Suddenly backfiring
Lead Driver
Joined: Apr 2002
Posts: 5,339
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I would say sometimes but not always. Let’s say the ignition is faltering, perhaps due to low input voltage, bad coil, fouled plugs, etc. Lots of unburnt fuel can get dumped into the exhaust. Once in contact with a hot spot in the exhaust, it ignites and pops out the tailpipe.
A timing problem can do the same thing, but is more likely to pop through the intake.
A timing problem can do the same thing, but is more likely to pop through the intake.
Lead Driver
Joined: Jun 2013
Posts: 5,669
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From: Tolland, CT
I hope you found an auto parts store that can test your ALT and has a replacement if needed. My story, Advance Auto Parts tested my old one and told me Car Quest had the ALT I needed, which was a couple miles down the street. I went there, they swapped the pulley over onto the new ALT.
More Turbo
Joined: Oct 2020
Posts: 529
Likes: 54
From: Houston
While several folks mentioned having good connections at the battery, I didn't see anyone mention checking the other ends of the cables. Nor have I seen anyone ask about the age/condition of the cables or type of connectors : bonded or crimped. I'd take a look at them before throwing on a new alternator.
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Cross-Country
Joined: Jul 2004
Posts: 70
Likes: 3
Cables and connectors are in good shape. A few weeks ago I had gone through those and cleaned the battery posts and clamps.
Got an alternator from Autozone, 70 amp, lifetime warranty, $130.
Swapped the pulley and installed.
The battery held its voltage (12.3) through the day after charging overnight.
New readings are 13.7 from alternator. We will see how she performs going to work tomorrow morning.
Got an alternator from Autozone, 70 amp, lifetime warranty, $130.
Swapped the pulley and installed.
The battery held its voltage (12.3) through the day after charging overnight.
New readings are 13.7 from alternator. We will see how she performs going to work tomorrow morning.
Lead Driver
Joined: Nov 2013
Posts: 7,178
Likes: 1,174
While several folks mentioned having good connections at the battery, I didn't see anyone mention checking the other ends of the cables. Nor have I seen anyone ask about the age/condition of the cables or type of connectors : bonded or crimped. I'd take a look at them before throwing on a new alternator.
It's possible to have a bad connection between the alternator and battery, but that is not very common, so I hadn't suggested anything there yet.
I was considering the next steps, such as full-fielding the alternator to test it, etc. Not quite loading the parts catapult, but the alternator was probably 90% likely to be the root cause. I guess it all boils down to how much do you want to test before trying something. And in this case, the alternator was a very good educated gamble that appears to have paid off.
And now Grasshopper, you must take this pebble from my hand...
Lead Driver
Joined: Nov 2013
Posts: 7,178
Likes: 1,174
Well? It's now tomorrow evening...
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Lead Driver
Joined: Nov 2013
Posts: 7,178
Likes: 1,174
All seriousness aside, you might want to consider adding a voltmeter to your truck. If you have an idiot light, it only tells you about the problem after the fact, if at all. If you have factory gauges, the ammeter typically doesn't work, and even if does, it barely registers when a slow discharge occurs. A voltmeter is nice because you can see a problem when it first starts, long before it causes trouble.
One option if you have factory gauges:
https://www.ford-trucks.com/forums/1...olt-meter.html
I did this on my truck and it works great, and looks factory.
Or you can get a doohickey (sorry for the technical terminology) that plugs into the cigarette lighter socket and displays the voltage. I have one in my car, with an alarm that starts chirping below 11.8V. One catch with our trucks, as the lighter socket is always powered. I rewired my truck's socket (a very simple change) so it's only powered in Run or Accessory. Details here:
https://www.ford-trucks.com/forums/1...-usb-port.html
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