300/440/550 carb problem

Austin

Austin

Location
Loveland, Colorado
I dont typicaly need help tuning and problem solving on my skiis but this one has really got me. I just bought two 440's and 2 650sx's Anyways the only one that is close to running was a 1977 440. SO I tried to get it running and I got it to were if you put some pre mix down the carb it will run until it all burns off. The problem is that the "in line" wont feed fuel to the carb. I have tried three different bn carbs and they all do the samething. I have tried different fuel lines inside, fuel cap, out side fuel cap and pressure checked the whole fuel system so I know it holds pressure. ALso replaced the one way flow on the breather. Please let me know if anyone has any ideas. Also If some one would tell me which lines go on what fittings to double check the lines are in the right places.
 
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screaming440

screaming440

The Old Skool Professor
Location
KC/Lake of The Ozarks
also the feeder is in the main carb body, the return is in the side of the fuel pump/regulator body and the pulse is in the center of the pump/regulator body.

and don't dismiss the possability that you got 3 carbs with bad fuel pumps. so if you got a vacuum pump pull a vacuum on the pulse line to check the pump diaphragm for leaks.
 
Austin

Austin

Location
Loveland, Colorado
screaming 440- I replaced the pulse line right off the bat because it was original. It also sounds like all my lines are running to the right fittings. I will post a picture of it. I think it might match one of your js's.

serio- thanks for the diagram! I will give these bn's one more try then I am going to look for some of the spacers so I can run my 44 sbn.

If any one has the intake spacer to push the intake away from the motor please let me know I could really use them!
 
N2 H2O

N2 H2O

Previously Tbone550
Location
Charlotte, NC
Are you still using the stock fuel selector switch? It could have a bad seal in it causing the carb to not be able to pull gas through the lines. Try blowing into the return line until has starts coming out of the return nipple on the carb and try to start it. Were any of the carbs you tried rebuilt? It is definitely possible that all the carb were bad if none of them were rebuilt recently.


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screaming440

screaming440

The Old Skool Professor
Location
KC/Lake of The Ozarks
Austin said:
View attachment 179119

screaming440- If I remember right you had a ski with the same color combo. If I am not coming up with stuff You should post a picture or two also year!
Click to expand...

that does look just like one of my skis but they got scallops on them not a fade like that one. painted them in 1991 and scallops where the sheet back then. one is a 1978 440 (the screaming440 cuz you have to wear ear plugs to ride it) the other is an 1982 550.

don't give up on that bn carb there is nothing wrong with them. the BN trash talking is just a bunch of fools that don't know anything about how a carb works or how to fix one so they buy a new SBN and bitch about the BN they could not fix.

there is really vary little difference between the BN and SBN. the SBN has changable jets but most of the BN problems are caused by popoff pressure problems so that change didn't fix anything.
 
screaming440

screaming440

The Old Skool Professor
Location
KC/Lake of The Ozarks
N2 H2O said:
Are you still using the stock fuel selector switch? It could have a bad seal in it causing the carb to not be able to pull gas through the lines. Try blowing into the return line until has starts coming out of the return nipple on the carb and try to start it. Were any of the carbs you tried rebuilt? It is definitely possible that all the carb were bad if none of them were rebuilt recently.


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Click to expand...

Austin i agree with tbone besure you have fuel flowing to the carb.

do this by pulling the feeder line and blowing air into the tank. if the fuel system is free of leaks and obstructions you should get a steady flow of fuel out of the line just after you stop.

the other way is to pull the feed line, remove the fuel fill cap and with a blow gun blow air in to the tank while holding a rag over the rest of the fuel fill hole to seel it. you should get a ton of fuel out of the line when you do this.

if that all works check the fuel pump with a vac pump and check popoff pressure cuz the needle valve may be stuck closed too.
 
Austin

Austin

Location
Loveland, Colorado
I am doing strait lines from the tank to the carb. I have tried blowing pressure through the on way then I will get fuel to the in line but once you try starting it and check there is any fuel, there is non. The reason I wanted to do sbn was because I have the one off of my x2 that I know works, so it was mainly to figure out if it is a carb issues. I messed with it more and I figured everything besides the carb, I know is good. But non of the carbs were on running skiis, so it could be that they all have bad pumps? I really want to just find one that I know works and go from there with it! I guess if any one has a good 44 bn laying around I might buy it. or if any one has the intake spacer for the 44.

What specific part is the fuel pump on the bn?
 
screaming440

screaming440

The Old Skool Professor
Location
KC/Lake of The Ozarks
the fuel pump is at the top of the round part of the carb. it has a plastic diphragm and check valves .

you can bet that any carb that has been sitting around needs to be rebuilt. if you try and use one you are just going to be chasing your tail.

it is not that hard to rebuild one of these and the parts are only about 40 bucks. so i would put a kit in one with a new neadle and seat. don't get an off brand kit get the Mikuni kit cuz the popoff is always way off with the junk springs they put in the kits like SBT sells.
 
j2the-e

j2the-e

Location
AZ
Is your pulse line clear? I know you replaced the hose but what about the fitting? Could be clogged with spiders.
 
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