Rebuilt carb... Now won't start.

[55'Fleetwin7.5]

1957 35hp Lark, Rebuilt carb, kept old float (looked very good). New hoses, new gaskets, packing etc. Put it back on and tried to start.... I tried a few times until I got a strong gas smell. would not fire. I pulled the plugs and they were dry. A little bit of gas leaked from the bottom of the air silencer... ( I figure that was coming back through the system unburned)... I did noticed that the manual choke was out (thus overriding the choke button I was pushing) AND since I had disconnected the throttle cable earlier... the throttle position was "slow" not "start"... I let it sit for about thirty minutes and went to try again... I still smelled gas and it would not start. I put the manual choke "in" first and made sure that the throttle was on "start". I have my high and low needles turned out about 3/4 from seated. Any thoughts? It ran great before I fixed it.

Tom

 

[jbjennings]

Re: Rebuilt carb... Now won't start.

Hey Tom,
Take that darned air silencer off until you get it adjusted close on the high and low speed needles. Also, look for a lot of fuel pushing out your carb throat in case the float isn't shutting off the needle valve and fuel is pouring out. Also, if you just had the throttle on slow instead of start, that's probably your problem. You need the throttle advanced as far as it will go with the motor in NEUTRAL. Make sure it's in neutral and the forward lockout mechanism is working. Then give it a shot. I'll bet it will crank with the choke on. If not, give it a shot of premix sprayed into the carb throat now that you have the air silencer off and see if it will crank.
Just some things to try,
JBJ

 

[noelm]

Re: Rebuilt carb... Now won't start.

OK, lets start at the beginning, was it going before you pulled the carby to bits?? if yes, then do not start pulling other things to bits as well, because you are going to end with some other faults as well (maybe) fix the carby properly, if it did not go before hand, then you need to figure out why, do some very simple troubleshooting, does it have spark, does it have compression, eliminate all possibiliies one by one, so not pull a dozen things to bits!

 

[phipps]

Re: Rebuilt carb... Now won't start.

Maybe you dont have the low speed needle turned out far enough. On my motor the low speed initial setting is 2 1/2 turns from seated.

 

[freddyray21]

Re: Rebuilt carb... Now won't start.

the problem I've seen recently is the high speed jet either not cleaned out as good as you thought or the gasket for same jet not sealing properly. You do need to have the throttle opened more as already stated and premix down the throat will see if it will fire.

 

[55'Fleetwin7.5]

Re: Rebuilt carb... Now won't start.

OK, lets start at the beginning, was it going before you pulled the carby to bits?? if yes, then do not start pulling other things to bits as well, because you are going to end with some other faults as well (maybe) fix the carby properly, if it did not go before hand, then you need to figure out why, do some very simple troubleshooting, does it have spark, does it have compression, eliminate all possibiliies one by one, so not pull a dozen things to bits!

This motor was sitting since 1968. I rebuilt the ignition and lower unit then it did start. I felt that it was appropriate to service the carb because of the length of time it sat and all the hoses were dry and brittle. All else functioned well.

 

[55'Fleetwin7.5]

Re: Rebuilt carb... Now won't start.

Hey Tom,
Take that darned air silencer off until you get it adjusted close on the high and low speed needles. Also, look for a lot of fuel pushing out your carb throat in case the float isn't shutting off the needle valve and fuel is pouring out. Also, if you just had the throttle on slow instead of start, that's probably your problem. You need the throttle advanced as far as it will go with the motor in NEUTRAL. Make sure it's in neutral and the forward lockout mechanism is working. Then give it a shot. I'll bet it will crank with the choke on. If not, give it a shot of premix sprayed into the carb throat now that you have the air silencer off and see if it will crank.
Just some things to try,
JBJ

Excellent advice re: the silencer! I will look for gas coming out of the throat. How many turns from seated are suggested low / high? Obviously, I will need to remove the needles AGAIN to get the silencer back on... but at least I will know what the settings will be. Also, does anyone know about synchronizing carbs with ignition? I have never done that before... what is required for this?

 

[55'Fleetwin7.5]

Re: Rebuilt carb... Now won't start.

the problem I've seen recently is the high speed jet either not cleaned out as good as you thought or the gasket for same jet not sealing properly. You do need to have the throttle opened more as already stated and premix down the throat will see if it will fire.

Carb was surgically clean! I even removed the welsh plug and cleaned out that chamber. What kind or "premix" do you mean auto starter fluid?

 

[wbeaton]

Re: Rebuilt carb... Now won't start.

Gas pouring out the carb usually suggests a float needle not seating or the float not set properly. However, since you also floaded the heck out of it maybe a half hour wasn't long enough to wait. The initial settings should be about 1.5 turns on low and 1 turn on high. Some say 1 1/4 and 3/4. It doesn't matter. Just something close to that is fine. I'd try it again before committing to a second cleaning/rebuild.

