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Thread: Engine runs great heats up dies ??Help

  1. #1
    Join Date
    Mar 2009
    Location
    Fort Worth Texas
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    12

    Default Engine runs great heats up dies ??Help

    need help 345 died at Katemcy last weeks they were open. I had to be towed around by a JEEP! No fuel pumping replaced fuel pump with electric it started ran for a little while then died?? I have replaced the 2 barrel carb (new 500 CFM Holley) Again it ran then died again same thing OK checked spark week bad- replaced coil , New Dist and wires and plugs. NOw for the spooky part I have spark I have gas I have timing she starts and runs great ----Until she gets warm operating temp can drive around block it will die and restart but can not keep it running till it cools down then same thing every time ?? What am I missing ?? Help I love this thing

  2. #2
    Join Date
    Feb 2009
    Location
    eastern washington state
    Posts
    427

    Default

    first off what are we working on and what year is it. what kind of coil did you put on there.

  3. #3
    Join Date
    Feb 2009
    Location
    Aiken, SC
    Posts
    2,423

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    When it dies, you have to check for missing spark and missing fuel again. Since it's related to temperature, it could be a lot of things.

    Choke not opening.
    Distributor wire grounding out when engine is hot.
    Vapor lock.

    I run a see-through fuel filter up near the carb so I can tell if I'm getting fuel TO the carb, but the only way to check for fuel in the carb is to take off the air cleaner and look while you move the accellerator.

    If you have gas, close the air filter and check for spark again. Don't do this if there are gas fumes present. It's easy to take a chance. Hard to put out a fire on your face and hands.

    If no spark, are the points opening? Is the pulse getting to the (-) terminal on the coil?
    Allan E.
    Curmudgeon Extraordinaire
    Charter Member, Old Hippie IH Club
    Old fashioned binder freak

  4. #4
    Join Date
    Feb 2009
    Posts
    19

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    An overheating ignition coil can cause this behavior. You didn't happen to bypass the ballast resistor, or relocate the coil to a different part of the engine compartment, did you?

  5. #5
    Join Date
    Jul 2009
    Posts
    10

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    Sounds like a classic case of vapor lock to me. Are any of your fuel lines close to ex manifolds or anything like that? Is it overheating?

  6. #6
    Join Date
    Feb 2009
    Location
    Paso Robles, Ca
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    63

    Default

    Sounds like the coil overheating...

  7. #7
    Join Date
    Mar 2009
    Location
    Fort Worth Texas
    Posts
    12

    Default 345 v8 scout 1978

    Hey thanks for the respones I have 1978 scout v8 727 auto 4wheel drive dana 20 and dana 44 front and rear. I have replaced the Carb with 500 cfm holley and the disturbutor with a direct replacement ih electronic but with a new mallory coil and plug wires ect have new electric fuel pump.
    I have gas in carb and spark and timed at right time its runs great on start up but once its warm it dies once cools down a little it starts . we researched the Vapor lock issue dosen't seem to affect anything what is the ballast resistor it it gets hot and opens then cools off could be ?? just like somebody flips switch and it all goes bad soon as warms up? Actually have lot new parts but it is doing same thing it did at Katemcy??

  8. #8
    Join Date
    Feb 2009
    Location
    Aiken, SC
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    2,423

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    Quote Originally Posted by electrican View Post
    Hey thanks for the respones I have 1978 scout v8 727 auto 4wheel drive dana 20 and dana 44 front and rear. I have replaced the Carb with 500 cfm holley and the disturbutor with a direct replacement ih electronic but with a new mallory coil and plug wires ect have new electric fuel pump.
    I have gas in carb and spark and timed at right time its runs great on start up but once its warm it dies once cools down a little it starts . we researched the Vapor lock issue dosen't seem to affect anything what is the ballast resistor it it gets hot and opens then cools off could be ?? just like somebody flips switch and it all goes bad soon as warms up? Actually have lot new parts but it is doing same thing it did at Katemcy??
    If it's the coil, it's fried. The way to test is to put a volt meter or dwell meter on it and see if you're getting pulses.

    If it's the ballast resistor, it won't reset. They tend to pop when they fail. It's just a piece of wire wrapped around something and encased in epoxy/ceramic to absorb the heat. They are designed to get hot. Get one hot and put cold water on it, it will crack, and then die soon afterward.

    If you are sucking air bubbles into the fuel via a crack, it will cause vapor lock. I have had it happen on several vehicles. Pin hole that doesn't leak prior to the fuel pump. Engine fine when cold, warms up on a hot day, bubbles create gas, gas fights the fuel pump. Ran out of gas 100 yds from the gas station today. Same thing happened. Hot day. Poured cool water on the carb, fuel started to flow again. Wasn't getting bubbles, but what little gas was in the fuel bowl evaporated when I switched tanks, got it going, and didn't have the fuel bowl quite full.

    The only way to be sure is to LOOK for fuel vapor and LOOK for spark the way I mentioned in the earlier post. The new electronic module could be heating up, too. There are just too many things that can cause this to be guessing and trying to replace different parts until it works.
    Allan E.
    Curmudgeon Extraordinaire
    Charter Member, Old Hippie IH Club
    Old fashioned binder freak

  9. #9
    Join Date
    Mar 2009
    Location
    Fort Worth Texas
    Posts
    12

    Default ok have a manual now

    Hey I have the scout manul now been looking at this thing pretty hard. I bought the Scout for 500 dollars out of field in Palmer Texas. replaced all the brake system and little work she been running great. 4 in lift 35 in tires my 15 yr old boy is in heaven a lot better than the money pit dirt bike. I think it is a vacum problem going replace all the vacum hoses The question is if I want run this thing naked I need Vacum hose from Distrubutor to carb that is it right all egr and ect can be pluged up blocked off? did this on an old chevy one time it ran great. also the electrical system by pervious deer hunters ect.. needs help if I want to do away with every thing but push button start I need wire from postive and negative from disturbutor to coil and battery wire from Battery to starter with wire from push button from to solinoid and solonid to alternater and of course frame ground this should make it run. I can not think of any thing internal in engine that would do this? it runs to good and starts to eaasy when cold to just set there and die and not start till it gets cool again?? Thanks

  10. #10
    Join Date
    Jul 2009
    Posts
    10

    Default

    Does it have spark when its hot?

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