Ford 950 will only run with choke pulled

[Uttool]

I was mowing with my Ford 950 and things were running great. I sheared a bolt and ran to the store to buy a replacement. Came back 2 hours later and would only start with choke pulled. To keep things running well enough to mow I had to wire the choke partially pulled. Worked good for about another hour and then I lost power. What would cause this?

 

[foote2floor]

This Is a long shot but, could have the motor cooled down very quickly and a part that may have been on the verge of failing finally failed. Head gasket, cracked head, or more likely a intake manifold or intake manifold gasket that is leaking would allow more air in the motor causing it to run lean. Running with the choke partially closed cuts off part of the air allowing the motor to run at the correct air\fuel ratio.

 

[mostly_gas]

Start with the fuel system make sure you have good fuel flow up to the carb, needle valve opens not stuck
no water in fuel etc.

 

[EE_Bota]

Most times it is a partially clogged carb jet, or the float level is too low, or a leak in the path from the carb to the head.

But I don't like how it happened to you all suddenly. So, make sure that the fuel tank is vented, and gas flows freely to the carb. I'd literally start at the tank and work my way to the head. The closer you get to the head, the more the work picks up, but you may find the problem at the tank, the bowl (if present) the fuel line, the inlet strainer to the carb. If you get to the carb, try spraying carb cleaner around the joints where the carb attaches, etc to try to find carb/ manifold leaks. All that is still easier than going into the carb.

Sometimes I can fix a carb while still mounted, but usually I have to remove it to repair it. Hopefully, you will find something simple without having to go into much.

I noticed that it has an oil bath air cleaner. I'd service that cleaner to make sure the correct amount of oil is in it as that has a slight choking effect all on it's own that the carb is tuned to accept. Low oil or missing filter components will breath easier and alter things a bit.

 

[wyeguy]

Had a similar problem. Blew the carb out every which way I could and it took care of the problem. Was very sensitive to any little bit of debris (check the air filter). Had to be careful to get the throttle adjustment screws back just right.

I am the modern man...my smart phone smells of diesel & grease.

 

[Uttool]

I pulled the fuel line and it was running on the slow side. I bypassed the fuel filter and it started right up. I also pulled the little screw from the bottom of the carb (Zenith) so I 'm not sure which was the cause but she's running again. This is why I bought gas vs diesel. thanks for the advice

 

[Jerry/MT]

Either a weak spark, requiring a richer mixture, too lean a mixture setting from a wrong main set setting, blockage in the main jet or a low float level or a vacuum leak around the carb metering system, The usual culprit for the latter is leaking throttle shaft, leaking carb to manifold gasket, leaking manifold to sylinderhead/block or cracked or rust hole in the intake manifold.

 

[tomsch]

I have a similar problem but with a 21hp vtwin Briggs & Stratton. It will only run with the choke on. I have tore the carburetor apart 4 times and cleaned it real good but i am still having the same problem. Any advice to help me would be appreciated. Thanks

 

[EE_Bota]

I have a similar problem but with a 21hp vtwin Briggs & Stratton. It will only run with the choke on. I have tore the carburetor apart 4 times and cleaned it real good but i am still having the same problem. Any advice to help me would be appreciated. Thanks

As you likely know, you may have a blockage in the fuel portion or incorrect fuel bowl level or a leakage of air. Also, some severe timing issues can cause but this is unlikely.

 

[EE_Bota]

I have a similar problem but with a 21hp vtwin Briggs & Stratton. It will only run with the choke on. I have tore the carburetor apart 4 times and cleaned it real good but i am still having the same problem. Any advice to help me would be appreciated. Thanks

As you likely know, you may have a blockage in the fuel portion or incorrect fuel bowl level or a leakage of air. Also, some severe timing issues can cause but this is unlikely.

 

[tomsch]

Thank you for this information. I will have to check for leaking air. I will also check the timing. I changed fuel filters & put new gasket & o ring in carb. Needle and seat look good. I will check your other advice and see what happens.

 

[Soundguy]

to the op.. did you get the 950 going?

 

[tomsch]

No i really want to thank everyone for thier help. I decided it needs a new carb.
Thank You

 

[Soundguy]

old one really that bad?

 

[tomsch]

Yes my old one is really that bad. I really appreciate your help.

 

[pedalstomper78]

If it needs the choke to run, there's a clog in the main jet. I would assume that the tractor has either sat for a while and you have some varnish in the jet or that the fuel filter has let a chunk of junk into the fuel bowl and subsequently clogged the jet. In most cases, it shouldn't be too difficult to pull the carb off, pull the float bowl, and clean out the main jet and passage. The worst thing that you can do is jsut start turning random screws. Unfortunately, turning screws can mask a problem, but can't solve it.

Before buying a new one....take the old one apart and clean it. If there's a screw with a passage behind it, count the number of turns it takes to tighten it from the seat. When you reinstall it, tighten, then back it off the same number of turns. This should keep your settings the same.

The only real reason to replace the carb would be if the bushing that the shaft is on is worn too badly. Always rebuildable. Carbs run on some basic airflow and fuel flow principles. A better understanding of those is a better key.