Secondary Venturi Pouring Gas into Second Barrel

[TravelinLight]

I took off the air cleaner to adjust the idle mixture because the FJ decided that it didn't want to idle anymore. I looked in the carb and fuel is pouring from the secondary venturi and there is black smoke coming from the tailpipe. What the hell. It is a new carb.

 

[edwjmcgrath]

Disconnect the fuel line from the return fitting on the carb. Then disconnect the fitting from the carb.
Inside the fitting you will find an orifice ( or I did on mine). Clean that orifice out.

 

[FJforty]

At least tell us what kind of carb.....

 

[Splangy]

I'm assuming you're talking about a stock carb since you didn't mention otherwise. Is the fuel coming from a vent tube or from the venturi? If it's coming from the vent tube, your float is proabably sticking (down). Check the fuel level in the float window. If it's coming from the venturi, you might have some stuck linkage somewhere.

I took off the air cleaner to adjust the idle mixture because the FJ decided that it didn't want to idle anymore. I looked in the carb and fuel is pouring from the secondary venturi and there is black smoke coming from the tailpipe. What the hell. It is a new carb.

 

[DSRTRDR]

carb solenoid working ?

 

[TravelinLight]

It's a new TrollHole carb. I hear the solenoid clicking when the ignition is turned on. The fuel is coming from the tip of the arrow in the pic below.

 

[DSRTRDR]

call Trollhole

 

[FJ40Jim]

The carb is flooding because the float bowl is drastically overfull. Probably some trash got stuck in the needle & seat.

 

[TravelinLight]

Good grief, the last thing I want to do is take this carb apart. The truck had a new gas tank, filter and cleaned out lines before the carb install. I don't know how I can make it any cleaner.

 

[FJ40Jim]

It could just be a little flake of metal that got loose when the nut was threaded on the inlet.

Sh1t happens.

 

[Pin_Head]

Try rapping on the fuel inlet with the handle of a rubber handled screw driver and see if the fuel level in the bowl window drops to half way. If it is still all the way at the top, then remove the air horn (top cover) of the carb and remove the needle valve seat and clean it out. It is not a big deal to do this, but pay attention so that you do not lose the 3 piece needle valve or the float hinge pin. Carefully remove the top cover and keep it right side up and then disassemble the top cover on a clean towel so you don't lose these parts.

 

[edwjmcgrath]

If you don't want to take the carb apart, there are a few things to try.
As I said before, I've had these carbs overfill if the return is blocked, so check out that orifice.
If that doesn't work, you can try a couple of things to clean out any junk in the needle valve. Pinhead's suggestion is worth a try. Also, you can open the needle valve all the way by draining the bowl. Pull the bowl drain plug. Then pull the fuel line. Spray a little carb cleaner where the fuel line comes in. Follow that with a little compressed air.

If none of this works you're going to have to pull the horn off or replace the carb. Pulling the horn off is easier.

 

[Mark W]

If the fuel is only coming from that point when the engine is running... make sure your secondary throttle plate is closing completely. It not, this can create this effect.


Mark...

 

[Splangy]

These carbs won't overfill if the return is blocked.

If you don't want to take the carb apart, there are a few things to try.
As I said before, I've had these carbs overfill if the return is blocked, so check out that orifice.
If that doesn't work, you can try a couple of things to clean out any junk in the needle valve. Pinhead's suggestion is worth a try. Also, you can open the needle valve all the way by draining the bowl. Pull the bowl drain plug. Then pull the fuel line. Spray a little carb cleaner where the fuel line comes in. Follow that with a little compressed air.

If none of this works you're going to have to pull the horn off or replace the carb. Pulling the horn off is easier.

 

[edwjmcgrath]

These carbs won't overfill if the return is blocked.

I had EXACTLY this problem on mine. Fuel overflowing into the secondary. After trying a few adjustments, I took the fuel lines off and noticed that the return orifice was completely blocked. I cleaned it out and reinstalled.
Fuel stopped overflowing and ran great. YMMV.

 

[Splangy]

He said it was coming out of the venturi, not the bowl vent. is that the EXACT problem you had? It sounds like you were overflowing the bowl. Also, it sounds as though you must have a problem with your needle valve (worn spring?) if you have to rely on your return flow to prevent the bowl from over filling.

I had EXACTLY this problem on mine. Fuel overflowing into the secondary. After trying a few adjustments, I took the fuel lines off and noticed that the return orifice was completely blocked. I cleaned it out and reinstalled.
Fuel stopped overflowing and ran great. YMMV.

 

[FJ40Jim]

Splangy is correct, in that the return orifice being plugged will not cause fuel pressure to overcome the needle & seat. In fact, the return port is plugged on the OP's carb because he is using a 1981 FJ45 carb w/out fuel return fitting. In a stuation where cleaning out the return fitting fixed a leaking needle & seat, it would mean that cleaning that area of the carb got the dirt out of the needle and the return orifice.

Since the booster nozzle is below the bowl vent, if the fuel level creeps up, first it will dribble out the boosters, then if fuel continues pumping into the flooded bowl, it will actually come out the bowl vents at the very top of the carb. On an engine equipped w/ mechanical fuel pump, the flooding out the nozzles will drown the engine, shutting it off before bowl level actually gets all the way up to the top.

 

[edwjmcgrath]

Here's what I know first hand. I had a new trollhole carb that was running very rich and I could see fuel dripping into the secondary at idle (I didn't look exactly where it was coming out).
After triple checking the adjustments, out of desperation I pulled the return line and found and cleared the blocked orifice. The problem immediately went away and the carb worked great.

I can't explain exactly why the return line being blocked would do that and the OP may have a different problem but it sure sounds the same and it's an easy thing to check.

 

[Pin_Head]

I can't explain exactly why the return line being blocked would do that and the OP may have a different problem but it sure sounds the same and it's an easy thing to check.

Jim's explanation is certainly correct. It is just another instance of coincidence not proving causation.

 

[TravelinLight]

Ding ding, we have a winner(s). I checked the return line but nothing was
blocking it. I then removed the air horn and disassembled the float.
The were two extremely small metal shavings (shown below) making it stick.
It is back on and running good.
Now I need to fix the Warm Pull...