[Dmcbrass]

I've got an odd problem that I haven't been able to solve. I thought maybe someone out there has had a similar experience. My 1970 GT with a weber 32/36 Starts good when cold. If I turn the car off after driving it for a few miles, it will start easily. Just need to bump the key. However, if I leave the car for a few minutes, (no more than 4 or 5), the car acts like it is flooded. I need to hold the throttle wide open and crank for several seconds before it starts. I also smell gasoline. Any takers?

 

[oldopelguy]

probably is flooded

It probably is flooded, as in all the gas in the now hot carb boiled over into the intake manifold and flooded out the motor. Are you running any sort of heat barrier between the carb and manifold?

 

[GTJIM (R.I.P.)]

Heat!

Sounds like the engine and exhaust heat is boiling the fuel in the carb fuel bowl and filing the inlet manifold and air cleaner with vapourised fuel - that is why the smell and the "flooding" symptoms.

Have you got the stock heat shield under the Weber carb?

One way to help is to pop the hood to let things cool down when you stop, letting some air flow up through the engine bay to cool things.

It is also not helped by "winter" fuel with higher volatility for starting in the cold being used till it runs out in your tank and a the gas stations when the daily temperature has warmed up.

That "petrol smell" means there is flammable fuel vapour about so you should at least pop the hood and let it blow away before restarting the car.

 

[Dmcbrass]

I am running the heat shield; however, I have a cracked exhaust manifold that might be raising the engine compartment temperature. the manifold is cracked across one of the corners of the flange where the exhaust pipe bolts up. It also has at least one other of the bolt holes stripped. I know that it is leaking some because I am beginning to smell exhaust when driving with the windows down. I'm planning to replace the exhaust/intake manifold next month. My first priority is to replace the rear axle with one from my 1973 parts car.
Do you think this manifold problem could be causing the symptoms I mentioned?

 

[GTJIM (R.I.P.)]

Gasp!

I know that it is leaking some because I am beginning to smell exhaust when driving with the windows down. I'm planning to replace the exhaust/intake manifold next month. My first priority is to replace the rear axle with one from my 1973 parts car.
Do you think this manifold problem could be causing the symptoms I mentioned?

The other symptoms it will cause are: Nausea, Vomiting and DEATH!

Please fix it before driving the car anymore.

 

[Dmcbrass]

There's not that much exhaust. Barely can smell it and surprisingly it only occurs with the window open. The GT is my to town and back car. 12 mi. - 20 minute trips. Would this leak cause the other symptoms (gas smell after being parked for 4 minutes and the hard start)?

 

[GTJIM (R.I.P.)]

There's not that much exhaust. Barely can smell it and surprisingly it only occurs with the window open. The GT is my to town and back car. 12 mi. - 20 minute trips. Would this leak cause the other symptoms (gas smell after being parked for 4 minutes and the hard start)?

It will certainly not help as the leak is high temperature gas that will increase the under-hood temperature and make the fuel boiling problem worse.

Exhaust gas leaks are killers since the driver gets used to the smell and the Carbon Monoxide builds up in the bloodstream day by day - POISONING YOU!

 

[baz]

fuel fires kill but you can see them
CO1/CO2 leaks kill and you dont see it

just a case of how you want to go and can you leave me the car in the will

a little exaust putty will cut the manifold leeks down as a temp fix just work it in when cold run the engine at idle for a few seconds then let the putty set hard

you may want to warm the car and let it sit 5 min then look down the carb with a flash light to see if you have apool of fuel in the manifold collector
if so you have ether no plastic spacer between the manifold and carb, and its boilong over into the carb or a leak from the float bowl and are loosing fuel that way

 

[stevyz]

weber problem` flooding into secondary at idle and after you shut it off HELP!!

ive had lot of these carbs(DGAS) never had this happen before ...fuel dribbling into the secondary (even with fuel hose disconnected) i also installed return line with 3 prong filter. I HAVE THE SPACER INSTALLED AND THE HEAT SHIELD..at idle raw fuel is dribbling into the closed secondary...i replaced the power valve and economiser....i saw bubbles coming up inside the bowl from the secondary jet.fuel percolates constant into secondary.... THERES NO PERCOLATION INTO THE PRIMARY AT ALL..
IT IS ALL GOING INTO SECONDARY LIQUID FUEL
I REPLACED THE NEEDLE AND SEAT ALSO..IVE ADJUSTED THE FLOAT LEVEL TO THE POINT IT WAS TOO LOW UNDER HIGH SPEED AND WOULD RUN GOOD (NO PERCOLATION AT IDLE) BUT WOULD RUN OUT OF GAS UNDER HIGH DEMAND..IM THINKING THERE IS A CRACK IN THE HOUSING/? BUT COULDNT SEE ANY EVIDENCE could this be caused by sinking float? it seemed ok not heavy or fuel logged.. im stumped..
ANYONE?:banghead:

