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  1. #1
    4 PSI Boost
    Join Date
    Jul 2020
    Location
    Little Falls MN
    Posts
    6

    1984 fuel pump/pressure questions

    I have a 1984 Svo with an 86 engine, brown tops and a PE computer. It has a Kirban adjustable fuel pressure regulator only 200 miles on it) and a Bosch N69100 inline pump (200 miles) and a new filter next to the pump. Factory in tank pump as far as I know. With the engine off using the eec test connector running the fuel pumps, I can only get 50 psi. If I turn the pressure up using the adjustable regulator, it will only go up to 50 psi. If I set the base fuel pressure to 40 psi and add air pressure to the boost reference line on the regulator, the pressure will climb to 50 psi @ 10 psi of air but will not climb with more air pressure. I have ordered a Walbro GSS342 and a fuel sending unit/pump hanger for it.

    I have two questions

    1: Am I overlooking something? I feel like the pump should have no problem going up to 70-80 psi.

    2: Why do people remove the exterior pump? It is new and from what I have read, is better than the walbro pump?

    Thank you.

  2. #2
    OVER-BOOST!! svono50's Avatar
    Join Date
    Apr 2002
    Location
    Streamwood, IL
    Posts
    4,096
    SVO's: 86 1C
    I am sure someone with hands on experience will chime in, but I believe the 84's had a resistance wire feed to the in-tank pump, but I am not sure if the external pump was also electronically throttled back in any way. Most folks move to the in-tank setup to simplify the fuel pump system and go with a high volume in-tank pump. Is it 'better'? I can't really say, as I have only owned my 86 with the in-tank setup. In any case, your system should push more than 50 psi. I run a Kirban on my 86 and have no issues pushing >50 psi, along with a 1:1 ratio beyond 50 psi. Have you pinched off the return line to the tank to see if you can spike the number above 50?
    Ted
    86 SVO Mustang
    17 Cooper S Clubman ALL4

  3. #3
    Administrator SVOeric's Avatar
    Join Date
    Mar 2002
    Location
    Richmond, KY
    Posts
    12,982
    SVO's: 86-1C & 86-1E
    one of your pumps has failed.. (or even the filter inside the tank) I'm not familiar with that Bosch part number. it's possible it's not capable of reaching the pressure @ volume needed.

    The only other thing to try is clamping off the return line, and seeing if your pressure goes higher. My kirban is 10 years old and handles 80 psi very well.
    BE CAREFUL doing this -- use short bursts on the pump, if it does go higher, stuff could go *POP* with flammable liquid, that can be VERY bad.

    ONE high pressure pump in the tank is the way to go. Replace the in-line filter with another filter, or some custom made connector... (not clamps and rubber hose)
    Eric C
    SVOCA Webmaster

  4. #4
    OVER-BOOST!! Erics SVO's Avatar
    Join Date
    Jul 2003
    Location
    Baltimore, Maryland
    Posts
    2,842
    SVO's: 85 1C, 85.5 1B
    IIRC the filter for said replacement is from a Ranger, it has longer tubes on it to be able to hook up the lines once the external pump is removed. Remember to take care of the resistance wire in the hatch area harness.
    -Eric
    85 1C, 85.5 1B
    10 GT Premium
    01 Jeep Wrangler

  5. #5
    4 PSI Boost
    Join Date
    Jul 2020
    Location
    Little Falls MN
    Posts
    6
    I installed a 255 in-tank pump and removed the inline pump. This 100% solved my fuel issue, now onto the other issues. Thank you.

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