Carb?

I own a 2000 Moomba Kamberra. I took it out a couple of weeks ago and the boat struggled to start. Once I got it going it wouldn't idle, so I kept it in neutral and the throttle down a bit. It was really smokey and ran rough. Could this be the carb? We had it out a couple of weeks before that and it ran great.

Holley carb? Check the power valve! By smokey do you mean kinda a black smoke?

Edit: Did it back fire through the carb when this issue started?

(Message edited by peter_c on February 17, 2010)

Sounds like a stuck choke. I'm guessing is has an electric fuel pump, so that leaves out a ruptured diaphragm.

Yes, Holley carb - 4 barrel.

it was black smoke.

put in a new electric fuel pump last year.

My buddy said it might be the stuck choke too?

Any suggestions? he said that I might tap it with something???

oh, also, not back firing through carb that was noticed. it just seemed like it would run if I kept the rpms high, but it was rough and smokey. If i pulled it back down it would die.

Its loading up for some reason. Stuck choke like earlier mentioned is probably the cause. Next time out check that the choke plate is open after it warms up.

Check float level,possible trash in the needle and seat,power valve. I would turn the key on so the fuel pump will run not the engine. Look in side the front two barrels and see if fuel is dripping.

Power valves are the single most common reason for that. Check the choke it is easy to look down the carb with it running and see if the choke is open. You can pull the plug out from the side an check the fuel level for a stuck float or damaged needle/seat.

Next time you run it. Put the throttle at about 3000 -3500 and see if it smooths out. If it does then you are just dumping to much fuel. peter is correct Holley's are known for blowing power valves.

Peter, no sight plugs on every 4160 I've seen.

power valve is not the problem the newer carbs come anti backfire devices to protect the power valve.It does sound like carb problems though.most common is a condition called VD venchuri discharge.with engine running at idle look in to the carb if you see fuel dripping down the barrel it's VD and time for a rebuild

I like a stuck float, especially if it was fine when you put it away. Be careful looking down the carb on a engine that isn't running right. Taking a backfire in the face is a bad deal. Preferably wear some eye protection, if not a face shield when working on a running carb'd engine.

Any way you look at it, it sounds like the carb is coming apart.

High Jack.

I've got 2 stroke jetskis ( carbed) that run fine at idle and high speed, but in order to get them to run at high speed you have to pull the choke which kills the motor, then restart, and it will run like a scalded ape. I have to do this almost every time coming off plane. one is worse thatn the other. Almsot liekt he bowls are not filling with fuel???

The carb still has a power valve and they can fail without having ever seen a backfire. I did some research on the model that Steve says it is. Seems like they made some improvements to it. The two bent tubes at the top of the float bowls going into the carb should be the overflow for the float bowls. So if the problem is the float level or a leaking seat it should easily be seen coming out these tubes.

Thanks Evan for reminding everyone to keep stupid at bay.

" ... stupid at bay." ?!?!?

Mr. Bay is stupid there now?

I sure hope you don't take offense to a commonly used saying.

I take offense to it like some to the r-word.

It's use is only morally defensible if limited to 'able-minded people' and within the 'satire' exception.

http://www.thedailyshow.com/watch/mon-february-8-2010/back-in-black---the-r-word

Sam (wake1823)

what ski's? your pop off pressure sounds wrong on the carb

is is called venturi

take the flame arrestor off and look for dripping fuel

always when you rebuild the carb, never soak them in carb cleaner, marine carbs have a special sealer on them to keep moisture out of them. Also replace the fuel filters and clean the spark plugs and look at the cap and rotor

Holleys are also know to air leak around the throttle shafts

to test, spray carb cleaner around the shaft when motor running at idle

if it picks up RPM, you have a leak!!!

