Flooding when hot

[Dmcbrass]

I'm having a problem that I haven't been able to track down. My GT starts good when cold. When the engine is at normal operating temperature, I can shut it off and it will start with just a bump of the key. However, after the car sits for more than 10 minutes, it doesn't want to start. It displays what I would normally consider flooding characteristics. (The way I finally get it started is to hold the throttle wide open and crank the engine for 10 - 15 seconds. I've checked the choke and it is staying open. It looks like I'm getting fuel down into the throat of the Carb while it's sitting and I smell gasoline vapor like it's boiling; however, the car is not overheating, infact it runs cool for a GT. I have exactly the same symptoms with and without the heat shield, and outside air temperature doesn't seem to have any effect. (have seen this problem with outside temperatures of 50 F to 95 F) I have a new style Weber 32/36 carbureter on the 1.9L. I'm wondering if I may be having a float problem.
Anyone have any ideas?

[benncojr]

It sounds like the choke is not closing / opening at the right time.

What type of Carb do you have. Is it the one that moves the choke with the water temp or is it the one with the electrical hook up?

[Dmcbrass]

The choke is working correctly. The car starts fine when cold. (choke closed) And the choke is wide open when the problem is occurring.

[bozkm]

Mine does it also. I was told by my european mechanic, that this is normal. All older european cars, Jags, Triumphs, MGs, do the same thing when warm.

[Travis]

I suspect you're finding how over-rated the heat shield really is. Heat shields in general work very well in preventing heat transfer between two close items. However, as the distance increases they quickly lose their effectiveness.

When the car is off there is little to no air flow within the engine compartement and the heat from the exhaust manifold and rest of the motor quickly heats the engine compartment. Short of removing the hood, adding fans or header wrap there isn't much you can do about it. The other thing to consider is that air flow through the carb and intake manifold has stopped. This air had been helping to cool the carb and intake. Without that air flow, the heat from the head and exhaust manifold(non sprint) will conduct more easily into the carb. The steady flow of gas into the carb also helped to cool the carb while running.

I would suggest adding a phenolic carb spacer between the intake manifold and carb. This will reduce the direct heat transfer from the head/exhaust manifold through the intake to the carb. If you haven't already removed the metal fuel line over the motor, now is the time. I not only remove this line but run the new rubber line through the nose of the car to keep it away from the heat of the engine. You should also move the connection to the carb to the outboard side if you haven't already done so. If you provide the carb with cool fuel, it will require a larger rise in temperature(more heat) to cause it to boil. Obviously, if the fuel in the bowl it hot when you turn the motor off, only a small rise in temp will cause it to boil.

HTH...

-Travis

[Dmcbrass]

I think there has got to be more to this than heat. The engine is running cooler than most and I've seen this happen to this car even when the outside air temperature is as low as 50 F. I'm still suspicious of the float setting. If the fuel level was running too high in the bowl wouldn't it be more prone to boiling over?

[GTJIM]

When the motor stops the fuel pump has pressurised the fuel line so there is some fuel that can "leak" past the needle valve held closed by the float.
Check 1) that the float level is correct and 2) that the fuel valve is not leaking.
If the valve is just leaking slightly then while the motor is running fuel is being drawn away through the carb, and used. Once stopped the fuel leaking into the fuel bowl will raise the level in the bowl till the pressure in the line betwen the fuel pump and the seat drops away. Since fuel is not being used, once the motor is stopped, the fuel level will rise and tip over into the manifold. This is made worse by the heat soaking as that expands the fuel that is in the float bowl too.

[Dmcbrass]

GTJim,
That makes sense. Three questions:
1. Is there a simple way to know that the float level is set correctly on a Weber 32/36?
2. How can I tell if the needle & seat is leaking? I have a repair kit, would it make sense to just change the needle and seat.
3. I had the top off the carb a few weeks ago. Blew out jets etc. Could I have put something back together wrong to have caused the problem?

[GTJIM]

1) Have a look at the thread "Weber Troubles" of threee weeks ago - with the 'Search' facility at the top of the page.

2) Just put a new one in before setting the float level.

3) Maybe a bit of grit or lint got blown under the fuel seat while you were "cleaning" the carb??

[Travis]

If the needle valve is leaking, your motor should be running rich. Have you checked your plug color?

-Travis

[Dmcbrass]

I haven't checked the plugs, but the exhaust does smell like the car is running rich. The car runs so good that I've not had a reason to check plugs.

GTJIM,
Thanks for the advice. I'll check out the Weber link!