New fuel tanks, now motors will not go past 4500rpm
 

Just had both fuel tanks replaced. Now both motors will not go past 4500 rpm. They run great up till then, but when I push the throttles all the way up, nothing happens.

Could there be an anti siphon valve that is restricting fuel flow?

Thanks

Yes there could be. Do you have fuel preasure guages? If so what they doing? Were these custom made tanks or from the factory?

Jon

They are from the factory.

Then they probably have the anti siphon valve. I would try and take that out. If you can get a fuel preasure reading that will help you a ton.

Jon

Are the tubes and feeds the same diameter as the original ones? Take the check ball out of the shut off/anti-siphon valve too. If your running 450 hp or more, you need 1/2" I.D. fuel hose AT LEAST to the pump, if not to the carb splitter. Don't keep running the motors until you check these things as well as get a pressure reading from each motor because whats happening is you are leaning the motors out at high rpm...just not enough go juice, and with the carbs wide open, your totally overcoming the jettings ability to keep the mixture fairly fat.

Motors are procharged. Fuel pressure set at 7 lbs. and climbs to 15 lbs @ WOT. At this pt. boost will reach 4-5 lbs.

So you have 15 pounds of preasure when the thing bogs out?

Jon

Yes!!! It really doesn't bog out. Just that nothing happen when I push the sticks all the way up. I'll bring it to 4500, then continue to wot and nothing happens. Yestarday the starboard motor did get to 5000 but the other did not.

Is it possible that you have screens in the carb inlets? This could show high pressure on the gage but your flow rate could be down causing fuel starvation at higher rpm's.

If your fuel pressure checks out okay at WOT then you better be looking for somehting else in that tank besides gas.

Roby