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HEI problem

Discussion in '40- & 55-Series Tech' started by mhdsummers, Jul 28, 2005.

  1. mhdsummers

    mhdsummers

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    78 FJ40 2F, HEI

    Symptons:
    Runs fine for long periods of time. I shut off the motor after a long haul and then restart. Idles fine. Then after about 100 yards the motor just dies. Sometimes I can get it to come back to life before I roll to a stop and then it will try to stall again. After the second time trying to stall, it runs fine for a long time again. When it stalls, there is fuel in the carb.
    After a couple of weeks of this, it wont start at all so I took the ignition module in to napa and they said it was fine. I bought another one just in case and installed the new one with the grease provided. Everything was back to normal for a while then it started doing it again. I replace the new module with the old one and everything was fine for a while again.

    Plugs are gapped to .045

    I was thinking new plugs, ignition wires. Any other suggestions? This seems like a wiring problem of some kind. Sometimes, I can just take the cap off the distributor and put it back on and the engine fires right back up.
    Thanks.
     
  2. peesalot

    peesalot

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    You may have issues with the gear or the shaft of the Dist. Replace the coil it sound like it may have a short that burns itself free until it gets hot then contacts , arcs , and is free again for awhile.
     
  3. dfmorse

    dfmorse

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    MHD; is this a Man-A-Fre unit? Do u have the original distributor & wires? What high voltage wires are u using? How long has HEI been in service?

    This sound like a fuel problem. How many miles on FJ40? Check fuel filter. My '79 does just what yours does when the filter is somewhat clogged.

    Can u go back to original distributor and coil?

    Keep us posted...
    dfm
     
  4. andrewfarmer

    andrewfarmer

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    I had a proble like this was the coil shorting out - went through several coils.

    Make sure the coil has the metal 'earth' connector screwed to it - this solved my problems.
     
  5. elblat

    elblat

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    mos def check the coil... This exact thing happened to me (although not an HEI unit), my guess is that the coil would get hot and malfunction, bad connection inside. New coil fixed it.
     
  6. dfmorse

    dfmorse

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    What good is this gadget if the dam coil overheats?
     
  7. mhdsummers

    mhdsummers

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    This is a GM unit from Classic Cruisers in Colorado.
    I will try replacing the coil. If that works I will try to figure out why it went bad so quickly. I have only had the HEI for about 2000 miles. It was working flawlessly for the first 1500 miles.

    I can get it to fail quite easily now. The last time it failed, I had the pedal to the floor and I kept it there for some time after the motor began to die. I turned the key off quickly and check the fuel level in the carb and it was right on the money. There was a smell of raw fuel so I am pretty sure it is a spark problem.

    Thanks for all your quick replies. I will let you know how the new coil works.
     
  8. mhdsummers

    mhdsummers

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    So I just replaced the coil and it seems to have fixed my problem. I wonder why it only lasted ~2000 miles? Maybe it is overheating since the HEI distriutor sits very close to the block. I wonder if a heat sheild would help.

    When I first put the HEI in, I thought I gapped the plugs to .045 just like eveyone suggested. However, when I checked the gap 2 months later, they were way off. I think they were about .065 or more. This may have been the reason my coil went bad. I put another 1000 miles on after I fixed the gap without any problems. I only wheel my LC (and fix it) :)
     
  9. mhdsummers

    mhdsummers

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    OK, the coil was not the problem. I thought it had worked but the next time I went for a drive the same thing happened again.

    I guess it could be a fuel problem of some kind. Maybe its flooding. There is always fuel in the carb, right in the middle of the glass.
    How do I set something up so I can see if I have spark when the problem happens? I can usually restart after it stalls as long as I do not use the choke and keep my foot off the gas. It really seems to be flooded.


    Strange thing is, once it happens a couple of times, I can then drive for a long time. It only seems to happen after I shut the motor off and try to restart 5-10 minutes later. Then it will stall twice, and then be fine until I shut off the motor again.

    I am open to any more suggestions.
    Thanks.
     
  10. Otterav

    Otterav

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    Hey,
    Try closing the plug gap down to .032. The increased gap my be causing the coil to break down. I had the same issue with my '40, the p/o wired the external ballast resistor req'd coil to 12v continuous duty, when it got hot it would sputter and stall usually when I stepped on the gas(accel pump activitated). Replaced the coil with a Pertronix flamethrower, problem solved.
    Otter :cool:
     
  11. mhdsummers

    mhdsummers

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    My problem might be flooding. When it stalls, I smell gas. It is also hard to start after this happens and it will only start if I have my foot off the gas and the choke closed. If I hit the gas or pull the choke out, it will not start.

    I thought that if the float level was correct, flooding should not be a problem. Is that true? I have been know to be wrong one other time :)
    Can anyone tell me what I can do to determine if my problem is flooding?

    Thanks.
     
  12. ranger

    ranger

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    I had the exact problem in a 72 chevy P/U that I swapped out the points dist for an HEI. It would idle dine all day, but once I got in and started to drive, 100 yard it would just die. Start it up again and the samething would happen. I troubleshot it down to the ignition module. Canged that part and problem was solved.
     
