70hp chrysler lose of power at more than 1/4 throttle

[joesboater]

Hi all, I'm new to boating. I just bought a 1969 thunderbird tri hull and it needs some work but i love it. The motor is a 1972 chrysler 70hp from what I'm told. Ok heres the deal I took the boat home cleaned the fuel lines, hooked up the water hose and she started right up to my surprise idled well rpms came up fine. So the next day i took her to the lake. Got her on the water tried to start her had a little trouble she was flooded but got her started put her in gear and was off she did good at low speed in the wake zone got past the wake zone rolled on the throttle slow she picked up speed till about 1/4 throttle and then died out. I started her back up took it out of gear rolling on the throttle and the rpm came up fine put it back in gear rolled on the throttle same thing ANY ADVICE?

 

[bman1bpm]

Re: 70hp chrysler lose of power at more than 1/4 throttle

I'd suggest rebuilding the carbs and replacing the fuel pump, both are pretty easy to do and won't break the bank if you do it yourself. Also check to be sure that the butterflys in the carbs actually open all the way when the throttle is a WOT

 

[maxum247]

Re: 70hp chrysler lose of power at more than 1/4 throttle

Check tank for trash, pickup tube in tank blocked, make sure it's not plugged up. If you have a portable tank make sure the vent on the tank is open.
Check fuel line for leaks, primer bulb should stay tight when hooked to the engine.
These things could cause the engine to starve for fuel and bogg down as if running out of gas!
Then do the same thing over again each time the engine was restarted.