Engine "bogs down" at high rpms

[MarshMarlowe196]

Took the Aquasport out today after spending every day after work last week doing the yearly maintenance on my DF140.  I was running a Racor fuel/water separator for the past few years, and I was just dumping it out periodically instead of changing it.  There was a little surface rust starting to show on the old Racor, so in a pinch I grabbed one of the $7 Attwood separators from Walmart to run for today.  My engine did something today it's never done before - it would briefly "bog down" anytime I'd push it past 5k rpm's, like there was air in the fuel line..  Could this be attributed to a low quality separator, or is that not likely?  Primer bulb never collapsed and will prime to a tight squeeze and hold pressure at low rpms.  I only use non-ethanol fuel and treat it religously with Marine StaBil.  I asked Dad if the Wally filter could be causing the problem, and he just kinda scratched his head and said "maybe".  He set aside a new Yamaha filter for me to use next time, but I just wanted to bounce this off you guys.  Thanks

[John Jones]

I was going to blame the filter until you said the bulb never collapsed.  Is the bulb between filter and motor or between filter and tank?

[MarshMarlowe196]

Between the filter and the motor

[GoneFission]

I would guess you are sucking air somewhere.  Fuel pumps will pump air before fuel every time.  Check all the connections - and you may want to remove the new filter/separator and check the gasket carefully.  It's likely the fuel pump is pulling enough fuel at idle, but when you crank it up there's too much air and not enough fuel.  At least that would be my $0.02 at this point...

[MarshMarlowe196]

Thanks CJ, that makes sense.  The mount is the original mount from the Racor filter.  I'd thought that all brands of separators were made to fit to the mounts universally, but I've been reading that might not be true.  When I installed the Wally filter, I coated the gaskets lightly with oil and torqued it on with a filter wrench, so I'm thinking it might just be a bad fit.

[Curious]

Would it bog down and stay bogged down or bog down and get back up to proper rpms after a bit?

[MarshMarlowe196]

It was a brief loss of power, maybe dropped 200 rpms for a half second, then back to normal. Did this a few times. I guess pulsation would be a better word