  13. peesalot

    peesalot

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    o.k.
    close plug gap

    make sure accell. pump is not stuck or letting gas get sucked by it .

    make sure coil & ign. are wired right as in the coil will burn up and ign. module to if power is fed to them when eng. is off.


    double check firing order and timing.

    your ignition problem may be causing the fuel not to get burned thereby simulating a carb problem.......
     
  14. Pin_Head

    Pin_Head

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    It doesn't sound like an ignhition problem anyway, it sounds like a fuel problem wiht flooding. Shine a flashlight down into the manifold with the throttle open after you have shut it down for a few hours and see if you have a pool of gas.

    If it smells like gas, you see gas and it acts like it is flooded....


    It is not an ignition problem.



    If gas drips out, chances out it is siphoning out of the idle circuit, which it isn't supposed to do. You can try the "Oklahoma rebuild" (use a search for the details) or do a traditional rebuild.

    Is your carb cooling fan working? This could be the problem too: Fuel boiling out of the carb when you shut down.
     
  15. mhdsummers

    mhdsummers

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    I have replaced the ignition module a few times because the motor would not start sometimes. This usually happened after the truck sat for a long time. There was always fuel in the carb when it would not start. When I replaced the module, the engine would fire right up. I did this three times and each time I had Napa check my old module and they said it checked out fine. The fouth time this happened, I replaced the module with one of the old ones and it worked. Now whenever my motor wont start, I just take the module out and put it back in and the truck starts again. This problem still happens and it is probably related to the stalling.

    I double checked timing and firing order. Timing is right on the money. I even checked my total advance (initial + mechanical + vacuum) which is at ~40.

    There is only one wire to the HEI and it is hot when the ignition is on and cold when the ignition is off.
    I have not tried to close the plug gap yet. I will try this. Plugs look good by the way.

    Can anyone think of an easy way to check spark while driving. That way I could eliminate other problems. I guess I could hook my timing light up and feed it into the cab and hold down the trigger while I drive but I bet there is a better way to do this.

    Thanks.
     
  16. FJ40Jim

    FJ40Jim The Cruiser Whisperer SILVER Star

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    Actually, that is how I do it. Install the timing light so it is visible from the driver's seat. Wrap the trigger w/ duct tape if necessary (I finally bought a light that stays on.). Now flog the vehicle until it acts up. The timing light will tell if it's sparking. :)
     
  17. dfmorse

    dfmorse

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    MHD;
    I wonder how many miles on the '78? I like the timing light idea; tape the trigger closed, put light thru right window and duck tape the light to the dash.
    How much gas is in the tank? Is the carb original? remove gas cap and drive around; just maybe the fuel line is plugged and there is neg pressure in the tank, causing fuel starving and then the fuel surging. How old is the fuel pump?

    If u live in Denver, maybe I could drive over and help u out...

    David in Denver
    3035849174
     
  18. mhdsummers

    mhdsummers

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    I'll try the timing light idea.

    dfmorse
    ~170,000 miles, smogged. Fuel pump and fuel lines are practically new. I was having a fuel problem earlier that was fixed by replacing the fuel lines and pump. All lines are new including return lines. I get good fuel flow now.
    Gas tank is 3/4 full but that does not seem to matter.

    I rebuilt the carb. I did my homework and I am pretty sure i did it correctly. I did this because I was not passing emmisions. After the rebuild, I passed emmisions :). The carb was rebuilt long before I "upgraded" to HEI (the vacuum advance on the original distributor did not work). I was not having this problem before HEI.

    I live in Broomfield. If I am still stuck after tonight, I will give you a call and maybe we can meet up. Thanks for the offer.
     
  19. Pin_Head

    Pin_Head

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    It is a strange description of problems, but it just doesn't sound like an ignition problem to me.

    Ignition problems temd to be more related to:
    1) Engine load (worse at WOT)
    2) RPM (worse at high RPM)

    If it was an intermittent wiring problem, it would crop up randomly or when you hit a bump. If it ws a component heating problem, it wouldn't idle fine and then stall when you give it gas.

    Ignition problems can be related to fuel boiling. For example if your distributors centifugal advance is not functioning the retarded timing will cause the manifold temperatures to rise dramatically.
     
  20. mhdsummers

    mhdsummers

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    OK, I just took it out with the timing light connected. When it starts to stumble and stall, the light flashes with no noticible problems. It seems to happen when I am WOT and high rpms. It might happen at 1/2 throttle also but it never happens at idle.

    When it started to die, I pulled the choke and it reved back up. I shut it off, let it sit, then went out again and when it started to stumble at WOT, I pulled the choke out (still WOT) again until it reved back up. I push the choke back in an all is good. I was able to go WOT a few more times on my way home and did not have any more problems.

    I am going to double check that my vacuum advance and centifugal advance are correct.
    I dont think I have a vacuum leak. I have 20psi at idle.
    Any other guesses?