I want to replace the entire system with the Sniper EFI. Does anyone know what I need to get for this project? I already know i need to get a 4 barrel intake, that's a given. But what else do I need for this change, as I don't have a carb in the truck to start with.

  2. #2
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    The Sniper EFI instruction manual answers these questions.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  3. #3

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    After downloading a few of the online manuals, I now know what I need to get before purchasing the Sniper EFI Kit.

  4. #4

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    Another question. My truck currently has two fuel pumps. One in the tank to push to the HP pump on the frame. The pump on the frame will of course not produce the pressure that the Sniper EFI system wants, so I know I have to replace that one. My question is, can I still keep the pump in the tank working like it does? Or, do I need to remove it?

  5. #5
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    The Sniper EFI only needs one EFI fuel pump. Electric fuel pumps produce volume, not pressure. The fuel pressure regulator creates the pressure.
    http://documents.holley.com/199r11031r.pdf (Holley Sniper EFI Instruction Manual - "Fuel Pump & Filter Installation", Pages 4-6)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  6. #6

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    OK, let me be a little more precise in what I'm trying to figure out.

    On my truck, which is currently a factory EFI 5.0L system, I have a pump in the tank that's part of the sending unit, and also a pump on the frame. If I can't keep the pump in the tank, then I will have to find a way to modify my sending unit, as the tank pickup screen is mounted to the bottom of the in-tank pump. I just need to know if keeping the pump in the tank will affect the operation of the new pump, that will be coming with the Sniper EFI system. I fully understand how fuel pressure is created. I'm also only asking this as I can't find actual documentation on converting from my current EFI system to the Sniper EFI system, as I already have a lot to try to figure out due to having to change my entire ignition system, as it's all currently controlled by the ECM.

  7. #7
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    Quote Originally Posted by spaceace View Post
    I just need to know if keeping the pump in the tank will affect the operation of the new pump, that will be coming with the Sniper EFI system.
    I don't understand why you even need the Sniper fuel pump. You already have an in-tank EFI fuel pump (& sock filter). That should be all you need. You don't need two fuel pumps.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  8. #8

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    In 1986, when Ford put the EFI system into the trucks, they used a pump in the tank that's just for volume at low pressure to push the fuel to the high pressure pump that is mounted on the frame. The pump in the tank is far too small to be able to build the kind of pressure needed for the Sniper EFI system. Also, the HP frame pump only runs the pressure at around 35 psi. Why they put two pumps on the trucks, I have no idea. I also have no clue if the factory HP pump on my truck will be able to produce up to 60 psi that the Sniper EFI system needs. I have to drive my truck everyday, so I can't experiment with the HP fuel pump to see if it will build up to 60 psi, as I don't think the plastic lines would hold that kind of pressure as they are all from 1986. LOL.

    Here's the tank pump: https://www.carid.com/1986-ford-f-15...250875705.html

    And the frame pump: https://www.carid.com/motorcraft/fue...743&url=812029

    UPDATE: After a lot of research, I finally got the specs on my fuel pump. It maxes out at 70 psi, but will only put out 60 for a short time before being overloaded. So, it has to be replaced and the in-tank pump is still fine where it is to push fuel to the HP pump when I get it. I'm going to try to find a dyno in my area to test the truck on before & after I change to the Sniper system, just to see what the change will be.

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