150 oceanrunner surges, bucks rough high idle

[70amcpwr]

Same exact issue that was posted here a couple of years ago by other forum member and the end results were never posted. Mines a 2000 w/OSI. It'll run fine for almost an hour in all ranges of operation, then all of a sudden, it'll loose power and drop to headway speed with a very rough high idle and bucking, or, if just trolling the idle will spike to 1500 rpm's and be extremely rough, surge and buck. try to throttlle up and it'll shut off. Other member replaced VRO, cleaned carbs, r+r power pack, r+r stator and some other things. I'm a former marine owner and was a service manager and tech before. been through most everything. On vacation and have limited diagnostic equipment w/me, but 1700 miles away and have my tool tray anyways!

[boats.net]

Thats usually starving for fuel, try pumping primer bulb to see if runs better, try bumping choke to see if runs better. May need to remove and clean carbs and check intake gaskets.

[70amcpwr]

No change using primmer bulb. no change w/pushing primer (actually loads it up). Not carbs, runs great for extended time, 20' Pro Line WA, weight about 3k lbs, 5200 rpms and 44 mph w/ stainless prop. Boat was a recent purchase. Bypassed VRO, blocked line and capped and mixed 50:1, no change. Here's what I've found so far. Changed fuel separator, changed spark plugs (QL 78YC @ .030). Changed all fuel lines from tank to motor (primer bulb seams new and feels fine). Decarbed heavy w/Sea Foam (twice). Checked and cleaned battery terminals, checked battery voltage, 13v each (duals), cleaned terminals, checked connections on battery switch. Tested shift interrupter (works as it should). Did visual check on all connections and electrical. Found front of VRO pump was leaking oil from the urethane (square) sealant. R+R pump. Fixed oil leak. All of this slightly changed issue but all most same issue still occurred after after an hour of normal use. Todays repairs (not tested yet other than at dock, where it seems resolved). New inlet filter and seals just because. New primer cover diaphram just because (checked prior and didn't show signs of leaking). New needle and seat in VST tank. Found clear washer missing under seat and float level all messed up from last person trying to compensate for missing washer. Found VST cover warped in front enough so it would leak fuel w/engine tilted. Dealer didn't have one so I replaced rubber seal w/new and applied light coat of Form A Gasket. Disassembled Vapor pump, didn't like what I saw, round metal plate in cover beat up (con-caved) and floating around, doesn't seem right, no break down available. Bought a new one. Disassembled It. Metal plate is supposed to be secured in cover w/4 pinch tabs and flat, reassembled and installed. Replaced Optical sensor (Because it is fairly cheap and easy and sealant looked swollen). Replaced key switch because it just felt messed up and didn't have a lanyard (I unplugged it when issue was occurring so I know this wasn't the problem. Replaced seal on fuel tank sender only because it was cracked and could have been leaking water into tank (it wasn't). As I said only tested tied to dock. Top of motor (flywheel cover) gets quite hot when problem has occurred and barely gets warm at dock w/engine cover off. Will test tomorrow. So far $350 in parts and supplies plus the VRO which was $450.

[70amcpwr]

Well I paddled for 8 hours today, no just kidding! Filled up with fuel on the way out (50 gallons) and went out for a long ride. Almost full of fuel now it ran 5300 rpm's and 45 mph. Idled a lot. Ran back to speed and idled back in (20 min. in), no issues. Contined to run at dock and stop and start and still no issues. Still not certain if it's fixed but it's letting me think so for now. I'm thinking it needs a Sync and link and timing adjustment only because of the crummy work that was done previously, but @ $115/hour down here (Fort Meyers Fl) I think I'll wait until I get home and do it myself. I still have an electrical issue w/the Faria tach giving false warning lights through the diagnostic circuit. They either flicker randomly or all light up and count down as if the key was just turned on. Voltage and tach are steady as is all other gauges. It does it w/low oil tank sensor unplugged and VRO (no oil) unplugged. Gauge sounded check engine (fuel restriction) previous to changing lines when line was kinked. My guess either bad gauge or pin connection on + or- on back of gauge. Tomorrows another !

[70amcpwr]

Good news! 3 1/2 hours today and no issues. To anyone with these symptoms I would do the following:
1) Inspect VST vapor pump (see description in above post for issue). replace if questionable.
2) Inspect VST tank and cover (again, see above). replace needle and seat, cover only as needed (quite pricey and not in stock likely).
3) If problem isn't found and cured, replace Optical Sensor.
There's about $200 (without cover) worth of parts and is easy to do on water w/very basic tools. best bet is to remove entire VRO pump and bracket for that portion of the repairs and move to a bench. For the Optical sensor just Google "Johnson Optical sensor video) and the one I watched should come up.
I hope this helps someone as I searched for answers for these symptoms and found plenty of internet posts (various sites) but NOBODY post any resolved cases.