Weber Hard Start Warm Problem

[JSTOLLE]

My 1970 GT with a weber 32/36 Starts good when cold and runs and idles fine. However, if I drive it for a while and it gets warm and I leave the car for a few minutes, the car acts like it is flooded. I need to hold the throttle wide open and crank for several seconds before it starts (if it starts). I also smell gasoline. So- took the air filter off and I can see raw fuel gurgling into the primary- 2 or 3 drops every couple of seconds when everything is off. I'm a novice mechanic but that can't be good can it? Any help as to how to stop this would be appreciated. The carb is new, the engine is rebuilt and I have put the wireloom insulation around the fuel line and plastic fuel filter after reading about heat problems. Any other things ideas? Thanks.

[opellane]

I have a Weber 38 DGES on my GT, I use to have that problem too, But since I re-routed the fuel line under the car away from any heat source and added OGTS Electric Fuel pump, near the fuel tank. (blank plate where Mech. pump was) I haven't had that problem in years, starts first crank after being driven. These cars are known for vapor lock. (under hood temp gets very hot after you turn off motor) A preasurized fuel line is hard to have vapor lock.
Just my .02 cents worth, works for me.

[newman27]

... I have put the wireloom insulation around the fuel line and plastic fuel filter after reading about heat problems. Any other things ideas? Thanks.

If you have metal fuel lines running from the fuel pump to the carb across the front of the engine, even covering the fuel line with an insulator isn't always enough. Switching to a rubber fuel line all the way was the only way I could get rid of the vapor lock issue completely given the very hot temps here in Atlanta. I hated to give up the nice looking stainless steel fuel lines I had but had no choice in this hot weather. Finally, the vent lines from the gas tank can also affect fuel flow. If they are clogged, a vacuum is created that restricts fuel flow until it has had time to "dissipate" through the gas cap or some other outlet which may take some time.

HTH

Matt

[JSTOLLE]

Thanks for the ideas. I will try these starting (of course) with the easiest (and cheapest) first to see how it goes. It's usually not too hot here in Minnesoata, but it sure is hot under that hood! Thanks Again guys.

[wrench459]

Sounds like a fuel foaming problem to me.
Vapor lock is the fuel boiling before the fuel pump.
Fuel foaming happens in the carb bowl adding pressure on the jets.
The solution is to try all of the above then try..
thicker carb spacer
heat shield
Blower across the intake
A electric supply pump with a with a return line to cool the fuel.
The more the alcohol content of the fuel the more problems you'll have in the summer.
See "reed vapor"
Hope this helps

[BMWonly]

Since your carb is dumping gas down the throttle, I don't think you have a vapor lock problem (not enough gas due to air bubbles). I suggest checking correct float bowl level (41/51mm).
I just installed a brand new 38 Weber with the same symptoms, and the float bowl adjustment fixed it (besides rejetting for optimal throttle response).

Dieter

[JSTOLLE]

Thanks-Good ideas. In Minnesoata we live in the land of ethanol so that is probably contributing to the problem.

[73Manta72gt]

If you see liquid fuel in the carb. at idle you have a flooding problem, maybe a new needle valve, float level wrong, float with gas in it, etc. sounds like it's hard to start due to an over rich mixture on a hot engine.

[JSTOLLE]

You got it on the rich flooding part. But, this is not at idle. Car idles fine. It's after driving it when it sits for a couple of minutes. Then the fuel just starts percolating into the primary chamber. It's a new Weber 32/36 carb from OGTS and today I just rerouted the fuel line around the hot part of the engine way up in front of the radiator. That went fine, but it still does it. I hope it's an adjustmnet issue as you all say here...float level etc. That's my next step. Tks.

[dcm013]

You got it on the rich flooding part. But, this is not at idle. Car idles fine. It's after driving it when it sits for a couple of minutes. Then the fuel just starts percolating into the primary chamber. It's a new Weber 32/36 carb from OGTS and today I just rerouted the fuel line around the hot part of the engine way up in front of the radiator. That went fine, but it still does it. I hope it's an adjustmnet issue as you all say here...float level etc. That's my next step. Tks.

Both my Opels (71 GT and 74 Manta) have the same issue, but they never fail to restart. Both have Webers. Plus, if they idle for extended time (say more than 5 min) they want to stall unless I keep blipping the throttle. Fuel boils in the carb since it sits right over the exhaust manifold. I have the thick carb gasket, heat shield, wrapped the fuel lines, and even re-routed the Manta's fuel line well away from heat with rubber fuel line.

I'm in MI where we have 10 percent ethanol in all the gas and I'm convinced this (and maybe other fuel additives they don't tell us about) is the cause. I do find some improvement if I burn premium. A sprint manifold would probably help, but hard to find and costly. Fuel injection would no doubt eliminate the problem all together. Today's gas ain't what it used to be.

Don

[Dale .D]

Both my Opels (71 GT and 74 Manta) have the same issue, but they never fail to restart. Both have Webers. Plus, if they idle for extended time (say more than 5 min) they want to stall unless I keep blipping the throttle. Fuel boils in the carb since it sits right over the exhaust manifold. I have the thick carb gasket, heat shield, wrapped the fuel lines, and even re-routed the Manta's fuel line well away from heat with rubber fuel line.

