My 2001 dodge ram

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#16
It's obvious that you spent a good amount of time on my problem. I'd be happy to buy you a beer or three. As messed up as the world is at times it's good to know there are still a few decent guys out there, willing to help out for little or no monetary gain. I'm a retired machinist, living on social security, so can't pay a lot to have my truck repaired by a pro. I believe your advice and charts and diagrams are going to help me find the problem. Some of your "diagnostic technician" jargon is a little beyond me, but I have a good understanding of electricity and have always repaired my own vehicles. I'm looking forward to taking that info out to my shop and getting to work on the old girl. And perhaps finding that irish green shyte you spoke of . :) I'll post again when I find the problem. Thanks
 

billr

wrench
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#17
Is this a "hard failure" to start when it is warmed up, pretty repeatable? I'll let nickb2 guide you through the diag charts, but be sure to try some simple tests, too.

The next time it won't fire, pull off one plug wire and see if there is any spark.

Try a quick blast of starting-fluid (nickb2 hates that, would want you to use carb-cleaner) and see if it fires briefly with that.

It would be great if you could remove a plug and see if it is dry or wet immediately after a "no start" episode.

Also, check fuel pressure with a gauge, both now and when it won't start.

Use live-data to quickly check what various sensors (ECT , TPS, and CKP being prime suspects) are doing. Again, nickb2 can guide you on ways to do this inexpensively using ELM327-type connections to a laptop, pad, or phone.

Does anybody know if this engine has a trigger wheel that can run without the CMP sensor, like a 36-1 or 60-2?
 
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#18
If it fails when hot, you may have a sensor that shorts internally when hot, causing your no-start. So, locate and disconnect O2 sensor and cam sensor. ( I believe the cam sensor is inside to distributor, and the connector is a few inches outside the distributor, thankfully) Now recconnect those sensors, because that was just a practice run for later, when the engine is hot and not starting.
When it fails, disconnect O2 sensor and see if it will start. If it starts, reconnect O2 and see if it is no-start again. If reconnecting a hot O2 causes n0-start you have a shorted O2.
No luck with O2? Try disconnecting cam sensor. Try to restart. Gets a little tricky here because some cars will not start without a cam signal. Dodge/Chrysler often will start, but only after cranking about 10 seconds.
So, when your are doing your "practice run", try to start your cold engine with the cam sensor disconnected and see what happens. Remember that you may have to crank it a LONG time to get it to start when cam sensor is unplugged.
 
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#19
I'm rather amazed at all the good advice I've received on this. I was in the process of doing an ignition tune up (plugs,plug wires,distributor cap, and rotor) when I first posted here. The plugs were worn, but dry; the cap and rotor showed obvious signs of wear, but I can't tell if there's any hairline cracks or arcing; the old wires were ok. Since then it hasn't failed to start or logged any more codes. I've driven it 75 miles and restarted it when warm about 15 times without fail. I did some of the checks suggested by Nick2b and found nothing so far. Also, I had previously tried pouring a little gas into throttle body, but to no avail. I feel like I'm driving on borrowed time, but my dad always said "Max, if the summich ain't broke, don't fix it." Anyone think I might have inadvertently fixed it? Or is it impossible for an ignition "open condition" to cause all these codes and failure to start when warmed up? One other thought: I laid on top of the engine for some time changing distributor cap and rotor. Maybe I moved some wires around and fixed it without trying? Anyway I want to thank everyone, especially Nick2b for the time spent on advice.