Engine dies at idle
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From: spring tx
Engine dies at idle
Hi, I have a 69 coupe with a 350engine, Edelbrock heads, new Mallory hei dist. and a new 650 Holly carb. The engine runs fine if the rpm's are over 1,000 but it will die after running about a minute or less if under 1,000 rpm's. The engine will not start again unless I wait a few minutes then it fires right back up. I replaced the fuel filter but it did not help. I'm thinking more electrical than fuel. Any ideas? Thanks.
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From: spring tx
I checked the idle screws and they were out 1.5 turns but I do appreciate your suggestion. But now the engine won't start at all. I am getting fuel to the carb so it seems to be an elect. problem. I double checked the power to the distributor by running a jumper cable from the pos. battery terminal to the "battery" terminal on the distributor and confimed power with a test light. When I cranked the engine over I saw that I was not getting a spark to the plugs. This is a new distributor and has been working fine until now.
Le Mans Master
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From: Gladstone MO
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Before it dies, is it loading up? Mixture too rich from idle not being adjusted correctly, power valve being wrong or bad, float level too high, needle & seat leaking, vacuum leak(s), float(s) saturated with fuel and too heavy, choke not adjusted properly, that list keeps going.
Very UNLIKELY there's an electrical problem. Normal operation for an electrical problem is it happens and you walk. (or get towed). If you still had the original ignition, I'd suggest the resistance wire in the harness, but the HEI should not have been hooked up to the factory wires anyway.
Nothing like posting at the same time!
Pull a plug wire off, put an old spark plug in it, lay it on the intake so you can see it and crank. If it sparks that proves THAT plug wire. If not, then look at the cap and rotor, and coil.
Very UNLIKELY there's an electrical problem. Normal operation for an electrical problem is it happens and you walk. (or get towed). If you still had the original ignition, I'd suggest the resistance wire in the harness, but the HEI should not have been hooked up to the factory wires anyway.
Nothing like posting at the same time!
Pull a plug wire off, put an old spark plug in it, lay it on the intake so you can see it and crank. If it sparks that proves THAT plug wire. If not, then look at the cap and rotor, and coil.
Last edited by TimAT; Apr 30, 2009 at 02:12 PM.
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From: spring tx
TimAt, I checked for spark both at the spark plug and at the distributor. There is no spark at either location. I know I have power to the distributor so now I will check the ground.
Thanks for the input.
Thanks for the input.
Burning Brakes
Joined: Aug 2005
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From: Europe, France
Do you use a vacuum advance on your distributor, and is it hooked to manifold vacuum ?
As RPM decreases, engine vacuum decreases too. At a certain point, vacuum advance will start to decrease, and engine dies suddenly...
A vacuum leak can lead to the same result.
As RPM decreases, engine vacuum decreases too. At a certain point, vacuum advance will start to decrease, and engine dies suddenly...
A vacuum leak can lead to the same result.
Le Mans Master
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From: Gladstone MO
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Distributor will be grounded thru the block. No issue there. Check the pickup coil - it's where the points used to be- if a wire to it is pinched/grounded/ broken then no spark. Use your voltmeter on the OHMS setting and check continuity thru the pickup coil, and then the ignition coil too. after that, it's possibly the module, if that dizzy has one.
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From: spring tx
Yes I do have a vacuum advance but would a loss of vacuum lead to a loss of spark at start up? I don't believe it would but I'm at a loss right now. My next step is to replace the coil. It is a new distributor but it could be bad. My distributor is a Mallory v8 billet with tach. drive.
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From: spring tx
Distributor will be grounded thru the block. No issue there. Check the pickup coil - it's where the points used to be- if a wire to it is pinched/grounded/ broken then no spark. Use your voltmeter on the OHMS setting and check continuity thru the pickup coil, and then the ignition coil too. after that, it's possibly the module, if that dizzy has one.
Pro
Joined: Jul 2008
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From: Millersville, MD
I checked the idle screws and they were out 1.5 turns but I do appreciate your suggestion. But now the engine won't start at all. I am getting fuel to the carb so it seems to be an elect. problem. I double checked the power to the distributor by running a jumper cable from the pos. battery terminal to the "battery" terminal on the distributor and confimed power with a test light. When I cranked the engine over I saw that I was not getting a spark to the plugs. This is a new distributor and has been working fine until now.
Last edited by Vette79C3; Apr 30, 2009 at 03:23 PM.
Le Mans Master
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From: Santa Ana CA
Check the fuel levels in the float bowls.
I bet they are too high and gas is spilling over and creating an over-rich mixture at idle that will stall the engine.
I recently went through this when I changed the jets on my 600 dp and removed the slosh tubes thereby changing the float level on the secondaries creating an over-high condition.
I bet they are too high and gas is spilling over and creating an over-rich mixture at idle that will stall the engine.
I recently went through this when I changed the jets on my 600 dp and removed the slosh tubes thereby changing the float level on the secondaries creating an over-high condition.
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From: spring tx
Check the fuel levels in the float bowls.
I bet they are too high and gas is spilling over and creating an over-rich mixture at idle that will stall the engine.
I recently went through this when I changed the jets on my 600 dp and removed the slosh tubes thereby changing the float level on the secondaries creating an over-high condition.
