Engine cutting out
 

Well, I had a real enjoyable weekend on the Mississippi. Things got kinda rough there on the way back. A bunch of cruisers were throwing some really big wakes. Not exactly LOTO water, but there were some huge rollers. Well everytime the boat went airborn the engine would lay down. When the boat would land the engine would be sputtering and missing. Sometimes it wouldn't be too bad, once I almost fell off of plane before it came back. I'm thinking that the issue is fuel related and that I'm dumping excess fuel in when in the rough. Currently the floats are set level with the plugs and the fuel pressure is at 8psi. Other than this one complaint, the engine runs like a top. Does anybody have some suggestions? Anybody experience this problem before?

Oh, by the way, the carb is Holly 850.

Does that carb have the vent splash tubes installed in the metering plates? Mine used to act like that in rough water until I put those in.

Are you talking about jet extensions? It's a little tube that pushes into the jet to extend it further into the bowl. I'm not familiar with vent extensions.

Tim, take the breather off, do you have two J shaped tubes coming out of the vents? The J shape keeps fuel from splashing into the vents. Or try adjusting the floats a bit.

No, these are plastic rectangular tubes that attach to the top of the metering blocks (vent) and extend into the float chamber. Ill try and get a picture tonight when I get home.

The J tubes keep all fuel spashing out of the vents directed into the carb. This is part of what makes a carb USCG approved. If you think you are getting fuel spashing up the vent, try putting a 2" piece of rubber hose on the tube and run it again. Make sure the hose fits tight so you don't "swallow" it.

Recheck the the float level, also check to see if you have plastic or brass floats. My Holley 830s came though with plastic floats, changing them to brass floats solved the problem. Haven't seen this problem on my 1050 dominators.

If I remember correctly, the carb doesn't have the J tubes. It has the standard slash cut vents. I do recall a tip about putting a piece of hose over the vents thus tying them together. Well, hopfully that'll solve the problem. Thanks for the help guys!

The purpose of the J-tubes (external) is to direct any overflow from the float chambers down the throat of the carbs. I dont think this had anything to do with your problem Cord. The float chamber vent splash tubes are internal and altogether different.

Oh, you're talking about those little rectangular plastic tubes. I thought the carb had them, but I'd have to check to make sure they still exist.

Yup, those are the critters. I though all Marine Holleys had them and I think they are really needed with big waves and such.

Oh yeah!! Those!! Yeah, if you don't have those in there Tim, it would do just about what you're talking about. I know mine has them, I've had my carb apart enough times to know this!!!! LOL!!!

Ok, as a quickie fix I hacked the j tubes off and connected them with a rubber hose. The first time I tried to start the engine, it flooded and had raw fuel dripping from the throttle shafts. I put a small notch into the hose and it solved the flooding problem. The hose seems to have reduced the flooding, but it has not eliminated it.

I tried to check the float levels and they seemed to be high. I pulled the pulgs out and fuel would dribble out of the holes. I lowered the float level (by turning the screw in) but could not stop the fuel dribble. I reduced the fuel pressure to 6psi with no change. I just came back in from replacing the needles and seats. No change. I also put some clear plugs in and I can see that the fuel is over the top. The needles are still screwed all the way in. Where do I go now?

Oh, yea...those retangular vent tubes are in place.

It is definitly sounding like the float level. Lower it till the fuel is just about level with the hole.
If you only turned the screw that doesnt lower or raise the level. What the screw does is lock the hex nut under it. The hex nut lowers and raises the level. Back out the screw and then turn the nut for up or down, then retighten the screw.

Dan

I was actually refering to the hex nut even though I was calling it a screw. If I take the hex nut off, I see the flat sided float needle assembly. If I turn assembly in so it's flush with the top of the bowl, a small amount of fuel dribbles out. If I back it out of the bowl a couple of turns, a small amount of fuel still dribbles out. Now that I have the plugs back in, the bowl fuel level is too high. Even with the correct fuel pressure and new needles, I can't seem to control the fuel level.

This is happening to both bowls. The floats are plastic and sound dry when I shake them.

I have never had any luck with plastic floats in a boat especially. You may want to check or replace your needle seats. You can pull them without removing the bowls. I have had trouble with 'O" rings on seat assembly's cause trouble you describe also. My guess is "O" ring or needle seat leaking by. Oh yea did I say junk the plastic floats. :D Let us know what you finally find is the trouble.

I had the plastic floats in my 830s, always had trouble until I replaced them with brass floats. Like paradigm said, get'em out.

I'm having the mrs pick up two new floats as we speak. How are they absorbing the fuel? I checked the floats and they were dry.

paradigm-I already replaced the needle and seat assuming that they were not sealing.