Carburetor help!

[ruby23m]

Got the boat on the hose to do the spring checklist and ran into a few problems...
I overhauled my Holley 4160 carb last fall and had the boat out a few times after. I went through the carb because the engine would die after bringing to idle speed from cruise and then would not want to start after. I noticed while on the driveway yesterday that when I would shut the boat off, fuel was still being dumped into the engine for 10-20 seconds after. I know that shouldn't happen and was wondering if this was part of the reason I was having problems last year when bringing the boat to idle after cruising. Is there a float adjustment you can do? Is this likely the reason I have no problem starting the boat cold, but then dies coming down from cruising?

Also... I am not sure I put the choke assembly back together correctly- it does not close when starting cold and in fact starts easier if I manually engage it.

Any suggestions will help, I am just getting to know how to adjust things, my first 3 years with the boat I haven't had to do anything related to fuel delivery!

[matt k]

I'm not a carb ninja or anything, but generally if fuel is dumping out of the venturi when it shouldn't be, it's either because the floats are set too high, have sunk, or the float valve is not closing, either because it's worn or damaged, or because some junk got in there and is keeping it from closing completely.

To adjust the floats, you pull off the fuel bowls and bend the little tab that contacts the valve (it takes VERY small bends to move the float height)

As far as the choke, do you have the wires on in the right place? I believe if you reverse them, it doesn't work right, but I'm not 100% sure on that.

[86 century]

On the holleys the float ajustment is the screw on top of the bowl.

No need to pull the anything apart.

If the a float is stuck the fuel will dump out of the bowl vents.
The power valve will dump out like you are holding it wide open.

[joel210]

Not to thread jack, but....

I have the exact same problem on my 89' sunsport with a holley on the 351. Boat ran great first time out for the first 1 hour or so, but when I came back down to idle speed from cruise, the boat stalled out. I pulled the float bowls off drained the fuel, tried to see if the floats were stuck,put it back together. Idled great, but same thing once brought the throttle back off cruise to idle. It looked like it should be at full throttle with the fuel dumping out in to the carb and flooding it. Can I just replace the power valves? The shop wants about $350 for a rebuild, but I think it has to be a simple cheap part. It was rebuilt 3 years ago and probably only 100 hours put on since. Any advice, I have never pulled a carb apart, but mechanically somewhat inclined.

[Jetlink]

I will never understand why shops are quoting $350 for a carb rebuild. Hell, for less than that, I can go buy a brand new carb off the shelf that has been zero timed and sit this one on the shelf and rebuild it on my own at my own pace.

[joel210]

agree.Also a rebuild kit is like $40, so I don't know where the extra $300 plus come from.

I hate to mess with the whole carb since the engine runs perfect, except for this new little quirk it has. Hoping this problem fixed before the weekend.

[OUI]

The 4160 does not have an external float adjustment. You have to take the float bowl off, turn it upside town and make sure the float lever is at a 90 degree angle. If not, bend it to a 90 degree angle.

[joel210]

thank you, I'll check it out tomorrow. I'll take some pics to show you, just to see if something doesn't look right.

[matt k]

i just rebuilt mine as well. From everything I've read, fuel dumping out of the venturis when it shouldn't is a clogged float valve, a float set too high, or a damaged/worn out float valve. I can make mine do that very easily by setting the floats a little too high, and make it stop by setting them just a tiny bit lower.

[kvand347]

i just rebuilt mine as well. From everything I've read, fuel dumping out of the venturis when it shouldn't is a clogged float valve, a float set too high, or a damaged/worn out float valve. I can make mine do that very easily by setting the floats a little too high, and make it stop by setting them just a tiny bit lower.

Matt,

How close is your float to being level when turned upside down? I know that is the recommended initial adjustment.

[matt k]

at the moment, it is set to "eyeballed" level when inverted. This leads to a slight fuel drip from the venturis. Like, one drop every 10 seconds, and only on the passenger-side venturi kind of a thing. When I get around to it, I will adjust the float down by a hair, and that should take care of it.

I got this from a holley manual:


Dry Setting for Duracon Side Hung Float:
The primary side setting is .2188" (7/32"), measured with
the fuel bowl inverted, at the toe of the float. The secondary
side setting is .3125" (5/16"), measured with the fuel bowl
inverted, at the toe of the float.

But when I do that, I get a lot of fuel leaking through both venturis. Also, since the "toe" of the float is curved, I really have no idea where those measurements are supposed to be made.

[matt k]

Oh, also, joel, power valves are cheap and easy to replace, might as well give that a shot.

For anybody who's going to be in and out of the carb a lot, i like the "non stick" blue gaskets holley makes, and a bit of pam cooking spray or similar stuff will also help keep your gaskets intact

[DAFF]

There is a learning curve to setting the float. To make sure the float is the issue you could start up the boat run it for a few seconds pinch off the fuel line keeping the RPM's up for about a min then back off the throttle to idle. If it runs beter and doesn't stall out then the float is the cause of the grief 100%.

I don't think you are far off on the float. You could use the trial and error method .... Just keep adjusting the float needle valve so it closes faster WRT the float untill she runs good.

[kvand347]

at the moment, it is set to "eyeballed" level when inverted. This leads to a slight fuel drip from the venturis. Like, one drop every 10 seconds, and only on the passenger-side venturi kind of a thing. When I get around to it, I will adjust the float down by a hair, and that should take care of it.

I got this from a holley manual:


But when I do that, I get a lot of fuel leaking through both venturis. Also, since the "toe" of the float is curved, I really have no idea where those measurements are supposed to be made.

Keep in mind that the measurements Holley recommends is for a carb that is sitting level in a vehicle. You are running a carb in a boat that is not sitting level...especially if you have a 1:1 trans. I believe the 1.23:1 trans allows the engine to sit more level in the boat.

[joel210]

Well, I am not carb checked out. So I just pulled it off, found a shop that will take a look at it and replace what is needed to be replaced. But I has been a prob atleast 4 years since a rebuild, and it looks like they have used crapy paper gaskets. Looks like there are better gaskets on the market now. I'll post what they find out, it goes in on tuesday.

[ruby23m]

I took off the bowl and bent the tab, it did look like it needed an adjustment. Fired her up and shut it down several times with no more leaking. Now need to vet out on the water to see if that was the issue last year. Will post when i get her out!