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why do I have to pump it?

pug288

pug288

New member
I got a 454 bored 60 over it's running a 850 holly. When I am getting the boat out of the water to get on plane if I pump the thottle it jumps out of the water. If I don't pump it takes twice as long. When I run wide open if I pump I will gain around 5 mph or more. What do I need to check nobody knows around here.
 
At first I was thinking weak accelerator pump, but now im leaning to changing the jets on the carb. Might need to go up a size.
 
Is this a new issues or has it always been like this with that engine/carb setup? Could be accl. pump as mateman suggested, could be jet issue or poss. stuck float in bowl.
 
Every time you pump it you're getting a shot of fuel out of the accelerator pump if it runs that much better with a shot of gas you are starving it for fuel

If this is a new carb your setup is not close, if everything is the same start looking for fuel gremlins, fuel pressure, change the fuel filters in the carb, needle and seat needs to be gone over those will corrode over winter with our lovely new gas plus on a Holley those won't sit in gas
thats where I'd start odds are the ethanol got you
 
Thinking about it, checking your fuel pressure might be the first thing to check along with your filters and fuel lines.
 
It's a crappy time of year now but I would pull it off and send it to Nickerson or one of their competitors in the fall I'm pretty happy with my aed carbs it really sounds like the whole carb has to be rebuilt maybe even see if a buddy w another 850 would let you swap for a day to know for sure
 
Hey out of curiosity can you post up a pic of your carb there was a fuel return line on the quadra jets that I've seen a lot of guys hook up to a vacuum port on the holleys that is supposed to be blocked off When they get switched in causes a similar situation to yours
 
My guess is the jetting is wrong for the engine. My theory is based on the fact that if you pump there actually is enough gas in the bowl to fill the accelerator pump to jump up in speed. If there were insufficient fuel flow/pressure then the bowl would be empty and pumping it would do nothing (we had a 19' Baja jet boat powered by a 454 with a partially clogged fuel tube that would just get to 3k and then do nothing.)
 
I've always set the float levels with the boat in the water, (had to go back and reset them a few times in the past). Other than being bored 60 over, are there any other modifications to the engine? The reason being, is this the right carb for your set up.
 
1st a 850 is a bit large for a 468 in a boat...a 750 would work much better...I would buy a new stock holley 750DP and roll on...if you keep the 850 needs to be dialed in...but not worth the wasting fuel on that engine...remember a HP500 merc was a 502 with big cam only used a 800
 
Ok I have look at carb. and I have figured out I don't have an idea what I am doing. I have called everyone I know and all have been a no show to help or have been just to busy. I've got one more guy that might look at it. My question is if I can't get any body to look at it, if I buy anouther carb will I need to get it adjusted or will it come ready to go. What kind of carb would be best? The Holly is nice but is there one better. Demons or good I have heard but I look and they cost ALOT.
 
If you buy an already modified carb from a place like Nickerson or aed they will ask you questions about your setup and generally they dial it in pretty close right out of the box you could also send yours out to be done but honestly it just sounds like yours needs to be setup properly did you look into that vacuum line I mentioned earlier also have you had backfiring out of the carb, your floats could also be not setup properly which is a very easy fix a neat trick I learned to get them very close is to take the carb off the motor pull the bowls off and turn the carb upside down then adjust the floats with the big screw and the locknut till they are parallel with the topside of the carb
 
No back firing at all. It seems there is a dead spot when I take off real slow at about 3500 to 4000 rpm. I will check the vac. line next time I climb in it.
 
pug288 said:
No back firing at all. It seems there is a dead spot when I take off real slow at about 3500 to 4000 rpm. I will check the vac. line next time I climb in it.
Click to expand...

Only takes once I was thinking more like shot power valves no fuel enrichment circuit dead spot in the power band just thinking out loud I'm far from a carb expert
 
I put size 37 accerator jet in. That is two sizes bigger. It run good on a test run but will know when I get a boat load of people.
 
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