f100 ignition loses rpms

[oddnumb]

2001 f100 runs @ 6000 rpm for two minutes and then just drops to 4800 rpm. feels like it a cylinder down till i throttle back under 2000 rpm and picks cylinder up. new plugs fresh fuel- filters - and water seperator. does anyone think one of the coil packs ??


thanks

Brett

[boats.net]

It could be an ignition or fuel problem, most of time it's a fuel problem, debris in carbs or filter that will only get sucked at high speeds. The ignition can be tested with a timming light, once you find out which cylinders are breaking down you can swap coils to find out if it's a bad coil.

[oddnumb]

i have cleaned all of the fuel filters and drained the tank. is it possible one of the carb float bowls
is sticking. if i run at 5000 rpm it takes longer for the cylinder to drop then at 6000 rpm.


thanks brett

[jb123]

sounds lik a fuel restriction to me and when you run less rpms the fuel lasts longer. is your primer ball fine at time of issue? also check your tank vent,pickup tube as sometimes at factory they are fitted with a filter screen.usually an electrical prob will occur all the time.

[Ken]

brett,
Sure sounds to me like you have diagnosed your problem. Might try doing a shock treatment with SeaFoam or RingFree to see if that will clean up the carbs a little, and maybe free that stuck float/valve. If not, then probably will have to remove, teardown, and clean - a carb kit might be in order.
Good luck [img]smile.gif[/img] ,
Ken K