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Technical Edelbrock Carb Mechanical Fuel pump assistance needed

Discussion in 'The Hokey Ass Message Board' started by Dirk35, Jun 2, 2019.

  1. Dirk35
    Joined: Mar 8, 2001
    Posts: 1,995


    Hi all. I am hoping that you all can give me so ideas on how to fix a couple of issues with my carburetor.

    What I have is a 1949 Ford PU on a 1975 Mercury car frame (lets not get into the details of better frame swaps, it was free). I put a 390 FE with a C6 in it. It has a Edlebrock 1405 4 barrel carb which I rebuilt and uses a mechanical fuel pump. It has a Russell online fuel filter and aluminum 3/8"s line along the frame with a barbed adapter to connect each end with rubber fuel line at the tank and from the front of the frame to the fuel pump. I used a 1988 Jeep Cherokee gas tank and ran the fuel pick-up from the pick-up line of the in-tank fuel sender. It doesn't have the original electric pump in the tank, the return line is capped off.





    I have two problems:

    1. After sitting for more than a few hours, It drains the fuel back out of the carb and I have to prime the carb every time to get it to start. If I don't prime the carb, it'll crank until the battery goes dead. However, just a little fuel poured down the carb (like 1-2 shot glasses worth) is all it takes and it'll start right up and keep running as if the fuel was always in the lines. It doesn't really cough and sputter (as if trying to shuck up the fuel from the line all the way from the tank) after priming it, just starts right up. Any suggestions?

    2. The fast idle cam and choke doesn't work properly. I have to manually pull the fast idle cam and lever up to get it to idle until it warms up. Once it warms up (even on a hot day), I have to open the hood and release the fast idle cam or it'll idle way too high. Is there something that is supposed to automatically set this to the correct position so I do t have to do it by hand? It has an electric choke and it's getting 13.56 volts to the choke.



    Sent from my iPhone using H.A.M.B.
  2. jimmy six
    Joined: Mar 21, 2006
    Posts: 5,204

    jimmy six

    From all the experience I've had (I'm 74) fuel does not drain out of a carb up thru it's needle and seat, into the fuel line, to the fuel pump, and back to the tank. I would start with the float levels. Yes after a time, 2 to 3 weeks, todays fuel evaporates.

    Next turn the electric choke unit with the throttle partially open until the choke butterfly is at least 3/4 closed. The link on the fast idle should move enough so that the fast idle adjustment screw is up on it. All the carbs I have do have an idle adjustment screw that has nothing to do with the fast idle adjustment screw. As the electric choke heats up the fast idle arm will fall away and the carb will then main butterflys(throttle plates) will be near closed with the true idle adjustment crew holds it at where you want it in gear if you have an automatic trans.

    All links and arms should be very free with no "sticking" possible.

    No fuel should ever leave a fuel pump diaphram. If you decide to use a hard line from the fuel pump to the carb install a glass bowl fuel filter. Even after 2-3 weeks mine always has fuel in it. I may need to cranks over my engine for 10-15 seconds before pumping the throttle twice to set the choke fast idle but even after a month it starts right up. good luck
    Truck64 and upspirate like this.
  3. You need a 1/4" -1/2" phenolic carb spacer under the carb to keep the fuel from boiling after you shut her off. Your problem is the fuel bowl drying up from hot soak evaporation. Edelbrocks are known for that.
  4. BadgeZ28
    Joined: Oct 28, 2009
    Posts: 1,012

    from Oregon

    Two common problems with the Carter-Edelbrock cabs are heat soak as mentioned and sensitivity to fuel pressure. Best to keep pressure around 5 psi. 6 is usually considered a max. I have had to install a inline pressure regulator.
    upspirate and Montana1 like this.
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  5. B.A.KING
    Joined: Apr 6, 2005
    Posts: 3,554


    Summitt sells a plastic spacer, 20 bucks i think.May need longer carb studs.I run 4 pounds. Not saying the other is wrong .just what i use.
    Truck64 likes this.
  6. flux capacitor
    Joined: Sep 18, 2014
    Posts: 659

    flux capacitor

    Edelbrock no longer makes one of their earlier fixes ..... fuel filter #8873 which contained a wix 33052 Quadra jet check valve filter. Used 3 over years on various rides & fixed them all. When placed between pump & carb . Might find a used one n just pop in s new cheapo filter . Flux
  7. JeffB2
    Joined: Dec 18, 2006
    Posts: 7,812

    from Phoenix,AZ

  8. karl share
    Joined: Nov 5, 2015
    Posts: 81

    karl share

    Loosen the 3 little screws on the elec choke housing, hold throttle open and then turn the black plastic housing either way, you will see the choke butterfly starting to close, as mentioned before only let it close about 3/4 . then tighten screws. Also with the air cleaner off pump the throttle and see if it is squirting in any fuel, because if your accelerator pump is shot that will cause hard starting issues. :)
  9. Dirk35
    Joined: Mar 8, 2001
    Posts: 1,995


    I'm pretty sure I have a 1/2 aluminum spacer under it currently. Would the plastic spacer make that much difference in the heat transfer?
  10. rustydusty
    Joined: Apr 19, 2010
    Posts: 1,260


    Aluminum, the same material your manifold is made out of, is a heat conductor. Ever grind a piece of aluminum? It gets extremely hot...
    I would opt for the phenolic resin spacer as suggested previously.
    olscrounger and Montana1 like this.
  11. Dirk35
    Joined: Mar 8, 2001
    Posts: 1,995


    Oh, I'm definitely putting the plastic spacer on it, already ordered it from JEGS. I guess I should've worded my question better. I was just curious that with the gasket on each side of the aluminum spacer, if it really transfers heat that much compared to the plastic spacer, or do the gaskets not really limit the transfer of heat.

