74 40HP Norseman puking gas

[vh2q]

Well I rebuilt the carb and replaced the float with an OEM rebuild kit. Followed the manual re setting float level level upside down. First hot day hooked up gas and it came pouring out of the carb throat due to pressure in gas tank. Motor was tilted up. Set it level and then pumped the bulb. Same thing. Took bowl off (a huge pita as the starter motor has to come out), tweaked float and same thing. Repeat, adjusted float so its visually not level with the carb body, held float up and pumped bulb and it was dry; but after reassembly, same thing when I try to get hard bulb, it's coming out of the main jet tube like a geyser. Consequently motor runs for a few, then diesels and shakes and shimmys and puts out huge clouds of smoke, then it dies. Comp is 130/130. Have spark. Lower unit sitting in a trash can full of water (with plenty of what looks like black grease now floating on top). What am I missing here?

 

[F_R]

Got the clip correctly installed on the float/float valve? It does NOT go through the hole. Bowl vent plugged up? It would be hard to plug, but dirt daubers can and will do it.

 

[vh2q]

Where is the vent? I don't see any vent. The gas is coming out of the high speed tube.

Yes, clip is right not thru hole. It just clips onto the brass arm. Valve seems to work fine with the bowl off, ie it will seal up tight if I hold the float up and pump the bulb.

Had the starter motor off for the fourth time. Looked at everything again. My current theory is the (new) cork float is oversize and is hanging up on the side of the carb bowl. Not sure what to do about that

 

[oldboat1]

Float orientation as pictured: http://www.iboats.com/Carburetor/dm/cart_id.976154157--session_id.970907757--view_id.1550126 ? Main part of float above the arm goes up into the top of the carb -- if the float is upside down, maybe could hang on the bowl as you describe, leaving the float valve open.

Assuming the carb is assembled correctly, think the running issues you describe could be a fuel pump problem.

 

[F_R]

If you look at the front of the carb where the air enters, you will see one or two big holes beside the main intake. One or both of them are vents. I just have a picture in my mind to refer to without getting out the books. The point is that if air cannot get out of the bowl, fuel cannot rise in the bowl to shut off the inlet needle. Since it can't rise in the bowl, it seeks it's own level as any liquid would---which is up through the main nozzle. This is true on just about any float-fed carburetor.

 

[valvebounce]

By a process of elimination and logic,if the carb worked before your upgrade,then it's something that you have done.
I would personally start again from scratch,checking as you go,and checking the size of the new float.
Removing the jets etc,and blowing them and all the orifices in the carb through with carb cleaner would be my first move.
Once you know your jets and orifices are clear,then logically,it has to be mechanical.
Just a thought,have you checked the length of the cut off pin with your new float,it could maybe need a different pin.
Flooding is nearly always a float/pin problem,I'd recheck your float level when you reassemble just in case.

 

[vh2q]

I rebuilt the fuel pump and it's delivering fuel aplenty so that's not it. I will check the vent today as the fuel is coming out of the top of the main jet tube when I pump the bulb. It's making gurgling noises as it does so there is air coming out with the fuel. I have not had that with any other motor. Incidentally, when I took the carb off the motor that vent hole was plugged with wasp mud and I had to clean it out ... maybe not thoroughly enough. (I have never run this motor so I don't know when last it ran ... a long time ago judging from the condition of the boat!).

 

[F_R]

Aha!!!! Wasp mud aka dirt dauber mud. There ya go....

 

[vh2q]

Well I took the bowl off again and could not get air to blow through the vent passage from either side. Cleaned bowl vent passageways from both ends out carefully with drill bits. Still no air. Took little plug out to access blind passageway over the top and it was full of mud .. wasp mud. OK got that cleaned out. Put all back together. Bulb hard, no puking. But now no gas at all ... motor will not even cough. Grrr...

Does the vent passage connect with the slow air fuel passage? Maybe some of that grit got into the slow speed orifices? Still I can't get this thing to even cough on any throttle opening, with or without choke. There is gas in the bowl, I checked it via the drain plug.

Or maybe the float is now set too low? I had it a tad low when it was pouring fuel but would that cut off all fuel flow through the main jet?

 

[oldboat1]

Haven't talked about carb cleaning technique, and probably worth mentioning if you have clogging issues. Recommend full disassembly and soaking if you haven't done that -- soak and poke, and blow it out with carb cleaner (using the plastic nozzle). The domed top has to come off before soaking, and the top of the carb cleaned out. I leave the linkages attached, and soak both carb top and bottom in lacquer thinner (metal parts only). Look for passages running through the carb body, and blow those out after soaking. Take the nozzle out (#20) and soak and poke it with thin wire, and make sure the gasket (#47) is in place when reassembling.

