Thanks for the very good info above. Here is the update from my runs yesterday:
I cut down the fuel line by 4 1/2 feet – it was way too long in the well anyway and kind of drove me crazy…
I added some Sea Foam engine cleaner to the gas tank just to rule some gunk in there that may be causing issues.
Was able to run almost indefinitely at 19-21 MPH and definitely a bit longer at 25 MPH but it still would crap out eventually – especially if I hit wakes hard which is a behavior that I find very strange.
I had my dad drive and I sat in the back with the motor. If I occasionally pumped the fuel bulb we never had an issue and could maintain speed.
That led me to the fuel pump does not have the proper throughput to hang at full throttle. That appears to mirror what you all are saying as well…
As far as replacing the fuel pump (the suggestion above was with the Sierra 18-7351) does that unit truly fit the 30HP motor as when I go search that on the web it mentions 9.9HP or 15HP engines. Just don’t want to get under powered again. And is this a fairly simple swap out of what I have already. Having trouble completely visualizing this one installed.
Thanks again to everyone – this info is invaluable!!
Hi Rich. OK, I’ll confess I haven’t torn one of the 7351 pumps apart recently. Who knows, they might have cheapened that one too. But I’m confident it will fit your motor. Some hose re-routing will obviously be needed. And it will pump plenty of fuel for your 30hp——IF they haven’t screwed up the design inside of it.
I keyed in on your comment about the engine running poorly if cruising in choppy water, am I hearing you correctly? Some of these carbs never used the big old nozzle gasket, don’t know why. Perhaps the fuel is slopping around in there, dumping inside the nozzle well causing it to run rich. Just a “guess”. Any way of providing a video of the engine running/misbehaving?
Changed the fuel pump with the Sierra 18-7351 and took it out today. It worked perfectly. Absolutely zero issue at all speeds. Help top speed as long as I wanted to go and even sounded better from idle to max. Amazing result for $60 if you ask me.
Many thanks to this forum and @frankr for all the great advice. Pictures below of the install.
Another thing I would do is drop the sediment bowl on the carb and take out the filter cartridge , put the bowl back on and take it for a run at full throttle , I have had older snowmobiles that had the same symptoms and ran great after a new filter was installed , just another look at it
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