vapor lock or ignition module problem:
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vapor lock or ignition module problem:
How can you tell a vapor lock from ignition module problem. Truck stalls and starts after cooling down. 750 edlebrock with rubber fule hose across the front of manifold with inline fule filter. 460/77 250.
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Joined: Feb 2004
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From: Portland, OR
Rule out rust in the gas tank first. I had the same issue. Crack open the fuel filter and look for rust particles.
What was happening to me was the filter would clog, and then the particles would receed once the motor sat for a while. Ran 15-20 minutes and would surge and cut out again.
Does it surge before it stalls? That would indicate fuel starvation.
What was happening to me was the filter would clog, and then the particles would receed once the motor sat for a while. Ran 15-20 minutes and would surge and cut out again.
Does it surge before it stalls? That would indicate fuel starvation.
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Joined: Mar 2003
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From: AZ.
What worked for me a couple times was to put a wet rag on the modual to cool it down. It got my truck to the job and home again. I joked with a niece when she said her car wouldn't start when hot and told her it had a headache. I raised the hood and showed her how to put a cold compress on it's brain. She made it home, her husband didn't believe it and told her I was nuts. 
Posting Guru
Joined: Jul 2001
Posts: 1,613
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From: Gainesville, FL
Jerry,
You are nuts, but let's try and stick to the subject at hand.
The odds of cooling a ignition module and having it work are slim to none. That's a rather incredilble tale. By the time a module fries, its silicone filling is usually on the fender well. This means it should be suseptible to moisture. This means a wet rag should spell short circuit. Oh well, I guess I'd rather be lucky, than good.
I keep an extra ignition module around and have never needed one in over 14 years. Try it.
Good Luck,
KingFisher
PS If the vehicle stalls while hot check it for spark. I keep an extra spark plug around and plug it into a spark plug wire and have someone turn it over. If you have no spark, it's probably the ignition module. Start there.
You are nuts, but let's try and stick to the subject at hand.
The odds of cooling a ignition module and having it work are slim to none. That's a rather incredilble tale. By the time a module fries, its silicone filling is usually on the fender well. This means it should be suseptible to moisture. This means a wet rag should spell short circuit. Oh well, I guess I'd rather be lucky, than good.
I keep an extra ignition module around and have never needed one in over 14 years. Try it.
Good Luck,
KingFisher
PS If the vehicle stalls while hot check it for spark. I keep an extra spark plug around and plug it into a spark plug wire and have someone turn it over. If you have no spark, it's probably the ignition module. Start there.
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Joined: Jul 2002
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From: Long Island USA
Originally Posted by dfisher1
Jerry,
You are nuts, but let's try and stick to the subject at hand.
The odds of cooling a ignition module and having it work are slim to none. That's a rather incredilble tale. By the time a module fries, its silicone filling is usually on the fender well. This means it should be suseptible to moisture. This means a wet rag should spell short circuit.
You are nuts, but let's try and stick to the subject at hand.
The odds of cooling a ignition module and having it work are slim to none. That's a rather incredilble tale. By the time a module fries, its silicone filling is usually on the fender well. This means it should be suseptible to moisture. This means a wet rag should spell short circuit.
Lots of times, all sorts of "modules" fail because of a bad solder joint - nothing wrong, just a bad connection. Heat it up, it stops conducting, cool it down, it conducts. Or not.
Back to the original poster, try the other people's suggestions. Check for squirt from the accelerator pump. Check spark when not starting. Vapor lock is pretty evident if you take off the air-cleaner - just make sure you're not smoking
Posting Guru
Joined: Jul 2001
Posts: 1,613
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From: Gainesville, FL
All,
Vapor lock is most commonly evident on a restart. After you shut the vehicle down the motor heats up for a short time and boils the gas. If it boils while running, you've got a serious problem. The vehicle should be running on the hot side to cause such a situation. Does the fuel line get anywhere close enough to the exhaust to heat it up? Is the exhaust clogged or restricted in anyway. If you have dual exhaust and one side is restricted more than the other, the back pressure will push through the bypass in the intake manifold and boil your gas. A stuck heat riser could cause this and it could happen quickly (i.e. 4 or 5 minutes).
Good Luck,
KingFisher
Vapor lock is most commonly evident on a restart. After you shut the vehicle down the motor heats up for a short time and boils the gas. If it boils while running, you've got a serious problem. The vehicle should be running on the hot side to cause such a situation. Does the fuel line get anywhere close enough to the exhaust to heat it up? Is the exhaust clogged or restricted in anyway. If you have dual exhaust and one side is restricted more than the other, the back pressure will push through the bypass in the intake manifold and boil your gas. A stuck heat riser could cause this and it could happen quickly (i.e. 4 or 5 minutes).
Good Luck,
KingFisher
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From: alaska
excellent
Originally Posted by krewat
Um, if you heat it up (engine running) and it fails, and when it cools down it works, then a cold rag is a good bit of applied physics. One of those first-aid ice-packs would probably work too
Lots of times, all sorts of "modules" fail because of a bad solder joint - nothing wrong, just a bad connection. Heat it up, it stops conducting, cool it down, it conducts. Or not.
Back to the original poster, try the other people's suggestions. Check for squirt from the accelerator pump. Check spark when not starting. Vapor lock is pretty evident if you take off the air-cleaner - just make sure you're not smoking
Lots of times, all sorts of "modules" fail because of a bad solder joint - nothing wrong, just a bad connection. Heat it up, it stops conducting, cool it down, it conducts. Or not.
Back to the original poster, try the other people's suggestions. Check for squirt from the accelerator pump. Check spark when not starting. Vapor lock is pretty evident if you take off the air-cleaner - just make sure you're not smoking
excellent , really excellent , respectfully , bob
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