I just bought this Yamaha YS624 Becuase out of all my snowblower's this one is on track's,and seem's like a cadilac of snow thrower's.My problem is it will only run if I spray gas in the carb.It ran great last year the old owner said,and he went to start it and service it for this year,and he had the fuel problem.If I spray gas in carb it will run fine.Im getting gas at the little diaphram block under the carb that has the fuel line running to it,and then it has on fuel line going to carb taward's the back of carb near motor,and the other vent line I would think it is.What would be a area to start replacing in.The needle valve,and carb are spotless,and working as it should.Im handycaped,and I need to get this baby running.Im on fixed income so I can't buy part's I don't need or buy part's that wont fix this proble.It a Yamaha YS624 on track's.Thank You in advance for any help on this.One other question is where is a good place to get part's?Thank You
I think you need to keep following the fuel further along the system.
If by "the block" you mean the fuel pump then the next thing you should check is the bowl. Is the fuel pump pushing fuel into the bowl? If not, the needle attached to the float may be stuck. Rather that remove the bowl to check for fuel, just remove the drain at the bottom of the bowl and see if fuel runs out. If fuel does run out, pull the crank a few times to see if the pump will push even more fuel into the bowl (that should run out of the bottom too).
At the end of every year I run my engine dry and drain the fuel bowl. The following year when I try to start, sometimes the fuel pump need to be soaked in gas for a while before it starts working again. Might be time for me to find a new fuel pump.
I took the fuel pump apart and cleaned,and carb.Where are you meaniing the main nozzle?Im green to this.I have fuel going to pump (if that's what it is under carb mounted to air cleaner with a fuel line coming from gas tank)but not going to carb.I don't know where to get part's if I need them?I greatly appreciate the help
This should be an easy fix. But be very very careful and gentle when you mess around with the float and the two metal arms holding the float, they break if you look at them the wrong way.
Do you have compressed air?
It sounds like you cleaned the carb already. When you took it apart did you unscrew and clean the main jet and the pilot jet?
What you need to do is pull the float off (very, very carefully) and blow compressed are into the hole where the needle sets. As long as you have the carb off you should clean out all the other fuel and air passages if you didn't already. Read the first post above for some tips. You carb is probably different in some ways because its a 626 not an 828
I went back out in garage today to check out the snowblower,I have gas at bowl of carb.I took needle valve out,and blew air threw it,and reassembled it,and still no gas going threw carb it seem's.With the choke on and several pull's I don't see no gas or gas fuem's in carb.?I take the bowl off with the gas line still hooked up on machine,and with carb still on machine.Doesn't seem like there gas pass the bowl?Where do I get a carb rebuild kit?Could that little square block with the fuel line running to,and the fuel line comming out of to the carb be any problem.I think it's the fuel pump correct?Im just on a super tight budget,and with x-mas,and 3 kid's im pressed for $$.Thank You again for the help.
take and remove fuel line from carb turn key off turn engine over acupple pulls does fuel pals out of fuel line. If it doesn't fill fuel tank to the top gas shoud run out of fuel line . If it doesn't there might be a clogged fuel line or shut off valve.If it does hook up fuel line try to start. You might take your left thum and block off the hole on the choke butterfly to make it choke harder wile you pull the engine over. If It starts and runs out of fuel at about 3/4 tank replace fuel pump.
Gas does puls out real good when I do that.Ive also put my thumb over choke to choke it hard,and still not a bit of gas in carb other then the bowl having gas.I want to rebuild carb so I can rule out the needle valve.Im hopping it's sticking,and im just no seeing it.I blew air threw,and it goes right threw,and that's what weird.
I never seen a kit for these carbs . I clean them out or replace them . THE main jet is scewed into the part that the float bowl is bolted to . On some carbs there is jets scewed up in the center of the carb .alot of the time i can clean out the carb without parts. I'm just real careful with the gaskets.The low speed jet is screwed straight down in carb brass scew with hole in top. remove jet there is a small hole on the other end of it about the size as of a thick hair .Good luck
You're making progress. You've figure out that the gas is making it from the tank to the fuel pump
You've confirmed that that fuel pump (black box) is pumping fuel when the strart cord is pulled.
The bowl is filling with fuel so you know the needle valve is not stuck.
You've mention that you "took needle valve out,and blew air threw it" but you didn't say if you cleaned the small hole with a thin wire and you also did not mention cleaning any of the jets. Have those been removed and cleaned already? Sorry if I'm not following you completely.