 

[vh2q]

OK well I cleaned spark plugs, tried one more time no luck, took a break for lunch, went back out there, removed top access plug to check slow speed orifices (3) and found them clean. Put new plug in, put a dash of gas in the carb throat, and she started right up. And ran as smooth as any motor ever ran. Adjusted idle, she just purrs. Very little smoke. I have to hand it to F_R , when he said daubers I put 2 and 2 together and figured there must still be some crud in the furthest reaches of the bowl vent (and why the engineer who designed this thing made the vent so tortuous is a mystery to me .. but then again that's probably the same engineer that wants us to remove 8 bolts to get the starter motor out before we can access anything on the carb ). So for now, we are going to call it good. Will test it under load on the water in a couple of days.

 

[F_R]

The basic design of that thing dates way back to the early 1950's. It kept evolving through the years till it got to where you are. Life was simpler in 1950. Just think how bad it must be working on the 2017's. I was looking at a new Dodge Hemi a couple of weeks ago. You could not even see the engine in there.

 

[valvebounce]

Glad you found the answer,with most old motors that have been stood a while,gumming up is almost always the problem.The gas evaporates and the 2 stroke oil
eventually forms a hard glaze in the jets and orifices.Like was previously mentioned,soaking and blowing out with carb cleaner usually solves the problem.
Drill bits are not a good move,they could change the inside.dia of the jets and orifices.Fine tungsten wire works better.(here in the UK washing lines are made with tungsten wire internally)

 

[vh2q]

Went out on the water today. Started right up and purred, put a smile on my face! Could not see water outlet as it was under the water but it was putting out something. Did a couple of low speed passes all felt and sounded good, then opened the throttle. Sounded OK but no guts on WOT. Tweaked the low speed jet and tried again. Then things went South fast. First a hiccup, then knocking (hopefully it's pre-ignition and not bearing knock), shut her down, then smoke coming out of cowl. Took off cowl, heads were cooking, paint turned greenish no longer blue metallic. I just installed a new impeller and overhauled the entire lower, cleaned out everything I could access. Apparently this motor has no thermostat, it's not referenced in the manual. Where to start looking for blockage? Reluctant to remove heads as that opens up a whole new chapter. Will remove side covers but don't expect to find anything, I was just in there. Not a big deal to lower the lower unit again and check impeller but again I was just in there. I fear there is a blockage somewhere in the power head. Is there a simple way to test?

 

[hardwater fisherman]

Make sure the water tube is correctly in place on top. And be sure the key is in the impeller. An easy test to check for blockage in the power head is to take off lower unit. And using your garden hose force water through the water tube and it should gush out the exhaust relief and out through the exhaust housing.

 

[oldboat1]

exhaust outlet on the leg was under water? Think your motor is mounted too low, or you missed the class about water coming out of the vent when the cooling system is working.

Mud daubers don't have a particular preference for carbs. You may have blockages in the water passages in the head -- stuff looks like fine sand when it's flushed. It sounds like you need to take off the head cover and replace the gasket, after resurfacing the mating surface. While at it, use a small screwdriver, knife or whatever to clear out the passages. Good idea to flush as hardwater fisherman describes.

 

[vh2q]

It's true I have very little experience with outboards ... I put lack of water down to thermostat but apparently there isn't one. Took lower unit off again, made sure water tube went into pump grommet this time. May not have seated correctly last time. But when I started motor in garbage pail not getting any water stream. Should have tried garden hose trick will try that tomorrow and will take water pump apart to see what's going on in there. That's one thing I have done before so I don't think that's the problem. Although I admit there was some scoring in the housing and I didn't replace that, just the impeller.

 

[oldboat1]

would bet on a blockage, offhand -- based on your carb experience. I would do the flushing hardwater recommends before going back into the impeller.

 

[vh2q]

No Title

OK well I pulled the lower unit, hooked up a hose to water tube, and no blockage. It peed water beautifully. Turned drive shaft by hand and could hear impeller turning, making rubbery noises. So not the key. So then I took lower and put it in garbage pail up to the flange in water, hooked up hand drill to top of drive shaft using a socket and a square drive, rotated in correct direction and zilch. Took water pump housing apart and my jaw dropped. My brand new Sierra marine impeller had disintegrated. Dozens of pieces. What could cause this?

 

[hardwater fisherman]

Maybe it was run dry? If you ran it in a barrel how deep was it? The impellers for that motor are not cheap. I know because I have a 1976 40hp that uses the same one. They are NLA and around 50 dollars US. EDIT I just reread your post and you said you ran with the water up to the flange. Those pumps need to be submerged to prime. The water should be above the bulge where the pump is.