I think its a fuel problem?

[jetboat=$]

454 , holley carb.
my problem is when i have my boat full throttle for a period of time and i go to let off. the motor wants to stall. i have to pump the throttle in order to keep it going. can be pretty scarry at times. any suggestions?

[Duane HTP]

yes, let off easily or install a dash pot like the old fords had.

[77charger]

what fuel pump?-should be in good shape wheter mech or elec.
what is fuel pressure?-too high could overcome floats and flood or not enought to keep carbs fed.
are floats set correctly?-if too high it could be dumping too much fuel,too low not enough fuel

[jetboat=$]

good place to start. sounds like a very cheap fix. its funny, it doesnt spit or spudder, it instantly just dies if i let completely of the throttle.

[SmokinLowriderSS]

Sounds weird. I have a 454 and a 700 CFM Holley atop it, no such trouble. Are you certain you do not have any vaccume leaks? They could cause such. Does strike me as maybe a low float fuel level. As asked earlier, what is your WOT fuel pressure? I had a mechanical pump go bad that would be fine @ idle but couldn't flow enough to maintain any usable power levels.

[jetboat=$]

Not sure at this time what fuel pressure is. Boats in storage. But what do you feel adequate fuel pressure is? what number range should i look for?

[roostwear]

Your throttle blades are too closed at idle. Sounds stupid, but think about it.... if you slam them shut with no air to provide a signal.... no fuel! Try either opening up the primary and/or secondary throttle blades .020" or drilling an air bypass hole in the primary throttle blades, then readjusting your idle mixture. You'll probably wind up leaning out your idle a bit (turning the screws clockwise, but it's no big deal unless you uncover too much of the transition slot in the primaries.

[Wicked Performance Boats]

Turn your holley upside down and look for a tiny set screw next to the secondary throttle bore. turn it in and the throttle blades will open up a little. reinstall and adjust idle. Budlight

[jetboat=$]

how is this going to effect my idle? to high? to low?

[sanger rat]

Sounds like you have fuel spilling out the rear vent tube and flooding the motor.

[Moneypitt]

Sounds like you have fuel spilling out the rear vent tube and flooding the motor.
This is a possibilty. Use a short piece of fuel line, 1/4 inch, about 6" long. Push it over the bowl vents, both pri and sec. Loop the hose up to the aircleaner stud and cut a slot it the upper most section,(only the top side of the tube) about 1/2" long, secure to the stud with cable tie. This raises the point where fuel can spill into the carb. Try your boat, if it still does it, it is not from spilling over and flooding the engine. If it cures it, you're done. Another thing to remember, at WOT you are dumping alot of fuel in the engine, to suddenly stop all air from entering a fully packed intake manifold will create a vacuum signal nightmare. After it dies does it re start right away? Does it blow black smoke when it does start? If the hose trick above doesn't help, try a 1/2 in turn on the throttle stop, (idle speed adjustment) and see if that helps....One other place to look is the power valve, at WOT the vacuum is low and the power valve would be adding fuel, so suddenly closing the butterflys would also close the power valve and COULD create a lean condition as the venturi would also quit flowing fuel through the main jets, and the engine is still slowing down. Just a few ideas,(guesses)......good luck......MP

[jetboat=$]

it will start right back up without any problems(no smoke, no hesitation)

[beerjet]

hey jet , mine would do the same thing but mine didnt have a regulator when I bought it so I slapped one on her and set it 7 1/2 psi and it got rid of the stall and fuel comin out of the vent tubes if thats your problem
beerjets .02

[77charger]

Not sure at this time what fuel pressure is. Boats in storage. But what do you feel adequate fuel pressure is? what number range should i look for?
at least 5 no more than 7.After 7 you could overcome the floats and flood motor.Less than 5 you could have starvation problems.Most unregulated pumps will have between 5 and 7psi.The high performance ones will have up to 14pounds

[SmokinLowriderSS]

My mech fuel pump runs 5-6 at idle, right at or just above 9 stretched out wide open.

[Wicked Performance Boats]

how is this going to effect my idle? to high? to low?
It'll raise it 100 to 300 rpm. Just lower the idle screw and readjust your idle mixture screws. BL

[Jim Hall]

This has happened to me a few times but it was not related to a fuel problem. It has happened when running wot and I get out of it real quick for instance hitting a wake coming out of the water and then back again loading the pump when motor is almost idle it has stalled. I know it's not good for pump shaft but it does happen ocasionally.

[SmokinLowriderSS]

When Lowrider gets accidentally airborne and I pedal her, I try not to back off more than about 1/2 to 2/3 way. I try not to slam the throttles completely shut from WFO.

[sleekcrafter]

Any chance you may have water in your fuel? I have had water in one of my tanks before, acts like a fuel starvation flow restriction at first notice.
Sleek