I'm in MI where we have 10 percent ethanol in all the gas and I'm convinced this (and maybe other fuel additives they don't tell us about) is the cause. I do find some improvement if I burn premium. A sprint manifold would probably help, but hard to find and costly. Fuel injection would no doubt eliminate the problem all together. Today's gas ain't what it used to be.

Don

This might be a winter project but you can convert your exsisting exaust manifold to a sprint type yourself.The info is in here somewhere.The heat riser I don't think is benificial & you could take out the heat sheild too.Just another place for a vacuum leak.Good thread!

[tomking]

Both my Opels (71 GT and 74 Manta) have the same issue, but they never fail to restart. Both have Webers. Plus, if they idle for extended time (say more than 5 min) they want to stall unless I keep blipping the throttle. Fuel boils in the carb since it sits right over the exhaust manifold. I have the thick carb gasket, heat shield, wrapped the fuel lines, and even re-routed the Manta's fuel line well away from heat with rubber fuel line.

I'm in MI where we have 10 percent ethanol in all the gas and I'm convinced this (and maybe other fuel additives they don't tell us about) is the cause. I do find some improvement if I burn premium. A sprint manifold would probably help, but hard to find and costly. Fuel injection would no doubt eliminate the problem all together. Today's gas ain't what it used to be.

Don

This is why I separate the manifolds and weld a cover plate over the cut off exhaust manifold, making the modified sprint.

[Dennis Texas]

My 1970 GT with a weber 32/36 Starts good when cold and runs and idles fine. However, if I drive it for a while and it gets warm and I leave the car for a few minutes, the car acts like it is flooded. I need to hold the throttle wide open and crank for several seconds before it starts (if it starts). I also smell gasoline. :

I'm sure you have already checked to be sure the auto choke is opening as it warms up, other than that and the suggestions of rerouting gas line I would go with wrong float setting?

[JSTOLLE]

I had a carb guy look at it today and he said that simply put it's too hot under there. He says the fuel is boiling and the accelerator pump jet is the one that is dripping the most into the chamber. He suggested 2 things...(1) try non-oxy fuel (like you suggest DCM). Sounds like you've found the premium might have an even lower boiling point. He also suggested a blower fan (boat vent type) mounted up front in the void space and then ducted back to the carb. I seem to remember that in these forums and will check this out. I'll also study the sprint manifold as a Winter project too as suggested. Thanks from Minnesota. The good news here is that it's mostly WINTER most of the time!

[Dale .D]

Great to hear your getting closer.I hear good things about the aluminum radiators reducing temperatures.I'm not in a real hot area either (Vancouver Island BC) but with 30 degree celcius plus temps right now i have no overheating fuel problem.I have the sprint & didn't use the heat sheild. 160 degree thurmostat. keep us posted.

[dcm013]

I had a carb guy look at it today and he said that simply put it's too hot under there. He says the fuel is boiling and the accelerator pump jet is the one that is dripping the most into the chamber. He suggested 2 things...(1) try non-oxy fuel (like you suggest DCM). Sounds like you've found the premium might have an even lower boiling point. He also suggested a blower fan (boat vent type) mounted up front in the void space and then ducted back to the carb. I seem to remember that in these forums and will check this out. I'll also study the sprint manifold as a Winter project too as suggested. Thanks from Minnesota. The good news here is that it's mostly WINTER most of the time!

I think it was Otto that had pictures of the fan and duct setup from a Datsun 280Z he runs on his injected GT. It mounts to the top of the valve cover.

I hadn't thought about a boat vent fan but it sounds like it may work. I've got the stock air cleaner on my GT so I'm not sure where the ducting would fit. Lots more space on the Manta - I can pull air in through the original cold air intake in the grill. What about a temp. sensor to turn it on only when needed and a timer to run it for a bit after shutdown?

Don

[bigjim5551212]

I think your choke is coming on too fast. I mean, the choke goes on, when the engine is still relatively warm. You need to loosten the 3 screws holding on the choke housing and make it so the choke plates have some resistance when you push on them when the engine is off and the choke is cold.

[Nathan Acree]

You might also check into getting a phenolic (a composite material) spacer. The spacer insulates the bottom of the carb from the intake manifold and can make a huge difference if you are experiencing the fuel boiling problem. Generally though if the intake manifold is getting that hot there is usually another problem.

You might also see that you are not running way rich or have you timing way advanced causing your exhaust to get really hot due to burning fuel entering the exhaust manifold.

Nathan Acree
Albuquerque New Mexico

[wrench459]

More possible solutions to think about.
Lower T-stat
Heat shield
Change of fuel stations believe it or not
Back in the early 80's or late 70's Chrysler had a rubber carb to intake spacer on the 2.2's. Bet its impossible to find today.

[bigjim5551212]

the 2.2 had an adapter plate that went from the manifold to the carb. That would not fit the Opel.