I have a 1961 Comet with a 68 200 six ,T5 Tranny , Summit HEI ignition , Headers , duel exhaust , Holley one barrel knockoff carb . The problem it will start and run perfect cold <I can drive for a mile or two , then will start to miss with no power and die . I can sit for a minute fire it up and drive some , then repeat . I thought vapor lock but will do it at 70 degrees . fuel pump new . tank clean ,gas filter clean .The metal fuel line has not been replaced is it posible to have small holes that suck air into the pump .? Lost mecanic say 5 different things . Any Ideas Thanks
All Small Six Fuel or ignition problem
- Thread starter oldfalcon57
- Start date
This relates to all small sixes
Take some of the guesswork out of it. Plumb in a temp. mechanical fuel pressure gage, Tape down to cowl with rags.
How is the HEI power wired in? It needs battery voltage wired through a relay for reliability.
Sounds like your Comet has some good stuff on it. I hear some negative about comments about new fuel pumps these days but probably not that.
philford
Well-known member
put a small lamp across the coil primary,( the two wires on the coil) crank it , if it blinks fast during cranking that is normal. if you loose the ignition pulses to your coil , it will not blink.
I think that is easier to monitor than, especially if it becomes intermittent..
I left mine connected to an LED permanently and just tucked it under my dash so I can see it when it want to .
that small lamp or LED is then just in parallel with the primary coil, when it gets a pulse (to create a spark) the lamp blinks. if you start it the lamp can't blink that fast so it will appear to glow dimly.
you can check for a spark at the plugs by grounding one and watching or by connecting a timing light. sometimes Ill tape the button down when alone to observe the flash of the timing light from the key.
if you saw you had an impulse at the primary and no output from the secondary ( no spark) that could be a bad coil. I think a lot more often people replace coils and that is not the issue but they could possibly go intermittent, I've never seen it happen to me in a car.
I have a boat that might have that issue because the wiring for the stator and trigger is encased in plastic ( under the flywheel) the plastic cracks and I found my boat would run for about 5 mins and then quit. I think its heating up and loosing the spark.
I think what happens there is the coil of wire being encased in plastic gets damaged as the plastic ages out and cracks, maybe breaking the embedded wire somewhere.
on electronic ignition cars, the module strapped to the distributor can fail and then you ll have no pulse. If it's an old points distributor it could be to do with that, maybe dirty points etc.
you can check for spark coming out of the coil just as you normally would at # 1 cyl. if you have a spark coming out of the coil and it doesn't make it to the cylinders that's a problem with the cap , plug wires, rotor.
if you put a spark plug on the coil and see a spark then it could still be intermittent,.. it is possible a bad coil goes intermittent. It's not my first suspect.
if the pulse on the primary is intermittent then the issue is not a bad coil , its a problem with the coil not being fed the pulse consistently. Id use the small lamp or LED across the primary coil to monitor in real time while troubleshooting. of course physically clean and inspect the cap and rotor. look for cracks or carbon tracking or dirty electrodes int he cap, the other thing that's caught me a few times is one wire just not seated fully, cheapo made in china plug wire sets. sometimes Ive seen the wire come unclipped down inside the spark plug boot. give each wire a really good wiggle and a solid push if you feel one click and go on further, that might be the culprit.
cheap distributor caps with aluminum electrodes. try to get ones with brass or copper electrodes. look inside the cap at the flat places. see if they look corroded or blackened. Ill often take a sharp pointy knife and give them a scrape to clean, as a temporary measure if I find them in a sorry state.
I think that is easier to monitor than, especially if it becomes intermittent..
I left mine connected to an LED permanently and just tucked it under my dash so I can see it when it want to .
that small lamp or LED is then just in parallel with the primary coil, when it gets a pulse (to create a spark) the lamp blinks. if you start it the lamp can't blink that fast so it will appear to glow dimly.
you can check for a spark at the plugs by grounding one and watching or by connecting a timing light. sometimes Ill tape the button down when alone to observe the flash of the timing light from the key.
if you saw you had an impulse at the primary and no output from the secondary ( no spark) that could be a bad coil. I think a lot more often people replace coils and that is not the issue but they could possibly go intermittent, I've never seen it happen to me in a car.
I have a boat that might have that issue because the wiring for the stator and trigger is encased in plastic ( under the flywheel) the plastic cracks and I found my boat would run for about 5 mins and then quit. I think its heating up and loosing the spark.
I think what happens there is the coil of wire being encased in plastic gets damaged as the plastic ages out and cracks, maybe breaking the embedded wire somewhere.
on electronic ignition cars, the module strapped to the distributor can fail and then you ll have no pulse. If it's an old points distributor it could be to do with that, maybe dirty points etc.
you can check for spark coming out of the coil just as you normally would at # 1 cyl. if you have a spark coming out of the coil and it doesn't make it to the cylinders that's a problem with the cap , plug wires, rotor.
if you put a spark plug on the coil and see a spark then it could still be intermittent,.. it is possible a bad coil goes intermittent. It's not my first suspect.
if the pulse on the primary is intermittent then the issue is not a bad coil , its a problem with the coil not being fed the pulse consistently. Id use the small lamp or LED across the primary coil to monitor in real time while troubleshooting. of course physically clean and inspect the cap and rotor. look for cracks or carbon tracking or dirty electrodes int he cap, the other thing that's caught me a few times is one wire just not seated fully, cheapo made in china plug wire sets. sometimes Ive seen the wire come unclipped down inside the spark plug boot. give each wire a really good wiggle and a solid push if you feel one click and go on further, that might be the culprit.
cheap distributor caps with aluminum electrodes. try to get ones with brass or copper electrodes. look inside the cap at the flat places. see if they look corroded or blackened. Ill often take a sharp pointy knife and give them a scrape to clean, as a temporary measure if I find them in a sorry state.
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