Just from the tech corner, if you have a 4160 holley carb and have not used the vessel in some time, most likely the needle is not sealing at the seat (even a piece of corrosion) will do it.
not to mention the E10 problems that are starting to plaque our industry. to diognose the problem, apply water to feed under boat set choke
by pushing accelorator down once return to idle position push or pull out button, set to desired fast idle and start remove spark arrestor let engine warm up put helm control to idle, look down airhorn at venturi's if you see fuel coming from these at idle your float level has become to high a rebiuld is the remedy. have a qualified
technician rebuild it. holley carbs are the most
advanced american carbs as with amarica there are
t.s.b. technical service bullitens "be aware"
as for some coating to prohibit moisture on the carbs that bull. and worn throttle shafts yah if was a 1984. you must use a genuine holley marine kit and power valve check kit installed if it does not have one. ta ta

The two vent tubes are bent down for a reason
"marine only" application so if the floats stick open the overflow of fuel will food out the engine,& not run everywhere and ignite by a spark
thus having an explosion and the picnic is over.
cold tanks are fine for carb cleaning, also a fuel water separator system is a must, E10 E10 ta ta

i visit this thread out of curiosity because, long time ago, i tried to re-build a carb on my own. fail.

mine was on an 8 cyl '73 chevy. it had a spaghetti-work of all these oddly bent linkage rods. (along all sides ??? iirc.) the goal was to re-bend those rods to adjust the output travel of the output ends to be at certain points for certain points of the input ends. could not do.

it looked nothing like that Holley. that Holley is clean looking, seemingly free of all the linkages

holleys are e-z to rebuild, you can get to everything, cept power valves, without removing the carb from motor

yes there is a coating on the carbs

call mallory marine and ask


so why was the HOLLEY carbs recalled in 2002-2006???

hey stay in your books but stay out of the garage. guys like you make me a lot of money. ta ta

just-in-time...they are 97 yamaha waveraiders...one is the triple carb 1200 the other is dual carb 760 I think?

SAM

yes rebuild the carbs

if you want the service manuals, email me

Yamaha manuals are not the greatest, because they were translated from Japaneese

DAVE
if your quoting me, not very cool as an owner of a marine dealer

Justin I am not quoting you, its just the 4160 has been in marine use since the v8, I myself have o/h over 100 since it is such a popular carb
everyone seems to know a little something about them some more than others, manuals tsb's recalls
just look at these blogs it's a famous carb
but in my 20 years there have been numerous times
the diy says hay I just went through that carb or
just had it done by a mechanic ya there is one on every corner, ya see my point, even manuals are wrong sometimes. no hard feelings. Dave

Yes same carb on my 351 Bronco, better then the 4 barrel quad jet

The best book on that carb is the PCM manual or the holley carb itself

no hard feelings, i though you were referring to me, LOL

these newer holley's were recalled because they are made in china now, and they used tin inside the carb vs zinc!, LOL

Spray/clean well with carb cleaner. Run a can of Sea Foam through. S/b good to go. I just went through this with my 1998 Moomba.

spraying carb cleaner in a carb does absolutely nothing except maybe clean the piston tops of carbon

the seafoam might help out

"spraying carb cleaner in a carb does absolutely nothing"

I beg to differ. It will clean spooge off choke shaft and associated linkages and thus help if the problem is in fact a poorly operating choke mechanism.

A can of carb cleaner and a can of Sea Foam before any carb rebuilding is definitely the route to take.

Ockham's Razor!

still that does nothing

when you rebuild the carb, you take car of it

it is the internals that you want to clean

"even manuals are wrong sometimes" Man aint that the truth. Dont tell that to someone who believes everything has to be done "by the book". Spraying carb cleaner does plenty. It works great for free-ing up sticky and dirty linkage, which sometimes is the problem.

Sparkels

right out of the HOLLEY book
they make the carb, no way they are wrong, that is why they do service bulletins
if they were they would be sued!

"Experienced technicians develop their own order or method of disassembly" With that statement they are even saying you don't have to do it by the book. By the book is a suggested method NOT the only method.

Justin: and your point is what? That carb and choke cleaner still does "nothing". Thats it I'm going to sue the liars that sell it! LOL

what im saying about carb cleaner is

spraying down throat does nothing internally to the carb, that is where the varnish resides