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69 F250 360 4 spd. It misses under half to full throttle in any gear at any point in time. I put new plug wires on it, didnt help. It has about a half a tank of 8 nearly year old gas. I added an additive and fresh gas. I have been waiting to run the old gas through it before I do any timing adjustments. Could the gas be causing this?
Thanks
Aaron
Thanks
Aaron
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From: Comox Valley, Canada
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Is that 8 year old gas?? What is the mixture of new to old gas? That old gas could cause lack of power etc etc.
Is the carb possibly gummed up from sitting with gas in it so long?? Maybe a partially blocked fuel filter? Vaccuum advacnce not working?
There is probably more I have missed
Sparky
Is the carb possibly gummed up from sitting with gas in it so long?? Maybe a partially blocked fuel filter? Vaccuum advacnce not working?
There is probably more I have missed
Sparky
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Ok I have more. When its cold, then engine will not run with the choke on. I bought some carb cleaner and was spraying it down the throat tonight in the dark. When the engine would stumble I could see the plugs arc on the right cylinder bank? Im lost.
Aaron
Aaron
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From: Comox Valley, Canada
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>Sorry, 8 month old gas. How would I check the vaccuum
>advance?
Connect a timing light and watch the timing marks when you rev the engine, you should see them advance from base timing you see at idle.
Sparky
>advance?
Connect a timing light and watch the timing marks when you rev the engine, you should see them advance from base timing you see at idle.
Sparky
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From: Comox Valley, Canada
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>Ok I have more. When its cold, then engine will not run
>with the choke on. I bought some carb cleaner and was
>spraying it down the throat tonight in the dark. When the
>engine would stumble I could see the plugs arc on the right
>cylinder bank? Im lost.
>Aaron
The plug wires are arcing??? If they are new I would return them. They shouldnt arc unless there is a break in the insulation. Possibly they aren't pushed on tight enough, but I would bet on a crack in the insulation.
Sparky
>with the choke on. I bought some carb cleaner and was
>spraying it down the throat tonight in the dark. When the
>engine would stumble I could see the plugs arc on the right
>cylinder bank? Im lost.
>Aaron
The plug wires are arcing??? If they are new I would return them. They shouldnt arc unless there is a break in the insulation. Possibly they aren't pushed on tight enough, but I would bet on a crack in the insulation.
Sparky
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The problem has gotten worse, now when driving it backfires only after running in one gear for a few minutes and being warm. Once it starts backfiring (exhaust) it wont stop until you turn the truck off and start it again. I changed the accelerator pump and put brand new wires on the truck, it still misses and stumbles like before, but I didnt let it warm up long enough to see if it still backfires. I guess the distributor is about all thats left?
Thanks
Aaron
Thanks
Aaron
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From: Comox Valley, Canada
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Well timing immediately comes to mind when I hear of backfiring....or how about a crack in the distributor cap, or carbon tracks on an old cap causing cross firing of the plugs.......
Ok any more ideas guys?
Sparky
Ok any more ideas guys?
Sparky
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I started driving the truck friday evening, it hadnt been driven much before then. Starting sunday, it began running poorly, ran great before then. I will check the cap again, but I looked it over and never noticed a crack, no carbon buildup though, I checked the cap rotor and points the other day. The truck idles fine, so I doubt it's a vaccuum leak. The plugs are not brand new, but I will check them. I was thinking more along the lines of the vaccuum advance? I am at work now, so I can't check it until I get home.
Thanks
Aaron
Thanks
Aaron
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From: Gainesville, FL
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Aaron,
This is a weak spark. At an idle the vehicle does not create as much compression. Compression actually supresses ignition. As you rev up your motor, your compression increases and your weak spark fails. Your points should be some where around 0.016 inch at peak. What's yours? If the gap is too large you will not develope the spark needed.
As far as your new spark pug wires arcing, that's wrong and the likely symptom of your backfiring. Did they arc at the plug, the cap, or at some point between? Did they arc from one to another or to ground/block. This is a weird one.
Good Luck
KingFisher
This is a weak spark. At an idle the vehicle does not create as much compression. Compression actually supresses ignition. As you rev up your motor, your compression increases and your weak spark fails. Your points should be some where around 0.016 inch at peak. What's yours? If the gap is too large you will not develope the spark needed.
As far as your new spark pug wires arcing, that's wrong and the likely symptom of your backfiring. Did they arc at the plug, the cap, or at some point between? Did they arc from one to another or to ground/block. This is a weird one.
Good Luck
KingFisher
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I swapped in a good distributor and everything is great now. I didn't have a timing light and I ended up with the timing a little retarded, seeing as its not making the power it should. I get it dialed in this weekend.
Thanks for the help
Aaron
Thanks for the help
Aaron
