Stalling

Discussion in 'Slant 6 Engines' started by Money Pit, Feb 3, 2018.

  1. Money Pit

    Money Pit Well-Known Member

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    I have a 70 225 with a Holley 1920. I have a Pertonix II electronic ignition conversion. The tank and fuel pick up are new. I can drive the care for about 30 minutes then it dies, like it's not getting fuel. The last time it stalled and I was towed, there wasn't any fuel in the fuel filter (clear plastic filter). The next day the filter was half full and car started right up. Since then I removed the fuel pick up (very clean), drained the gas, replaced the fuel pump and filter, went through the carb. I readjusted the float. With the engine idling, there is very little fuel in the filter (bottom of the filter barely has any fuel). If I rev the engine and hold it at a higher RPM the level of gas doesn't change. Do you think I have blocked fuel lines? Is the tank vented? If so where? I had the trunk floor replaced and then had the stalling problem. Thanks
     
  2. rustycowll69

    rustycowll69 Well-Known Member

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    years ago, when you could still buy the stuff. I bought the inside brass flex cable for speedo cables. I bought like 20 ft, and I feed it down thru the metal fuel lines, like you're snaking a drain, to make sure there is nothing clogging the steel line. Have you run it with the fuel cap off, just to make sure it's not a venting issue?
     
  3. Money Pit

    Money Pit Well-Known Member

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    I'll try that and let you know what happens. Is there another vent for the tank? Thanks
     
  4. rustycowll69

    rustycowll69 Well-Known Member

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    don't know for positive, but I think so. If it's a CA car, nearly certain. Unless the car is super original, you might be dealing with a mash-up of parts. You know vented vs non-vented cap, stock vs replacement tank, etc. Maybe a vent line or fuel supply line got crushed when the trunk floor was replaced.
     
  5. Money Pit

    Money Pit Well-Known Member

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    It's a Calif car. Is the tank vented somewhere in the engine compartment? I ordered a new gas cap. I'll see if that helps.
     
  6. rustycowll69

    rustycowll69 Well-Known Member

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    I think I'd diagnose rather than just blindly changing parts. I am not positive, but I believe CA cars in 70 had a rather elaborate venting system.
     
  7. Money Pit

    Money Pit Well-Known Member

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    Let me correct myself. The car has been in Calif most of it's "life." I don't know if its a Calif car. I don't see anything under the hood. I had a 73 V8 Challenger. It had all kinds of hoses and canisters. From underneath, I see a tube coming off the pasanger side. I need to trace where it goes.
     
  8. rustycowll69

    rustycowll69 Well-Known Member

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    IIRC the fuel tank on CA cars had like 4 or more vent tubes coming out of the upper right edge of the fuel tank, and they snaked all around back there.
    I'd just try driving without a cap, and if it didn't stall, then I'd know it was a venting problem. Make sure you have a less than full tank, too, for that test.
    If that does the trick, then maybe you could get away, at least temporarily, by drilling a small hole in the cap for a vent.
     
  9. Money Pit

    Money Pit Well-Known Member

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    Thanks for all your great advice!!!
     
  10. AJ/FormS

    AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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    Your big tip off is the empty fuel filter that refills itself. This is a classic tell tale that the the pump is sucking air. And it usually turns out to be the little rubber jumper from the sender to the hard supply line. If when you replaced it, and used gear clamps, that may be why. When using gearclamps here, they need to be the really small ones, and you need 2 per side with the screws staggered 180 degrees, then just tight not torqued to yield,lol.
    You might as well check the front one too, but that one usually leaks as a tell-tale.
    If the problem persists while driving with the cap off, then I would remove that new sender and check it.
    That air got in there somehow. And it should have passed out the float valve, as in the line is self-bleeding.So it either got sucked in right inside the tank, or through one of the jumpers on the suction side, or through a cracked hardline. The only one that doesn't leak is the rear jumper, because it's up high. The only one you can't see is in the tank.
    The pump is usually powerful enough to implode the tank, if the venting system fails.
    If your line from pump to carb is attached to the engine for stability, this point may need to be insulated to keep the hot engine from boiling the fuel in the line. On the pressure side this is not usually a problem, but with the plastic filter on there, I have seen them do that. I only use the metal bodied ones.
     
