Fixed 96 Challenger engine died at full throttle

[Badbrp]

Ok hear I am writing this post for anyone with the same problem I had. 96 Challenger 800 single. Boat would run all day up to 5/8 throttle 5000-5500 rpm but if you opened it up 3/4 to full and got the revs up past 6000 after about 5-7 seconds engine would die as if you hit the stop button. Yes you could launch the boat full throttle then back down to cruise and all would be fine. So whats wrong fuel lines, clogged fuel filter, bad selector valve, improperly tuned carbs,
bad fuel pump, rave valves, Oil injection, ya and the list goes on. For me it was none of the above. Thing was just running out of gas plain and simple.
I'm new at this but after rebuilding the complete motor this year for a PTO failed piston, and rebuilding carbs and fuel pump, checking oil injection and fuel pressure plus an engine leak down test, all were good. So out we go and the same thing happen again, engine dies at 3/4 to full throttle. Ok rebuild the PTO only this time and Brand new carbs with fuel pump, test everything again and back out to have same problem. So you ask what the bleep is up with that.
Well hear is my answer. The manual says boat will use 12.2 gallons an hour at full throttle and thats fine on a stock motor or a .01 over one but I'm at .06 over now and also we do not have a pressurized fuel tank as do the seadoo's only an atmospheric vent on the fuel tank, that lack of pressure I believe starves the fuel pump of the little bit extra it needs to pump the 12.2 gallons an hour the motor needs since the pump on our carbs is rated at around 10 gallons an hour only.
So I bought a high volume fuel pump from mikuni rated at 16 gallons an hour and boat runs great full throttle no problem all day, did not make any carb adjustment when I put on the new fuel pump left as is to see how it ran and it was the best day of my summer.
Just think about what I said about the fuel delivery and it should make sense.

 

[vission]

Do you have the model fuel pump and maybe where you bought it in case one of us also wants to replace ours?

Thanx,

 

[Waterluvr]

The fuel pump you used is simply masking the real problem as it delivers more pressure and higher volume than the stock pump and the stock pump in good order has plenty of grunt to run any 787 at WOT all day long no matter what tank or container is supplying the fuel source.

You still haven't corrected the underlying issue, whatever that may be.

 

[Mekanix]

The problem will be your water separator O-ring I predict.

From what I've experienced, much like your issue. After 3/4 throttle I was running out of steam so to speak.

The system run's on Suction. Not pressure. So any air that can be sucked in will be a problem. A 1mm gap in that o-ring will do weird things and is masked by an external pump but also running a line directly from the pump to the reserve spout on the sender will tell you that the problem is between the sender and pump.

 

[Waterluvr]

The O-ring on the filter is always a usual suspect, as are restrictions in the selector valve and cracks in the plastic nipples where the fuel hoses connect to the tank baffle that allow air leaks.

It only takes a few minutes to separate every fuel line on the boat including the fuel pump impulse hose and vacuum test them for leaks, the entire fuel system can be completely checked in about an hour.

 

[Badbrp]

Mikuni Fuel Pump Part#53-3328

I don't want to upset anyone but I have gone through every inch of hose on that boat and replaced it all, pressure tested it, even put vacuum on it, its all good. It does not suck any air at all. Even the motor has been apart down to the last nut and bolt, pressure tested and its all good. It was simply running out of fuel that's it, no gas no go.
This is only my personal experience I have around 15 hours on the fix now and no problems, I religiously check the plugs and compression to see how the motor is and it all looks good Mag 168 Pto 170 plugs are a nice brown. I think we all just want to enjoy our stuff and I can finally get out there and enjoy it with my wife and son.