Fuel Pouring Out of Carburetor

[glcaines]

If I didn't have bad luck, I wouldn't have any luck at all. After I think I have solved my overheating problem on my A2 I decided to take it on an even longer drive, approximately two hours at 50 - 55 MPH because it was running so well and not overheating. When arriving back in downtown Hiawassee on the way home, the engine started missing badly and black smoke was pouring from the tailpipe. I knew instantly it was a fuel problem. I pulled off of the road into a parking lot and the engine died completely. I raised the hood and almost instantly a guy pulled in beside me. Turns out he was previously a mechanic in the Army that worked exclusively on M151s. We pulled the rubber hose from the air cleaner off and fuel poured out of the carb and hose. I checked the air cleaner and there was no fuel in the air cleaner, just oil. The guy helping me turned the starter over with the ignition switch off and I watched fuel start to pour out of the carb intake. I removed the four screws on the side of the carb to access the diaphragm and it looked perfect with no obvious damage. I put it back together. I then banged on the float bowl with a rock and then tried to start it. With the throttle wide open, the engine finally started and ran very well, including idling, with no gas exiting the intake and no black smoke. I left the air cleaner disconnected and took off for home. I made it about 12 miles, or about two miles from home, when the same issue started again. Banging on the float bowl didn't help this time, so I called my wife and we towed it home with my F250. I'm assuming here that the problem is that the needle valve isn't seating. I ordered a rebuild kit from Army Jeep Parts. The history of this A2 is that it was in storage in a warehouse ~20+ years before I got it. The newest date on the oil filter and radiator was 1992, from the Army and this 1992 date was backed up by documentation from the Army that I found in the tool box. After cleaning out the fuel tank, flushing out the fuel lines , and adding carb cleaner and fresh ethanol-free fuel, it started right up and even idled good. I didn't touch the carburetor other than replacing the fuel filters.
I've put several hundred miles on it since without a problem except for some overheating issues, which now appear to be solved. This A2 still has the original fuel pump, which is working well, but I might go ahead and replace it as well due to the age. Hopefully, rebuilding the carburetor will solve the problem.

[Hambone]

Funny it happened all of a sudden, it's common for fuel to drip out the front of the carb when trying to start, could be carb but don't rule out coil or other electrical component.

[glcaines]

Funny it happened all of a sudden, it's common for fuel to drip out the front of the carb when trying to start, could be carb but don't rule out coil or other electrical component.

I realize that it is common for fuel to drip out of the carburetor, but this was a very large amount of fuel that kept pouring out as the starter turned over the engine.

[rickf]

It is normal for gas to come out of the mouth of the carb while cranking and especially when you stop cranking. The accelerator pump is vacuum operated and every time vacuum drops it will shoot fuel out. This "Mechanic" should have known that. Keep in mind that the kits from AJP are original old stock, emphasis on OLD. The rubber and gasket material will be dry and hard. The needle tip will not handle ethanol in anything higher than 1% and even below that the ethanol will take it's toll on the needle and the accelerator pump diaphragm. Now, with all of that said I don't think the parts went bad that fast due to alcohol. The needle may be bad from age. That is why the carbs I build I use brand new kits from Zenith. They are pricey but they use modern alcohol resistant parts. When you put in the new needle and seat did you check the float settings? They almost never are the same.

[glcaines]

Rick, I haven't rebuilt the carburetor yet, I just ordered the parts kit. It is a new Zenith parts kit, not an old NOS one. Since I've owned the A2, it has never had any ethanol in the fuel. Ethanol-free fuel is readily available where I live and drive. I've rebuilt a lot of carburetors in the past, so setting the float height will not be a problem for me.

[m3a1]

Just spitballing here. Fuel return line plugged or missing altogether?

[rickf]

Fuel return is NOT a fuel return! It is a vapor return to prevent vapor lock. Yes it does pass a tiny bit of gas due to the hole in the plug but it is not enough gas to lower fuel pressure at all. Hence the fact that you can block that off altogether and it will not make a bit of difference to the barb, The pump develops 3-5 lbs. of pressure no matter what. There are hundreds of A1's running around with the 13660 carb on them with no return.

[glcaines]

I just went out and started the A2 again with the air cleaner hose disconnected. It started right up, running smoothly for about 15 seconds and then fuel started pouring out of the carburetor again and black smoke out the exhaust, and then it died. There is no doubt that I have a carburetor problem. I'm actually amazed at how much fuel will come gushing out. My new Zenith carburetor kit is supposed to arrive Monday. I'm not going to remove or dismantle the carburetor until I have the new parts in hand.

[rickf]

Be sure to check fuel pressure at the carb. You could have a pump with a diaphragm that is getting hard.

And be sure to change your oil, I guarantee it has gas in it from the extreme flooding.

[lpcoating]

What is the kit number from Zenith? How does it compare to the Norfar kit?

Guy

[rickf]

Same kit and you can only buy it from Norfar. I dealt directly with Zenith through Norfar to get them to include the emulsion jet gasket for the 13660 carb which was never in the kits.

[glcaines]

Great news! I rebuilt the carburetor and that solved the problem. No more fuel pouring out of the carburetor. I mounted the rebuilt carburetor, started the engine and it idled perfectly and smoothly. Although I didn't smell any gas in the crankcase oil, I changed it anyway just to be sure with Classic Castrol 20W-40. I took it for a ~50 mile drive and it seems to have more power than previously. Also, no overheating at all and the ambient temp was high. Apparently, my pressure washing the engine block and head did the trick since the radiator shop said the inside of the radiator looked almost new with no plugging. I purposely pushed it, trying to make it overheat, but the temp gauge stayed right where it should be. Now I have a dependable A2, at least for now, until another problem surfaces.
EDIT: I meant Castrol Classic 20W-50, not 20W-40.

[m3a1]

Congratulations! So glad to hear this worked out for you.

[rickf]

God to hear. Oil is a personal thing but most people with older vehicles will use 15W-40 diesel motor oil. It has higher amounts of sulfur and Phosphorus that will keep the lifters alive longer than modern oils that had all that removed because "It harms the catalytic converter".

[glcaines]

God to hear. Oil is a personal thing but most people with older vehicles will use 15W-40 diesel motor oil. It has higher amounts of sulfur and Phosphorus that will keep the lifters alive longer than modern oils that had all that removed because "It harms the catalytic converter".

The Castrol "Classic" oils are designed for older cars without catalytic converters and also still have zinc and phosphorus, etc. in it. I can't find it anywhere where I live and have to order it online. I've been using it in all of my older cars, MGB and older British motorcycles.