    Last edited: Feb 3, 2018
  11. Money Pit

    Money Pit Well-Known Member

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    I'll try the double clamp near the tank. I have the spring type clamps at the filter. Do I need to replace these with the gear type clamp? Thanks for the info.
     
  12. AJ/FormS

    AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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    I hate those small gear clamps.I can't trust them. Take a look at how they work. The slots for the screw threads grab the rubber and bunch it up as you tighten the screw. This leaves a little area where it could theoretically leak . So I have to put a second clamp on there to draw that tight, to make sure it can't. As time goes by, the hose rubber flows out and the gear clamp loosens it's grip.And one day the car quits running;and you can't figure out why your filter is full of air,lol.
    Do yourself a favor; swap those spring clamps onto a new jumper at the sender.
    You can always see the clamps seeping at the filter.
     
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    • rustycowll69

      rustycowll69 Well-Known Member

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      I've found that if the hose is good, the oem spring-style hose clamps are sufficient to seal in an oem situation. If I need something better, I use those FI style gear clamps, with solid banding that kind of overwrap themselves, so they don't cut into the rubber hose, and extrude rubber thru the holes in the banding.
       
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      • Money Pit

        Money Pit Well-Known Member

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        With the stiffer fuel injection hose they sell, will the oem spring clamps work?
         
      • rustycowll69

        rustycowll69 Well-Known Member

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        that's a reasonable question. Unfortunately, I can't say for certain. If the hose hasn't age hardened, I would think so on the suction side of the pump, but on the pressure side, I dunno. The good thing is that it should be apparent on the pressure side, because you'll see or feel the leakage.
         
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        • BillGrissom

          BillGrissom Well-Known Member

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          Re checking if flow from the tank is sufficient, if you remove the hose at the fuel pump inlet, fuel should pour out of the hose (say 1 gal/min have a bucket ready). That assumes the tank is almost full and car is sitting level. If true, there is no restriction on the suction side. Of course, you need much less than that even at max engine power, and can probably google a HP to fuel flow relationship.
           
        • Money Pit

          Money Pit Well-Known Member

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          I re checked the fuel flow. The gas does gush out. I agree, I don't think there is a problem between the tank and the pump. Thanks.
           
        • ESP47

          ESP47 Well-Known Member

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          I had a similar problem years ago. Couldn't figure it out so I just kind of went through everything. Finally I removed the line at the tank and removed the other end of it at the fuel pump and blew a bunch of air through it to see if there was a blockage. Nothing came out other than some gas but when I hooked it back up, it never stalled again. No clue what the cause of the problem was or if it was just a coincidence that it worked after doing that.

          My money is on a bad fuel pump. They seem to go bad when not used for any period of time. They're also one step above hot garbage these days so they come out of the box broken all the time. Maybe you can run it at home until it stalls. Then take the line off the carb and remove the coil wire and crank the engine and see if the pump is working at that moment.
           
        • rustycowll69

          rustycowll69 Well-Known Member

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          years ago, I had a bad fuel pump on a 67 273 2bbl cuda. I was working my way thru college, so I was pretty bucks-down. I'd pull the pump and hand actuate it and it would pump fuel from a pan I had filled with gas, so I put it back on, and it would work for a few days or a week, then it would quit again. So I pulled it back off, and "retested" it. I got it to pump again, so I put it back on. Shortly thereafter, when I checked the oil and I was about a quart or more overfilled it dawned on me what was happening. The pump was leaking gas into the engine. I bought a new pump, changed the oil and filter, but the damage was done.
           
        • Money Pit

          Money Pit Well-Known Member

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          I replaced the fuel pump but still had the problem. I think there may be water in the tank. At idle it ran fine. If I put in drive or reverse it would idle rough. I put a bottle of HEET in to absorb the water. I revved the engine a couple of times and it was fine. I'm trying to run the tank dry by running the engine and siphoning the gas out. I really don't want to pull the tank. I'm also going to blow the fuel fines out. Thanks for your advise.
           
        • AJ/FormS

          AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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          water is easy to see in the float-bowl