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Fixed: V6 Cutting out at cruising speeds?

Discussion in 'Early CJ5 and CJ6 Tech' started by sparky, May 14, 2006.

  1. May 14, 2006
    sparky

    sparky done Staff Member Founder

    Toowoomba, QLD
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    Ok, I'm really, really, really lost here.

    I put in a points distributor from MOP for a short while until my HEI arrived. When I took the Jeep out it started and ran well. I took it out on the hiway. When I did it started sputtering, and bucking and lost power until I slowed down and turned off the road. I figured it was just because I didn't have the vacuum advance hooked up.

    So last week I put in the new HEI. It did the same thing. So I bought an adjustable vacuum advance unit. I followed the instructions with it and in Rich Mott's article. In gears 1 and 2 I could run it up to 4k with no problems. Put in 3rd gear and it chokes, sputters, coughs, doesn't backfire though. It runs great at 45 mph, less than 2500 RPM, in 3rd. Faster than that it bucks. I plugged the vacuum advance thinking that was it. Still does it.

    Yesterday it did it in 2cnd gear at higher RPM until I backed my timing from 10* advanced to 5* advanced. I thought based on that it was related to the timing. I've advanced and retarded it. Disconnected the vacuum advance etc. to no avail. Like I said, in 1st and 2nd it will run all the way to 4,000 RPM, but soon as I put it in 3rd to try to keep the speed above 50 mph that I was going in 2nd and it just falls flat on its face until I slow down to 45 mph or so.

    I'm stumped. Any ideas?
     
  2. May 14, 2006
    MOP

    MOP Active Member Sponsor

    Manhattan, KS
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    Re: V6 Cutting out at cruising speeds?

    Just to be sure I am reading this right, did you hook up the vacuum advance when the Delco was installed?
     
  3. May 14, 2006
    sparky

    sparky done Staff Member Founder

    Toowoomba, QLD
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    Re: V6 Cutting out at cruising speeds?

    Nope

     
  4. May 14, 2006
    m38willys

    m38willys Jeep Vice Sponsor

    Jacksonville NC
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    Re: V6 Cutting out at cruising speeds?

    Sounds to me like your running lean at speed. Fuel filter not clogged up is it? Could be lack of fuel at speed. Sitting still you might not be able to make it do it, but under load the engine requires more fuel than in your driveway.

    I don't think it's a fire issue, I think you are running out of fuel.....

    Now to figure out why
     
  5. May 14, 2006
    sparky

    sparky done Staff Member Founder

    Toowoomba, QLD
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    Re: V6 Cutting out at cruising speeds?

    I thought about that but like I said, I can run it up to 4,000 RPM in 1st and 2nd. Heck, I drove it 1/4 mile or so around 3500 RPM in 2nd gear just to see. Wouldn't it require more fuel to do that too than to just cruise around 2500 RPM? It is/was running pretty rich too.

    Fuel filter isn't clogged, it's glass, I just looked at it.

    I don't think it's related to the distributor either but the timing of the event has me stumped. It didn't start until I started messing with the distributor recently.
     
  6. May 14, 2006
    m38willys

    m38willys Jeep Vice Sponsor

    Jacksonville NC
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    Re: V6 Cutting out at cruising speeds?

    Yes, but after sitting, you fill up the carb bowl. after running it at speed, then try 2nd again. It'll probably do it then too. If your fuel pump is dying, letting it idle may allow the pump to catch up so to speak and give you enough to run it hard for a bit. Then it gets behind the curve so to speak and struggles to keep up with fuel demand.
     
  7. May 14, 2006
    MOP

    MOP Active Member Sponsor

    Manhattan, KS
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    Re: V6 Cutting out at cruising speeds?

    Maybe, just for the process of elimination, put the Delco back in with the vacuum advance connected, set the timing to spec, and see what it does?

    I don't know if that would accomplish much, but theoretically the advance should be in a decent range with the stock distributor. As many times as you have been pulling distributors lately, that would probably only be a 10 minute exercise.

    Other Q's: What coil did you use with the Delco installed? Did you pull one off of Eugene? Do you need my old coil to try it out?

    Sorry I am not smart enough to really help, but I am trying to think of ways I would troubleshoot to eliminate advance-related issues/off a tooth/coil/etc.
     
  8. May 14, 2006
    sparky

    sparky done Staff Member Founder

    Toowoomba, QLD
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    Re: V6 Cutting out at cruising speeds?

    I have to drive out of town a couple blocks to get up to 55 mph. So I drove out of town, drove about 2 miles out. Trying to get up to 55 mph and it stalled in 3rd gear before I got to 55 mph. Turned around came back ran it up to 4k in 2cnd gear, then put it in 3rd. The float bowl should've easily been "empty" by then if I'm reading what you're saying right.

    It happens exactly as I let out on the clutch in 3rd after having it in 2nd. Not like I can run it up to 55 mph in 2nd and then drop it in 3rd and it runs for a bit then drops off. The effect is immediate, when I put it in 3rd gear.