 

[stevyz]

problem seems solved??

i HAVE A PILE OF JUNK WEBERS so i I SWAPPED THE emulsion tube (SECONDARY)AND THE FLOAT.. in my gut I SUSPECT THE FLOAT WAS SINKING,,,``i hate it when you fix a problem but not exactly sure how it happened...lol i will see how it does on the road in traffic and under normal driving..running real nice now..we will see if it lasts
...

update i think the secondary linkage was bent a little and the secondary throttle plate was sticking open slightly i think this may be the culprit i bent it so it now works smoothly and closes every time.... so far so good ill drive it tomorrow in the heat of the day and see how it goes..

 

[stevyz]

no such luck still doing the same thing ugh help!! gas is too expensive to waste

i HAVE A PILE OF JUNK WEBERS so i I SWAPPED THE emulsion tube (SECONDARY)AND THE FLOAT.. in my gut I SUSPECT THE FLOAT WAS SINKING,,,``i hate it when you fix a problem but not exactly sure how it happened...lol i will see how it does on the road in traffic and under normal driving..running real nice now..we will see if it lasts
...

update i think the secondary linkage was bent a little and the secondary throttle plate was sticking open slightly i think this may be the culprit i bent it so it now works smoothly and closes every time.... so far so good ill drive it tomorrow in the heat of the day and see how it goes..

I INSTALLED a new spacer still IM OUT OF IDEAS... KEEPS PUSHING FUEL INTO THE SECONDARY

 

[hrcollinsjr]

Are all of your Weber parts from that particular Weber or could a few parts been swapped around?

Harold

P.S. Fuel pressure checked and what needle and seat size are you running?

 

[Timbo]

Have you checked the fuel pressure? At some point, an electric pump was installed in my car. I plan on checking fuel pressure when I install my new Weber to make sure it is below 4 psi. The secondary could just be the weak point if the carb sees too much fuel pressure.

Just a thought.

Tim

 

[stevyz]

i dont think its fuel pressure heres why

well i had same thought first thing i did was replace the fuel filter with return line going back to the tank..made no difefrence at all .. in fact it seemed worse also i removed the fuel hose there was no pressure there and it still kept percolating the fuel out of the bowl..

 

[stevyz]

Are all of your Weber parts from that particular Weber or could a few parts been swapped around?

Harold

P.S. Fuel pressure checked and what needle and seat size are you running?

its the smaller needle i think... i bought a kit last year its the one that came in the kit..new gaskets and spacer,heatshield installed,


who knows on the parts original or not everything seemed like unmolested(till i got in there)

 

[stevyz]

photos

Pictures of carb setup.

 

[hrcollinsjr]

I'm not a fan of extreme rerouting of the fuel line but sometimes you do what you have to do. At the least I would run the fuel line like the factory did which was on the outside of the thermostat housing. Some have run it in front of the radiator and around. Not sure this will even help your situation though. I would consider insulating the heater hose that runs between the valve cover and the carb.

Anyone else want to offer a suggestion?

Harold

 

[wrench459 (R.I.P.)]

Anyone else want to offer a suggestion?

Get rid of the heat stove!

 

[West Coast GT]

I had the same problem with fuel percolating up and into the venturi. Vapor lock was also an issue.

Rerouting the fuel line in front of the radiator helped the vapor lock.

But more importantly, re-installing the original style mechanical fan and shroud directed an air flow past the carb. Boil-over immediately became a non-issue. Fuel bowl temperatures following a drive in hot weather (with the hood closed and the engine shut off) dropped significantly.

It appears from your photo you may have removed the fan in favor of an electric pusher fan. If so, try re-installing the mech fan and shroud. At least for the hot weather. Looks like you've had mid-80 degrees the last couple days.

Perhaps the reason only the secondary circuit seems effected may be attributed to that bowl being located closer to the engine. Your primary bowl may be in a thermal shadow.

 

[RallyBob]

Get rid of the heat stove!

Sprint manifold FTW!