Fitech Efi Install On 78 Cj5

Discussion in 'Intermediate CJ-5 and CJ-6 Tech' started by Desert Runner, May 18, 2017.

  1. May 18, 2017
    Desert Runner

    Desert Runner Sponsor Sponsor

    Hickory, Pa
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    I have been getting things together to start this conversion. The engine, as it sits now is an AMC 304 Bored .030 over, balanced. Of course that was 28 years, and about 150,000 miles ago. But it still run great and no smoke. I will try to do a compression test before I start just to make sure I don't have any hidden gremlins anywhere.

    [​IMG]

    According to the instructions there are two way to go for supplying fuel.
    1. To use their Command Ctr at $400
    2. Use their rear mounted external fuel pump w/Hoses and fittings for $300

    I opted to combine the two. As was discussed in the Off Topic thread, I am going to use a surge tank.
    The first design used a small 2"x 4" black pipe w/ caps, but I thought maybe that was too small. So I made tank 4"x8" from PVC, used purple cleaner on 1/2" end of pipe and in the cap. put the glue only in the cap, then above the purple on the pipe I put plastic epoxy. Seated the caps and let it sit over night.
    BTW I research the PVC Chemical Resistance chart from ALECO http://www.aleco.com/chemical-chart.html says PVC is "Good" against Gasoline.

    I will take the feed from the mechanical pump and filter, to feed the surge tank thru a one way valve just to make sure it doesn't see any back pressure.
    Note: the fuel system originally had a return line, but I have not been using it for the last 2 yrs, seemingly without any problem. So if pressure does build up and the valve stops flow, this should not be an issue.
    This 5/16ths feed line enters the bottom of the surge tank, on the top there is a 5/16ths return line to the main tank. Then off the other side/bottom there is a 3/8ths line going thru another filter to the electric fuel pump. I have mounted the surge tank and the fuel pump temporarily on the grill brace for two reasons.
    1. limited space/ease of access.
    2. the fuel pump sit right in the air stream coming from the fan. (to help keep it cool)

    Then from the fuel pump to another filter (high pressure capable) to the EFI unit....... Which I will continue with, this weekend. The return line from the Throttle body will go to the top of the surge tank.
    [​IMG]
    [​IMG]

    Jay
     
  2. May 19, 2017
    johneyboy03

    johneyboy03 The green beast

    Quebec, Canada
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    I would be afraid as the mechanical fuel pump is devering around 100 L/ph and they state that they need to a 340 L/ph to feed the efi system.


    Also there is too much connection/fiting on the feed hoze, it can cause cavitation and may bring problem when rolling.

    I did had some problem with the tbi kit because i was having too much connection, i finaly get rid of the problem by putting the minimum fitting possible on the line.

    Also they may have supply some rubber hoze but i would suggest to run hard line (metal or zinc one) and just use rubber when only necessary to make the connection.
     
    Last edited: May 19, 2017
  3. May 19, 2017
    Desert Runner

    Desert Runner Sponsor Sponsor

    Hickory, Pa
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    The flow rate is another reason I went with a larger tank, but since the return line comes back to the surge tank first, the only fuel missing is what went thru the throttle body into the engine, the mechanical pump only has to make up the difference. as for hard line, I have considered it, I am looking for my coil of tubing in the garage, I've found the 1/4" but haven't found the 3/8ths.

    Jay
     
  4. May 19, 2017
    OleBlue

    OleBlue Sponsor Sponsor

    Tennessee
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  5. May 19, 2017
    Oldriginal86

    Oldriginal86 Member

    Pasadena, Md.
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    Looked at the chart and not being a chemist, I didn't see any of the alcohol additives in our fine gasoline today. I hope the pvc works for you. Cool project.
     
  6. May 20, 2017
    zila

    zila I throw poop

    Rock Springs,...
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    Oct 6, 2003
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    I too installed TBI on my 304. I eventually installed an in tank pump. Bought a replacement for a 91 GM and adapted it..
     
  7. May 20, 2017
    Desert Runner

    Desert Runner Sponsor Sponsor

    Hickory, Pa
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    For those who have installed Fuel Injection on your V8's was there a MPG increase? From what to what?

    My 350 1990 GMC Suburban gets 18,
    my 1995 G-20 Van bounces between 13 and 18.
    I'm hoping for 15 or better from the 304.
    I currently get 10 - 11

    Jay
     
  8. May 21, 2017
    zila

    zila I throw poop

    Rock Springs,...
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    Dunno, I don't really keep track as most of my driving is off road in low range 4WD
     
  9. May 22, 2017
    Desert Runner

    Desert Runner Sponsor Sponsor

    Hickory, Pa
    Joined:
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    Did a compression test today, and I am a little surprised. The engine was rebuilt in 1989 at 185,000 it now has 290,000 and the numbers are as follows

    1 150 2 168
    3 150 4 165
    5 150 6 145
    7 165 8 162
    note: the #2 plug electrode was completely worn away with a gap over .050. s/b .035

    I thought I had replaced the plugs last year on my desert run, but they look much older.
    With new plugs the engine purrs again, without a stumble or burble. gotta love maintenance.

    Jay
     
    DrDanteIII likes this.
  10. May 23, 2017 at 8:14 AM
    johneyboy03

    johneyboy03 The green beast

    Quebec, Canada
    Joined:
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    Don't expect a big difference in MPG. Tbi will give a better mix of air/fuel but you won't see any big difference.

    For my 360 i maybe get 1-2 mpg better than carb.
     
  11. May 23, 2017 at 10:00 AM
    timgr

    timgr Jeepin' Nerd Sponsor

    Medford Mass USA
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    Aside from the driver, tuning makes the most difference. It's easier to get a driveable lean mixture with EFI, since you can programmatically adjust the AFR. But theoretically, both a carburetor and EFI should get the same mileage with the same driver under most conditions.

    Megamanual has a lot of stuff about EFI ... Tuning Your MegaSquirt-II™ (or MicroSquirt®)
     

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