Would the power valve cause the motor to act as if its running out of gas as you start to press the throttle? and somewhere between 1200 to 1500 rpm is when this occurrs, after 1500 the motor runs smooth. No one in the v-drive section answered this, any one here know? RCM
Have you checked your plugs? Bad power valve would cause a rich condition. What kinda carb? Is it a vacume secondary or mechanical? If its vacume, what spring do you have in it. Not the safest thing to do, but look down the carb as you push on the accellerator to see how much fuel is coming out of you squirter nozzle(s). If theres none you could have a ruptured accelerator pump or cloged nozzle? Could also be you accellererator pump cam?
What you are describing sounds like a lazy acc pump. What is the history of the carb? The power valve is a crutch to get through the delay in main jet flow when you nail the throttle, but the acc pump is the main player that adds the necessary fuel to go with the opening throttle bores. If you don't have it, go buy the Holley book, read it cover to cover, then address your problem as its happening with a better understanding of what is really going on...Moneypitt
PS: The secondary opening should not be proceeded by a bog, giving you the big rush as the carb recovers. If it didn't bog, you wouldn't "feel" the recovery!! should be a gradual increase in speed and RPM, not a shock...........
Moneypitt, the carb was put on the motor new last summer and it worked perfectly most of the summer , but the last time or two I took the boat out it started doing that. So this year I`ve had the boat out twice and its doing this every time I slow down and then try to throttle up it has a dead spot. RCM
RCM, take the accelerator discharge nozzle out [above the the boosters ] from the primary side ,held by a screw . Make sure not to drop the screw inside.Check the two orifice by poking with a paper clip . It sometimes gets fouled and restricting fuel delivery. If it's clean, you should see a steady stream of discharge by pushing the accelerator lever once.
With the A/f off, and the motor OFF, ollk very closly at the discharge nozzle as you JUST BARELY touch the throttle linkage. The slightest movement MUST create a squirt. If it doesn't, you have too much gap at the lever arm.(the screw with the spring around it).....OR the acc pump check ball/valve is dirty and not closing completely allowing part of the charge to leak back into the bowl, so when you push down you have to re-charge the acc circuit fully before you get the squirt. This is what you're testing by slightly moving the linkage and watching the nozzle. You should also check the duration of the squirt, but don't make habbit of sloshing all that fuel in the motor,(flooding)....Moneypitt
Moneypitt, I forgot to mention that the motor has backfired thru the carb more than once. RCM
http://www.***boat.com/forums/showth...threadid=46193
RCM,
Check out this link.
RCM,
I am guessing this is a Holley carb, they are famous for that and think there is a mod to prevent blowing it out. Ty would know.
One way I learned to check is with the idle mixture screws but has been so long can't remember if it is to turn them in all the way or adjust out, not that it would take that long to try both.
R
Originally posted by RCM
Moneypitt, I forgot to mention that the motor has backfired thru the carb more than once. RCM
RCM,
If it has experienced a through the carb backfire and your carb does not have power valve blowout protectection I would almost guarantee a blown power valve.
A blown power valve can make your engine run rich at idle and you may experience erratic idle characteristics as well. (surge)
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