something finally snapped inside
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Joined: Jan 2003
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From: Munroe falls, Ohio
something finally snapped inside
i have a 1984 f250 with a 351w with around 150k miles. the engine has been good up till my long roadtrip(512 miles total). it was running fine for the first 200miles of the trip, i was getting 17.5mpg cruising at 65mph. then as i was climbing some PA mountains, the engine decided not to go over 45-50mph no matter how hard you hit the gas. it was struggling, kinda like missfiring, no pinging. when i was driving back in ohio(flatter land) i was able to go around 60mph. the second tank of gas i only got 13.1mpg
i've checked
timing:12*, stock is 10*
vacuum:16" steady, doesnt changed when i advance/retard timing
compression: 150psi on six cylinders and 130psi on two next to eachother
timing chain: has around 8* slop before on i went on the trip
spark plugs:6 are black, oily depostis, not running rich; 2 are whiteish, perfect combustion
runs good at low loads/high rpms but when you put on a high load, it sturggles as low as 2000rpms.
im gonna put in a new timing chain(summit roller, straight up), if that doesnt help then ill run it till it blows and get a rebuilt one.
i've checked
timing:12*, stock is 10*
vacuum:16" steady, doesnt changed when i advance/retard timing
compression: 150psi on six cylinders and 130psi on two next to eachother
timing chain: has around 8* slop before on i went on the trip
spark plugs:6 are black, oily depostis, not running rich; 2 are whiteish, perfect combustion
runs good at low loads/high rpms but when you put on a high load, it sturggles as low as 2000rpms.
im gonna put in a new timing chain(summit roller, straight up), if that doesnt help then ill run it till it blows and get a rebuilt one.
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Posting Guru
Joined: Jan 2003
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From: Munroe falls, Ohio
10* btdc is stock
it will stumble at 2000 rpms in third gear or 4000 rpms in second gear.
fuel filter was changed last fall.
fuel pump might be original or not, i didnt change it when i got it at 111k miles.
it has a new coil but ill swap it out for another one.
but why would only 5 cylinders have an oily/black coating while the other 3 cylinders the plugs look normal(1 plug on the left bank and 2 plugs on the right bank)
it will stumble at 2000 rpms in third gear or 4000 rpms in second gear.
fuel filter was changed last fall.
fuel pump might be original or not, i didnt change it when i got it at 111k miles.
it has a new coil but ill swap it out for another one.
but why would only 5 cylinders have an oily/black coating while the other 3 cylinders the plugs look normal(1 plug on the left bank and 2 plugs on the right bank)
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Posting Guru
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From: Munroe falls, Ohio
the coil is an AZ one, just put it on last fall (for no reason, original was fine).
the wires are bosch, put those on 2/21/04
the plugs are champion platinum(stock replacement) bought with the wires.
the plugs dont have a fluffy dry coating meaning a rich condition, they have a oily/black/wet coating. plus i dont see how only 5 plugs have this coating.
the wires are bosch, put those on 2/21/04
the plugs are champion platinum(stock replacement) bought with the wires.
the plugs dont have a fluffy dry coating meaning a rich condition, they have a oily/black/wet coating. plus i dont see how only 5 plugs have this coating.
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Posting Guru
Joined: Jan 2003
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From: Munroe falls, Ohio
but why only 5 plugs, i would understand all 8 but not only 5.
the pcv still ticks, but ill clean it and see.
and why did it start doing this when i was climbing the PA mountains, cruising at 2600 rpms and not when im holding first gear at 5000, or hauling 5000 lbs in the bed with the gas pedal to the ground?
the pcv still ticks, but ill clean it and see.
and why did it start doing this when i was climbing the PA mountains, cruising at 2600 rpms and not when im holding first gear at 5000, or hauling 5000 lbs in the bed with the gas pedal to the ground?
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Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
strange to say the least. i would just buy a new pcv valve. they are cheap . hopefully someone will chim in. what condition is the carb in? maybe it needs rebuilt or adjusted
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Thread Starter
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Posting Guru
Joined: Jan 2003
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From: Munroe falls, Ohio
i got some time to take the motor apart and heres what i found.
the timing chain was original with 150k miles on it.
it also had .5" deflection, the maximum limit for the chain.
it also had a two piece fuel pump eccentric.
the timing chain was original with 150k miles on it.
it also had .5" deflection, the maximum limit for the chain.
it also had a two piece fuel pump eccentric.