Someone will also mention that a sinking float will cause your problem and that those old cork floats are notorious for that. Since your motor just sat for 40 years I doubt that is what has happened. Of course, you should reseal or replace that float just the same.

Premix in a spray bottle is just that. Mix up 24:1 gas-oil in a bottle.

 

[tashasdaddy]

Re: Rebuilt carb... Now won't start.

i have never had a problem after i started using Joe Reeves, method, get it close in a barrel, then take it to the river.

(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle va /lve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, wating for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

 

[55'Fleetwin7.5]

Re: Rebuilt carb... Now won't start.

This morning, with both needles seated... I turned it over and it started "briefly" not in a tank yet. I put it in a tank, turned the needles out 1 turn each... flooded. gas coming from the throat. Took carb off and replaced the cork float with plastic one (could not get it to level as it drops too low and hits the float valve seat assembly. I tried bending it up a bit. I also removed the little retaining wire for the float valve that came with the "Sierra" kit. None was there before. Put it back on and it flooded again "through the choke valve". I think this "the float valve/float" is the key problem area... agreed?

Also, a question. The float sits around the "high speed nozzle". Is there a large washer that should go on that nozzle? I don't remember taking one off, but a firend said that one of the washers from the "sierra' kit was for that spot. It seemed about the right size, made of cork/rubber, I just don't remeber one being there.

Thanks for all your assistance with this. I have rebuilt four carbs before on smaller motors and they all went well... I hope this will be fixable too.

Tom

 

[catalyst-519]

Re: Rebuilt carb... Now won't start.

This may be overly simple, but I just rebuilt a '64 5hp and had the exact same problem. I actually had the float on upside down so the needle wouldn't seat properly. Rather than bending the new float, which shouldn't need to be done did you try turning it on the other side?

Good luck.

 

[55'Fleetwin7.5]

Re: Rebuilt carb... Now won't start.

Well I used the same "attitude" as the old one. It had a small tang that stuck downward. It does seem a tad smaller in the inner circumference and hits the area where the small needle is seated. Something to consider.

Again... does anyone know if a washer needs to go on the valve tha sits right in the center of the float when it is installed? I don't remember one being there, but a friend said it might be necessary and there was one about that size in the kit... I don't see one in my parts list... Any thoughts?

 

[freddyray21]

Re: Rebuilt carb... Now won't start.

Well I used the same "attitude" as the old one. It had a small tang that stuck downward. It does seem a tad smaller in the inner circumference and hits the area where the small needle is seated. Something to consider.

Again... does anyone know if a washer needs to go on the valve tha sits right in the center of the float when it is installed? I don't remember one being there, but a friend said it might be necessary and there was one about that size in the kit... I don't see one in my parts list... Any thoughts?

see my post above. The gasket you refer to does go on the valve. That is the main jet. Did you take it out and clean it? Without a gasket on there sealing it to the bowl it will suck air not fuel and will not run.

 

[freddyray21]

Re: Rebuilt carb... Now won't start.

Carb was surgically clean! I even removed the welsh plug and cleaned out that chamber. What kind or "premix" do you mean auto starter fluid?

never use starting fluid. get some 24:1 in a spray.

 

[55'Fleetwin7.5]

Re: Rebuilt carb... Now won't start.

see my post above. The gasket you refer to does go on the valve. That is the main jet. Did you take it out and clean it? Without a gasket on there sealing it to the bowl it will suck air not fuel and will not run.

I guess I am stumped because I cannot find it on any of the diagrams for my motor... It would be listed as a part, would it not? It is still in place and making a good seal.

 

[freddyray21]

Re: Rebuilt carb... Now won't start.

if the carb is off and upright you should be able to blow air into it through the gas line. If it is upside down you should not be able to blow any air. That will tell you if the float is working. I don't adjust the float level with the tang (maybe I should) I bend the float arm to make the adjustment. While you don't want it so low it will not close or two high so it wont' open or let enough gas in for it to run at wot there is some variance. Ideally it should sit level when the carb is upside down.

 

[freddyray21]

Re: Rebuilt carb... Now won't start.

don't have your diagram, but it's on all of my manuals. It is necessary for it to seal. It just sits on the jet. The end of the jet sits in the bowl in the center and the gasket seals against the lip there.

 

[55'Fleetwin7.5]

Re: Rebuilt carb... Now won't start.

On my first attempt, I did blow air to check and it was closed. I guess something may have changed after I closed it up. Very frustrating! I leveled the original cork float. I am going to see if maybe the small needle they sent was different from the original...

Thanks guys, I really appreciate the help.

 

[freddyray21]

Re: Rebuilt carb... Now won't start.

doubt it is the needle being wrong. while you have it apart check the gasket to the main. I have found some of the sierra kit to have a gasket that is too thin and does not seal right. I have been making them from gas hose with a razor blade myself.