Farmall 400 Rebuilt Carb floods, will not start

pmarkel

Member
Seeking advice on a frustrating carb rebuild on my 400. I rebuilt the ih carb on my 400 after the tractor repeatedly failed to start, with the carb flooding each time. However, it seems I have not corrected the problem because the carb continues to flood and the tractor will not start. I crank it a few times and it drips from the drip hole at the base of the carb. I have inspected the float valve and it seems to be functional (with the gas on and the bottom half of the carb removed, I manually lift the float up to level and the float valve shuts off the gas flow). I also inspected the float level and set it to the 1 5/16" that the service manual recommends. The only explanation I can think of is that the float is snagging inside the carb, thus not allowing it to rise in the bowl. Is there anything else that could explain the continued flooding? Any advice is welcome.

-Pete Markel
 

Sounds like you need to find the no start problem first.

They all drip when cranked and no start..............
 
A collapsed intake hose at the carb, a float that is filled with gasoline, or a plugged up air cleaner can do it. Put a small vinyl hose in the carb drain plug
and see what the float level is actually doing. Hold the hose up higher than the top of the carb, and it will indicate the level. Jim
 
Thanks for the advice. I had inspected the float when I soaked everything during the rebuild and the float didnt seem to leak. I hadn't thought about the air-cleaner being clogged though. Thank you.
 
Your blaming the carb, but are you sure it is not the ignition that is causing the no start? Check for
spark at the plug wires. After cranking 3-4 rounds with the choke on all Farmall of that type will
drip from the drain. If you take the intake hose off the carb and dry out the extra gas does it start
dripping again just siting there? If so then you have a carb problem.
 
Sounds like from your statement you havent checked fire at the plugs instead of thinking carb. What fire does it have and are the wires and firing order correct do you have fire at the points is there voltae at the coil lots of things to check before playing with the carb.
 
(quoted from post at 17:13:39 10/09/16) Sounds like from your statement you havent checked fire at the plugs instead of thinking carb. What fire does it have and are the wires and firing order correct do you have fire at the points is there voltae at the coil lots of things to check before playing with the carb.
he simple answer is no, I haven't checked those things. I bought the tractor in July and it ran pretty well at the time. The guy I bought it from had just changed the points and the tractor started right up. I had no intention of playing with anything. Then on the third day I owned it the starter went. So I had that rebuilt, and rebuilt again, and rebuilt a 3rd time until it was right. Then it kept stalling out while in use. First on the road, then in the yard. The carb kept flooding when I attempted to start it. So I decided to tackle the carb first.
 
I had a similar problem with a Farmall H this Summer. Found that the float had a very small amount iof fluid (assume gadoline but never
assume) in it. Laid the float aside ten weeks ago and you can still hear the fluid in the float. Not saying that that's your problem but if you have
the carb apart again remove the float and shake it close to your ear and listen for any sloshing.
 
just because he put new stuff in doesent mean it has spark you have to assume nothing if theres gas at the carb engine will start if theres spark at the plugs so you know you have gas.
 
Take a close look at the float valve. Especially at the tip. The viton rubber tips have been known to partially pull away from the brass, causing the valve to stick open.
 
(quoted from post at 20:22:56 10/09/16) just because he put new stuff in doesent mean it has spark you have to assume nothing if theres gas at the carb engine will start if theres spark at the plugs so you know you have gas.
hank you for the advice, how would I check if the coil is working properly?
 
use a dry wooden cloths pin or two to hold the coil wire (pulled out of the distributor cap) and hold it 1/4" away from the block while it is cranked. a 1/4"
crisp blue spark is necessary. Jim
 
(quoted from post at 15:33:41 10/10/16) use a dry wooden cloths pin or two to hold the coil wire (pulled out of the distributor cap) and hold it 1/4" away from the block while it is cranked. a 1/4"
crisp blue spark is necessary. Jim
hank you Jim, would I ground each spark plug wire similarly in order to test spark from the plugs?
 
I swapped out the coil on the tractor for a 12v one that I had taken off another tractor when I switched it over to a solid state ignition. It still wouldn't fire up so tmrw I'll check to see if theres spark. If not the coil or the carb, what would be the next culprit?
 
If you have spark to ground from the center wire, then its appropriate to pull off one of the four plug boots and try the same thing.

I would also take off the distributor cap and look at the rotor. If there's green crud built up there it can inhibit proper spark. I usually gently scrape this away with a pocketknife or utility knife.
 

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