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Discussion Starter #1
Was at the river this weekend and occasionally my rpm would fall off by a few hundred, back out of the throttle, hammer down, rpms are back for a while. What do y'all think it is?
 

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Was at the river this weekend and occasionally my rpm would fall off by a few hundred, back out of the throttle, hammer down, rpms are back for a while. What do y'all think it is?
Fuel pump can't keep up.
 

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Need more details??

Was at the river this weekend and occasionally my rpm would fall off by a few hundred, back out of the throttle, hammer down, rpms are back for a while. What do y'all think it is?
My first guess, and only a guess based on the available info, would be fuel supply. Do you have a fuel pressure gauge? If you do, what was the pressure when it dropped off? Has it ever done this before? Any changes, any thing at all, since the last trip when it didn't drop the Rs? What is the history of this current set up? The idea that it regained the Rs by simply backing out and stepping on the gas again would seem to me to be fuel related. Either pump, filter, supply from tank(s) dropping due to vapor lock, or possibly a vacuum issue from the tank vent.... When you backed off and dropped the nose, the fuel would shift in the tank and maybe re-cover the pick up....Many, many possibilities, but I think an ignition issue would not "fix it's self" that quickly. However, I've seen marginal coils do some funny things in an intermittent hit and miss condition...More info Lucky??....
Ray
 

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Discussion Starter #4
My first guess, and only a guess based on the available info, would be fuel supply.
Do you have a fuel pressure gauge? YES , 6.5 PSI is where the regulator is set, it didn't drop when this happened
Has it ever done this before? Nope
Any changes, any thing at all, since the last trip when it didn't drop the Rs? Added a Place Droop with rideplate
What is the history of this current set up? Same setup for the past 3 years
More info Lucky??....
Ray
When I say I got out of the throttle and back into it, I'm talking foot off, foot right back on the throttle, no time for the nose to drop.
 

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Pedal job

When I say I got out of the throttle and back into it, I'm talking foot off, foot right back on the throttle, no time for the nose to drop.
So basically you're saying you "pedaled it"... Hmmmm, how about in the past? Any changes since the last time out? Is the motor "nosing over", like running out of camshaft or vacuum? When you lift and stab it, the only thing you're doing is adding the accelerator pump squirt to the fuel supply, which could grab a few Rs back, but it should be short lived. ???? Any float level changes lately? ... OK, another guess. Is it possible your valve springs are going away? Weak springs could set up a harmonic vibration that could get the springs shaking sideways and could cause the valves to begin to float. Lifting, even for a split second could get the springs back in order for a short time until the process begins all over, and the Rs drop again... Again, do you have a fuel pressure gauge? And/or a vacuum gauge? ... Sloppy/floating valves should cause a drop in vacuum.... F/pressure would be my first investigation...After that, you might look at max ignition advance for any changes since it was set, but that is down my list of possibles. IMO, it could be the springs....
Ray
 

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Discussion Starter #6
Ray, first off thank you for the ideas as to what it might be. The setup is basically that same as it's been for the last 5 or so years, it's my "go to" setup, you know, the one that never leaves you on the beach. At any rate, my fuel pressure gauge is 5 at idle, 6.5-7 at speeds. Timing hasn't changed, coil is good. I'm going to dig into the spring thing this week and see if that's it, hopefully not.
 
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