AC G carburetor problem

FreshEarthFarms · May 9, 2016

I've been struggling with getting my G working consistently this season. I'm hoping someone can help. The latest is the carb seems to drip
gas whenever I am cranking the engine. If it just sits with the fuel line valve open it doesn't drip gas. I can get it to start
occasionally but it runs really poorly and sputters to a stop shortly after starting. Then I can't get it to restart. I assume based on the
gas dripping that the engine is flooding. I've rebuilt the carb including a new float valve and seat. I've replaced the spark plugs,
points, condenser, coil and plug wires. The float is about five years old and doesn't have any fuel in it.

Anyone have any ideas on how to get this going? It ran great last season. It ran great for two days this season but no longer.

Mike(NEOhio) · May 9, 2016

Does the bottom of the air intake tube have the drain fitting or is it plugged? If plugged it could fill with gas and block the air flow.

FreshEarthFarms · May 9, 2016

I have the air inlet disconnected while trying to diagnose the problem

Aaron SEIA · May 9, 2016

Sounds like the needle and seat aren't sealing or the float is adjusted wrong and it's not shutting the fuel off. New aftermarket needle and seats are pretty much junk from the get go.
AaronSEIA

FreshEarthFarms · May 9, 2016

I bought the kit from Yesterday's Tractors. I had the same problem using the old needle and seat and thought replacing them would fix the
problem. Any idea how to adjust the float?

FreshEarthFarms · May 9, 2016

I should also mention again that it doesn't drip when the engine isn't cranking. I would have expected it to drip continually if it was a
float/valve issue...

JoeM(GA) · May 9, 2016

from the shop manual -

The float level should be set with the float
1/4" from the top edge of the bowl or 1/4"
between the bowl gasket and the nearest edge
of the float. The idle needle is set approxi
mately 1-7/8 turns open. The float may be
set by bending very near the float axis, being
sure not to cause the float to stri'ke the edges
of the bowl.
With the engine heated to normal operating
temperature, the idl~ stop screws should be
adjusted to permit the engine to operate at
approximately 500 r .p.m. at low idle.
G - lZ

FreshEarthFarms · May 9, 2016

Thanks for the reply. I read that in the manual but I don't understand how to take the measurement. What I did was hold the top half of the carb upside down and measured the distance from the edge of the float nearest the needle to the carb top/gasket. It measured 1/4". Is that how it is supposed to be measured? I also set the idle screw to 1 7/8 turns open. Neither of these solved the starting problem or dripping problem, which may in fact be the same problem.

Mike(NEOhio) · May 10, 2016

Measure the float at a point opposite the needle and pivot. Carb upside down is the correct way. The float is generally level with the carburetor body.

FreshEarthFarms · May 10, 2016

I took apart the carb again and measured the float as suggested. It checks out at 1/4" from the body. Any other ideas?

Chris (swIA) · May 10, 2016

It's not the carb. Reinstall the old points and condenser.

FreshEarthFarms · May 10, 2016

Anyone know what the item is on the carb explosion diagram that I highlighted with the red arrow? It looks like there should be something either on the end of the jet or on the jet somewhere. I don't seem to have that on my carb if in fact it is something.

FreshEarthFarms · May 10, 2016

I'm getting good spark at the coil and all the spark plugs. What makes you think it is the points and condenser? I'll have to buy a new set since the old set is no longer with us...

Mike(NEOhio) · May 11, 2016

It's a tiny fiber washer that seals the shoulder of the jet to the body. It may be stuck up in the bore or come off with the jet. Or some PO lost it, easy to overlook.

Dick L · May 11, 2016

It sounds like the vacuum is pulling in more gas than is needed. I would look at the power jet to see if it is missing or it is not sealing on its gasket. Normally on the G the power jet is non adjustable. The idle needle is only for idle. It adjust the air in the idle circuit with fuel for smooth idle. When past idle air is pull into the engine and the fuel is adjusted to the amount of air for proper mixture. The power jet meters the amount of fuel being mixed with the air.
To rule out other problem except the carburetor whiff starting fluid into the manifold without the carburetor or thru the carburetor without gas to see if it runs on the starter fluid. The discharge tube in the neck does play a part in the mixing of the fuel with the air but excess fuel would seem to need to get by the power jet first. The only other thing would be if the choke plate was closed. This would cause the same thing. The choke plate shuts off the air to cause the vacuum to draw extra fuel to increase the amount of fuel in the mixture. When not needed it will cause gas to run out the bottom of the carburetor. As I think about it more this should have been first in my post.

Chris (swIA) · May 11, 2016

If gas only runs out after cranking it sounds more like it's flooding which sounds like weak spark. Are the plugs wet after cranking?

FreshEarthFarms · May 11, 2016

The choke plate is wide open so that's not the issue. The kit I got from Yesterday's Tractors did not include a gasket small enough to use with the jet. I didn't see a gasket when I removed the jet. Any idea where I could find a gasket? It seems like the gas would have to travel through the threads of the jet to get into the venturi. I can't see how that much fuel (based on the amount dripping out of the carb) would make it through.

I'll give the starter fluid idea a try. Thanks for the suggestions.

Dick L · May 11, 2016

I have never use my G's hard but on the old C plowing or disking it would draw a tank full of fuel thru that tiny power jet orifice in about 5 hours.

If your float valve is not over flowing the bowl and only drips gas when cranking to start then the vacuum is getting the gas from the bowl. If the bowl is not cracked the only path out is thru the power jet orifice. Some where you have an easier than normal path by the orifice. In years past I have cleaned rebuilt two of the G carburetors. Other than being aluminum they are not much different than any other no adjustable power jet carburetor. If it will run on starting fluid it would rule out a valve problem blowing back thru the carburetor.

FreshEarthFarms · May 14, 2016

If anyone is still following this I thought I would update you on the solution. Chris (swIA) was correct. The new points and condenser I installed were faulty. I replaced them with yet another new set and it runs like a new 67 year old tractor! I guess the lesson learned is to not trust new parts.

Mike(NEOhio) · May 14, 2016

Glad you found the problem. BTDT. I didn't have the gas issue you had but mine would start and quit intermittently. I was so intent on getting it started, and it seemed to want to go, I kept cranking. Right up until the smoke came out of the starter. Later I put the old condenser back in, it's still running 20+ years later. I put a set of Blue Streak points so I don't have to clean and gap them every six months.

AC G carburetor problem

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