temp. loss of rpms on VMax 200 (efi not hpdi)

[JeffS]

Symptom: runs fine/normal at max throttle (5300-5400 rpms) UNTIL boat encounters boat wakes or heavy chop that causes boat to rock from side to side. Doesn't have to be a violent or hard rocking motion. Within 2-3 seconds motor will lose 500-700 rpms for the next 10-15 seconds and then quickly wind back up to 5300-5400 rpms. Does not happen while running on clean, smooth water.

Things I checked: Removed plugs, looked darker than normal and ever-so-slightly oily but otherwise OK. Replaced plugs. Examined filter cup for water & sediment. None, but replaced filter regardless.

Result: still the same symptom. Can even 'make' the rpm loss occur on smooth water by rocking the boat via steering. Same thing 10-15 seconds loss of rpms.

Ideas? Overflow inside fuel pump assembly (from a sticking float due to rocking/jarring) being dumped into the intake via the overflow hoses? Can I use vise-grips or something to temporarily pinch closed the overflow hoses and test this theory?

It is a problem that more than likely won't occur while in the shop...lack of rocking motion.

Anyone else had experience like this or have any ideas?

Thanks,

Jeff S.

[Ken]

Jeff,
I'm not familiar with the fuel injection on your motor, but it sure sounds like you have a fuel related problem.
I would first check all fuel line connections to make sure your fuel pump is not sucking air when you rock the boat side-to-side. I would also check the fuel pickup tube that sticks down into your fuel tank to make sure it still is picking up fuel off the bottom of the tank - it should be pretty close to the bottom and not up away from it. If it's not close to the bottom, it could be sucking air when the boat rocks.
Hope this helps,
Ken K
Beaumont, TX