    I've been trying to reconcile a fuel delivery issue, I just can't though. It only happens in 3rd gear above 2500 RPM.
     
  9. May 14, 2006
    MOP

    MOP Active Member Sponsor

    Manhattan, KS
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    Re: V6 Cutting out at cruising speeds?

    I have a spare fuel pump that should be in good shape.
     
  10. May 14, 2006
    sparky

    sparky done Staff Member Founder

    Toowoomba, QLD
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    Re: V6 Cutting out at cruising speeds?

    R) I could probably pull the timing cover off and replace an oil pump and distributor in 1/2 an hour now too!

    I might try it. The coil was Eugene's.

    With my vacuum advance plugged on the HEI it shouldn't be doing anything though, right? Therefore I ruled it out since I plugged it and it kept acting up.

    Mechanical advance? I set up my timing marks so I have a full 40* of readings I can take. I only have 30* of total advance. So it advances to 35* BTDC at the max. Mechanical was 15* and vacuum was giving me 15* as well.
     
  11. May 14, 2006
    sparky

    sparky done Staff Member Founder

    Toowoomba, QLD
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    Re: V6 Cutting out at cruising speeds?

    Probably worth a shot. It would either fix it or rule out one more thing.
     
  12. May 14, 2006
    m38willys

    m38willys Jeep Vice Sponsor

    Jacksonville NC
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    Re: V6 Cutting out at cruising speeds?

    Sparky, is your filter glass or plastic see through. I dealt with something similiar with my 226 truck, and the issue turned out to be that the filter element was collapsing inside the canister. When it would collapse, ot would starve for fuel and cut out. Mine was clear too, and I couldn't make it replicate it in the driveway. I would get about 1-2 miles down the road.
     
  13. May 14, 2006
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
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    Re: V6 Cutting out at cruising speeds?

    points or HEI, still occured
    vac adv or no vac adv, still occured
    std plug wires or HEI wires, still occured
    advance or retard timing, still occured

    std coil or MSD coil, still occured ?
    are we getting vac to the vac advance from the port?
    (this would be ported vac, only when you crack the throttle)
    ballast res bypassed and/or diconnected ?
     
  14. May 14, 2006
    sparky

    sparky done Staff Member Founder

    Toowoomba, QLD
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    Re: V6 Cutting out at cruising speeds?

    I just looked at it, glass with the little nylon filter that's replaceable.

    I had a fuel line collapsing that would do it 2 blocks from home. This is weirder though. It's immediately as soon as I hit 2500 RPM in 3rd gear. Doesn't matter how far I've driven or not as far as I can tell. I may just not have ever driven it far enough to really tell. I dunno. Also if I start below 2500 and go up to 2500 it stalls out. If I start out above 2500 and shift into 3rd it starts as soon as the clutch comes out.

    It does seem to be fuel related to me though.
     
  15. May 14, 2006
    sparky

    sparky done Staff Member Founder

    Toowoomba, QLD
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    Re: V6 Cutting out at cruising speeds?

    MSD isn't hooked up. One thing at a time. ;)
    Vacuum advance is from the port. I've checked my timing, it advances properly when it's hooked up.

    No ballast resistor. This was an HEI equiped vehicle before, but it was an even fire distributor.
     
  16. May 14, 2006
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
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    Re: V6 Cutting out at cruising speeds?

    I'm not convinced it's a fuel problem :?
    I've seen spark plugs/plug wires act up only under light throttle conditions.
    too bad no engine scope to throw this thing on....
    a scope pattern could tell you a lot, e-diagnosis are hard :)
     
  17. May 14, 2006
    m38willys

    m38willys Jeep Vice Sponsor

    Jacksonville NC
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    Re: V6 Cutting out at cruising speeds?

    Are you getting enough fuel though...
     
  18. May 14, 2006
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
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    Re: V6 Cutting out at cruising speeds?

    fuel pump volume test ?
    you could pull the fuel line to the carb, stick in bottle/mayo jar.
    start the Jeep up, let it idle
    should fill that bottle up very quickly, with good strong pulsations of fuel
    quick and easy to do
     
  19. May 14, 2006
    sparky

    sparky done Staff Member Founder

    Toowoomba, QLD
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    Re: V6 Cutting out at cruising speeds?

    I'll try that.

    I just think since the plug wires are newish, I used them with the old HEI that it's not them I don't think. It seemed to run fine then. Not right as evidenced by the arcing on my coil, but ran stronger than this.

    It did this with two distributors now and various timing settings and with and without the vacuum advance hooked up.

    Just doesn't make sense that it only does it in one gear at a certain speed/RPM. But no other gear at that RPM or above.

    Spark plugs? I just replaced 'em a couple weeks ago.
     
  20. May 14, 2006
    Project71-5

    Project71-5 BACON Sponsor

    Gypsum, CO
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    Re: V6 Cutting out at cruising speeds?

    Have you checked the bronze fuel filter at the fuel line inlet on the carb?
     

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