    I'm also going to take the carb back apart and see what's going on with the accelerator pump.
    Montana1 likes this.
  12. You don't have to take the carb apart to fix your accelerator pump unless it stopped up with junk. The only thing to be very very careful about is that tiny little clip because it's easy to drop and lose. Use a set of needle nose and grasp it very well before you pull it off.
    olscrounger likes this.
  13. Dirk35
    Joined: Mar 8, 2001
    Posts: 1,995


    Just a follow up:
    I replaced the Aluminum Spacer with a plastic spacer. Ive re-adjusted the electric choke per the above instruction.

    After I re-set the choke, It is now doing better at keeping idling, but I have to manually set the fast idle still. But it is now at least holding the fast idle after I manually set it and it is taking les time to warm up and run on its own (Perhaps 3-5 minutes).

    If I start it after a day or two, it starts right up, but still wont idle without me manually setting the fast idle by hand. I have to do this even if it sits for a couple of hours.

    If I let it sit for more than 3-4 days without starting it, it will just crank and crank and never start until I pull off the air breather and prime it by dumping a bit of fuel down the carb. I let it sit for two weeks this time, then I checked and it sprayed a little bit of fuel from the pump jet, but it was only like two little squirts worth, and wasn't enough to start it.
    Last edited: Sep 5, 2019
  14. Truck64
    Joined: Oct 18, 2015
    Posts: 3,866

    from Ioway

    What's the backstory on the 390? Good compression, good timing, hot ignition?
  15. Dirk35
    Joined: Mar 8, 2001
    Posts: 1,995


    Truck64 might be onto something here. I built the engine in 1987 and drove it through High School and 1st couple of years of college. Then it sat in my parents pasture for about 10 years. Then I pulled it, cleaned up the outside, had the transmission rebuilt, and built this pickup around it. So it is definitely in need of a rebuild.

    But once it warms up, it starts back up and runs just fine, and will do so for a couple of days. But after it sitting about day 3, it needs me to manually prime it to get it to start. After it cools down (a few hours of sitting in the parking lot at work, I have to manually set the fast idle).
    Last edited: Sep 6, 2019
  16. olscrounger
    Joined: Feb 23, 2008
    Posts: 3,576


    Plastic spacer is a big plus. I also have an elec pump by the tank with a button under dash to prime after it sits a bit-then runs thru regular pump. Only need it if car sits for a couple of weeks to prime it.
    pprather and '49 Ford Coupe like this.
    Joined: Mar 21, 2014
    Posts: 529

    from okc

    Sons Datsun z did that, with new hoses even, tightened the clamps, fixed it..
  18. Mr T body
    Joined: Nov 2, 2005
    Posts: 2,083

    Mr T body
    Alliance Vendor
    from SoCal

    Next time it has sat for long enough to create the problem, pull the air cleaner, open the choke and pump the throttle. If you have a pump shot, fuel isn't your issue. While the carb SHOULDN'T drain, what would concern me more is the pump not delivering enough in a few seconds of cranking to start the engine (or make it sputter). It could be the check valves in the fuel pump are bad allowing the fuel in the line to drain back (though this can't siphon fuel out of the carb bowl).
    Did you pull the sender out and make sure the fuel line extends all the way down to the "pot" in the bottom of the tank?
  19. 6sally6
    Joined: Feb 16, 2014
    Posts: 903


    Disconnect that electric choke! Never had one worth a hoot. That fixes half your problem right there.
    Montana1 likes this.
  20. pprather
    Joined: Jan 10, 2007
    Posts: 1,557


    I'd try some carb cleaner spray on the fast idle linkage. That may loosen it up, assuming it was assembled correctly.

  21. Is the tank properly vented? :confused:
  22. Dirk35
    Joined: Mar 8, 2001
    Posts: 1,995


    Tank is properly vented. I just replaced the vents in the tank (there are two of them for some reason) earlier this year.
  23. It is still unclear if your carb bowl has gone dry on you after sitting awhile. You said that pumping the throttle only gives a pittance of a squirt. Either your carb is dry or your accelerator pump is shot. Have you pulled it out to see if something is wrong with it? Fifteen seconds of cranking should fill the bowl.

    As Pointed out above,, pull the air cleaner, Give the throttle full stroke, and count how many times it takes to stop pumping. Then give it a crack for 5 seconds and see if you got fuel. And do that over and over again. Maybe you've got a worn out fuel pump. As for the comment about the electric choke I'm sorry but that's BS. Adjust the choke so that it's just touching the close position when it's cold. Report back.

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