No your following me perfect!And Thank You for the help.I didn't put a peice of wire threw the hole but I did blow air threw it.At 1st it was a little hard to blow threw but after I took the needle out,and blew threw it with my compressor it seemed to be better.I did take the jet out of the top of carb,and blew air down threw that.As for the fuel in the bowl.I turned the gas off though with the bowl off the carb and it did run out at a consistint flow.So im sure the bowl is filling.On another note the thing fire's on the 1st pull with a shot of either and run's super untile I stop spraying.I don't want to give up due to $$,and this thing look's like a mean machine!!Thank you so much for your help.Can I get just a needle valve it's self?
No, I don't think that you can get the needle valve by itself. The only way I've seen it listed is with the whole carb ($).
If you have the time, you might get a can of "combustion chamber cleaner." This stuff is available at most outboard marine centers and it works a lot better than regular carb leaner.
Spend some time and really clean that carb well. Have you removed the carb from the engine or are you trying to work with it while its still in place? When I had this problem I too the carb off and soaked it over night in combustion chamber cleaner and then ran small wire (twist ties stripped of the plastic/paper coating) work really well. Pock the twist ties down all the holes and then use the compressed air to blow them out. I think its hard to really clean a carb while it is still attached (maybe you have already removed it). With the jets/nozzles removed blow the compressed air into the hole and use you finger to block the air flow and force in into the small orafices that jut off to the side. All this may seem like a bother, and to be honest if any of the other easier fixes worked I would not bother taking things to this level, but it really still sounds like you have a clog. It may be that the carb is toast but it should still start and run for you.
Fuel pump pressure doesn't matter at this point. All you care about is that the pump gets fuel into the bowl.
Once the fuel is into the bowl the low idle jet (nozzle) or the high speed jet uses the vaccum created by the suction from the engine's piston to pull the fuel and vaporize and pull that fuel into combustion chamber. If the either is working (and that stuff is rumored to be terrrible for you engine) allows the motor to run, I would still be looking at the carb.
I messed with the yamaha today again,I took carb back off,and took a bread tie wire,and ran it threw where the needle seat's,and cleaned every little bit of carb and still the same problem.I want to start replacing fuel pump,and carb.Can I buy the diaphram in fuel pump?Can I get these part's anywhere?When I pull motor over with fuel line unhooked from carb it like burp's shot's of gas out,but not a consistint flow?Snow is getting close,and im getting worried.
http://old.nabble.com/Inexpensive-replacement-diaphram-kits-for-pulse-fuel-pumps-td20026201.html#a20043271There are aftermarket fuel pumps that will do the same job for less. Ebay has them. (yamaha does not make their own fuel pump, they must outsource those). IF the fuel tank is completely full the line should gravity feed into the bowl even if the pump is bad. Remember, the pump is not presurizing the system like in a car with fuel injection. All the pump is doing is delivering fuel to the back side of the hole that that needle closes when the float lifts in bowl.
If there is gas in the bowl and its not getting sucked "up" through the nozzles then my guess is that the problem is still a clog. That our there's just not enough compression. When you hold your hand over the air intake and have someone pull the cord can you sense a fair amount of suction?
Just my 2-bits. Again, I only have the 8hp model with a different carb.
What hose is the air intake?I know the one line on bottom of pump comes from the fuel tank,and the one fuel line from pump goes to intake,and the other line is to the bowl to feed needle right?What one do I check.Can you get after market macuni carb.'s?That's what's on my machine.I have super compression too.Your carb pic.'s are almost if not the same carb configuration.Look's identicle.Your help is super appreciated.
HI supercab I think your missing the main jet. by what I've read you've cleaned the inlet float needle jet. When you remove the float bowl the tube going up the center of carb. some carbs have the main jet scewed into the side of that tube. other carb the main jet is screwed up inside that tube. if it is inside the tube be very careful that you don't tare up the theards in the tube. I've taken a wore out phillups scewdriver cut off the bad end then ground the sides to a regular standard end. the sides are rounded instead of being sharp so it don'nt harm the threads. most standard screwdrivers the sides are sharp and in a wedge shape . the low speed jet is screwed straight down in the top its brass with hole in center of it . if you remove it the very small hole on other end & on the sides is whare the fuel flows. good luck