I bet they are too high and gas is spilling over and creating an over-rich mixture at idle that will stall the engine.
I recently went through this when I changed the jets on my 600 dp and removed the slosh tubes thereby changing the float level on the secondaries creating an over-high condition.
Le Mans Master
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From: Santa Ana CA
"The engine runs fine if the rpm's are over 1,000 but it will die after running about a minute or less if under 1,000 rpm's. The engine will not start again unless I wait a few minutes then it fires right back up."
When running over 1,000 RPM the engine pulls enough fuel such that it doesn't slosh over into the venturies. Also the blades are open enough for air to pass through so although it is rich, it runs
At idle the fuel sloshes over causing an over-rich condition killing the engine. Engine doesn't start right up because the intake is full of fuel (over-rich).
In a few minutes, enough evaporates out such that the engine can start. Classic symptoms.
You did properly adjust the float levels when you installed the Holley as recommended by Holley any time a double pumper carb is installed didn't you? Pull off the site plugs (or put in the clear plugs) while cranking the engine a few times (or better yet if you can get it to run) and see if fuel gushes out. It shouldn't and there should be a very small trickle at the most.
Last edited by toddalin; Apr 30, 2009 at 08:31 PM.
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From: spring tx
Yes you are correct, that was from my first post. In my subsequent posts I said that I found that lack of spark was the problem.
I have looked into the no spark theory further and have found that the hot(red)wire from the distributor to coil harness was hanging by one strand of wire. It appears that it worked itself loose while the engine was running. Seems to be a poor connection made in production. I will try to be more clear in the future.
I have looked into the no spark theory further and have found that the hot(red)wire from the distributor to coil harness was hanging by one strand of wire. It appears that it worked itself loose while the engine was running. Seems to be a poor connection made in production. I will try to be more clear in the future.
From your first post:
"The engine runs fine if the rpm's are over 1,000 but it will die after running about a minute or less if under 1,000 rpm's. The engine will not start again unless I wait a few minutes then it fires right back up."
When running over 1,000 RPM the engine pulls enough fuel such that it doesn't slosh over into the venturies. Also the blades are open enough for air to pass through so although it is rich, it runs
At idle the fuel sloshes over causing an over-rich condition killing the engine. Engine doesn't start right up because the intake is full of fuel (over-rich).
In a few minutes, enough evaporates out such that the engine can start. Classic symptoms.
You did properly adjust the float levels when you installed the Holley as recommended by Holley any time a double pumper carb is installed didn't you? Pull off the site plugs (or put in the clear plugs) while cranking the engine a few times (or better yet if you can get it to run) and see if fuel gushes out. It shouldn't and there should be a very small trickle at the most.
"The engine runs fine if the rpm's are over 1,000 but it will die after running about a minute or less if under 1,000 rpm's. The engine will not start again unless I wait a few minutes then it fires right back up."
When running over 1,000 RPM the engine pulls enough fuel such that it doesn't slosh over into the venturies. Also the blades are open enough for air to pass through so although it is rich, it runs
At idle the fuel sloshes over causing an over-rich condition killing the engine. Engine doesn't start right up because the intake is full of fuel (over-rich).
In a few minutes, enough evaporates out such that the engine can start. Classic symptoms.
You did properly adjust the float levels when you installed the Holley as recommended by Holley any time a double pumper carb is installed didn't you? Pull off the site plugs (or put in the clear plugs) while cranking the engine a few times (or better yet if you can get it to run) and see if fuel gushes out. It shouldn't and there should be a very small trickle at the most.
Le Mans Master
Joined: Oct 2000
Posts: 8,897
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From: Santa Ana CA
Yes you are correct, that was from my first post. In my subsequent posts I said that I found that lack of spark was the problem.
I have looked into the no spark theory further and have found that the hot(red)wire from the distributor to coil harness was hanging by one strand of wire. It appears that it worked itself loose while the engine was running. Seems to be a poor connection made in production. I will try to be more clear in the future.
I have looked into the no spark theory further and have found that the hot(red)wire from the distributor to coil harness was hanging by one strand of wire. It appears that it worked itself loose while the engine was running. Seems to be a poor connection made in production. I will try to be more clear in the future.
Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
One strand of wire 20 gauge won't carry enough current to make a taillight bulb light up. SO the coil is not getting the voltage OR current it needs to work properly. You may have solved all your problems with one "shot-over-the-bow" ( that's "bow as in the front of a boat, btw)
Get that fixed and let us know.
Get that fixed and let us know.
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From: spring tx
Yes I may be back to where I started. I will not know until I replace the hei module in my dist. I repaired the broken wire I refered to in my earlier post and it still has no fire at the plugs. I believe that I fried the module while charging my battery. Appearantly this is a no no. I now Know that you need to disconnect the dist. power. or remove the battery cables before attempting to charge. It will be a few days before I get the new module.
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From: spring tx
Just a follow up on my post. I replaced the ignition module in my 69 today and the engine fired right up. Most of you know this already but for the few who do'nt (including me until last week), never charge or attempt to jump a car that has a elect. ignition module using a battery charger. You will kill the module. If you do use a battery charger first disconnect the battery or disconnect the hot wire to the distributor.
