Weber Issue: No Start After Sitting

[2ndGenGuy]

So, I've been having a problem recently where my car won't start after it sits for a few days. If I drive it every day, there's no problem. But probably after about 5 days, it seems like maybe the float bowl dries up or something, because the car won't get any fuel. If I spray a bit of starting fluid in, she'll fire up, stumble for a couple seconds and then run just fine and I'll have no more starting issues after that.

So could there be something draining the float bowl in the carb? Or maybe my top hat is just not tight enough? Any suggestions? I used to be able to let the car sit for a month, and then it would fire right up.

This is a Weber carb, BTW. No stock emissions controls, or vacuum line mess.

[carotman]

is there a way to check the float level on the weber?

I would start with that.

[Rendon LX-i]

THeres has to be a slow leak some place

[w261w261]

Sorry, my carb experience is of the lawn mower variety...but does the float bowl attach with a long bolt up through the bottom? If so, it can leak slowly if the bolt is loose or the small gasket is compromised. You didn't mention a gas smell?

How long do you crank it before giving up when it won't start?

[2ndGenGuy]

is there a way to check the float level on the weber?

I would start with that.

Yeah, I can take the top hat off. Now sight glass like the stock carbs... But I don't seem to have any drivabilitiy problems. I guess if the float level is sticking shut after the bowl dries out it would keep it from filling up. Maybe the jolt of the engine starting with the starting fluid knocks it down or something... I'll give it a check tonight, easy to do and can't hurt.

THeres has to be a slow leak some place

That's what I'm wondering. Maybe accelerator pump, or leaky power valve?

Sorry, my carb experience is of the lawn mower variety...but does the float bowl attach with a long bolt up through the bottom? If so, it can leak slowly if the bolt is loose or the small gasket is compromised. You didn't mention a gas smell?

How long do you crank it before giving up when it won't start?

I've cranked until the battery is almost dead. As soon as I give it a tiny, tiny squirt of starting fluid, all is good. I definitely can't smell any gas. But yeah, the power valve is in the bottom of the bowl, so maybe I'll put a new o-ring on that and see if that helps.

[88Accord-DX]

I have the same thing happen to me when I let the car sit (weber 32/36) in the garage for weeks at a time. The float bowl seems to evaporate the gasoline in it & takes a few 30 seconds for the fuel pump to prime it up.

[carotman]

If the fuel dries up in the bowl, it will not be refilled until the pump sends in fuel.

The fuel pump is sending fuel each time the relay is trigged. The relay is trigged by the coil.

This is why it takes a few cranks to fire it up. I have that same problem on my hatch. I found out that if I hardwire the fuel pump before starting the car, the problem goes away.

You could always try to do that.

[Dr_Snooz]

The car is obviously telling you that you need to drive it more.

[2ndGenGuy]

The car is obviously telling you that you need to drive it more.

+1


I see what you mean Carotman, but for some reason it will not start at all. It's like the fuel pump won't fire until the car is actually running... I would think a few cranks and it would be full.

[79cord]

What about that relay system that is supposed to run the fuel pump for a few seconds after you first turn the key to prime/fill the carburetor?

[carotman]

+1


I see what you mean Carotman, but for some reason it will not start at all. It's like the fuel pump won't fire until the car is actually running... I would think a few cranks and it would be full.

It takes quite a few cranks to fill up the fuel hose that is also empty from the bowl drying out and to fill the bowl past the jet.

You usually don't notice this when you have an already full bowl.

[lostforawhile]

What about that relay system that is supposed to run the fuel pump for a few seconds after you first turn the key to prime/fill the carburetor?

yea, but it's designed to prime a sealed fuel system where the gas isn't supposed to all evaporate out of the bowl. on an unsealed system it can evaporate quick. I added a push button switch that bypasses the safety relay when pushed, you just hold it until the fuel bowl fills. It won't overfill, once it's full the float will cut it off like normal.

[2oodoor]

if the bowl is dried up, that would not be the fuel pump! Where is you auxilary fuel filter located under the hood? higher than the bowl or lower.. think on that one.. lol
If the choke is working it will pull fuel up from the bowl when you cold crank.
Could be power valve, throttle not closed, accel pump system (is this the dual one you have?)
See if your oil is getting a lot of gas in it too if this happens a lot you are contaminating oil.

[Hazwan]

What about that relay system that is supposed to run the fuel pump for a few seconds after you first turn the key to prime/fill the carburetor?

Do they come with that stock? I remember reading that somewhere. I'm having similar problem except mine is stock carb. It wont fire up after sitting for more than a week unless I spray some starting fluid into it. Never bothered me that much since I rarely left her for more than 3 days :p

[lostforawhile]

if the bowl is dried up, that would not be the fuel pump! Where is you auxilary fuel filter located under the hood? higher than the bowl or lower.. think on that one.. lol
If the choke is working it will pull fuel up from the bowl when you cold crank.
Could be power valve, throttle not closed, accel pump system (is this the dual one you have?)
See if your oil is getting a lot of gas in it too if this happens a lot you are contaminating oil.

the webers are vented all the time to the atmosphere, the bowl is vented, if it wasn't the jets couldn't pull fuel out of the bowl. if you let it sit the gas is going to evaporate out the vent.

[2ndGenGuy]

Well, I don't think it will evaporate that quickly even if it's vented. This is a new issue. I've let it sit for longer without any problems. I've had this carb for 5 or 6 years, bought it brand new, it's probably time for a little bit of an on-car rebuild.

I do need to check the oil for gas though. If it's draining in the carb internally, that's going into the intake manifold and down into the cylinders, and probably eventually past the rings. I didn't have any time to even look at it last night, so I'll have to check it out probably this weekend. So much to do damnit!

[tomatofiasco]

the standard carb is vented too, with two big holes bored in the top plate over the float chamber. i know this from when i turned one upside down and got wet. my carb is really crusty and not at all new but the car starts up, whatever the weather, even if its been a week in the sun, with about 2-3 cranks on the second choke detent. i have heard my fuel pump run when i turn the key to ON, so i guess the chamber evaporates a little bit of fuel and needs topping up.

just puzzling it out, none of the jets can drain from gravity alone. the accel pump, if its at all like the keihin carb, is at the bottom corner and often leaks, but this is really really obvious because there will be a clean area below it, on the heat shield or whatever, where the petrol has dripped. it also smells like a Caltex HQ whenever you return after having parked.

on the standard carb theres an idle jet, right at the bottom lip of the carb body below all the butterflies. directly behind it, protruding from the carb is the idle mixture screw, and directly above that is the shutoff solenoid. this is spring-loaded shut and magnet retracted. i assume your weber has one similar, and if it didn't return properly it might cause overrun backfiring and, depending on the plumbing, allow fuel to bleed out when the engine was off. fine channels might also have a capillary effect.

its interesting that others are reporting a similar period before the car wont start, it suggests to me a uniform-ish rate of leakage, so perhaps its a similar or identical problem in most cases, metering out fuel at a similar rate into stationary engines of about the same capacity...

or, not.

[lostforawhile]

the standard carb is vented too, with two big holes bored in the top plate over the float chamber. i know this from when i turned one upside down and got wet. my carb is really crusty and not at all new but the car starts up, whatever the weather, even if its been a week in the sun, with about 2-3 cranks on the second choke detent. i have heard my fuel pump run when i turn the key to ON, so i guess the chamber evaporates a little bit of fuel and needs topping up.

just puzzling it out, none of the jets can drain from gravity alone. the accel pump, if its at all like the keihin carb, is at the bottom corner and often leaks, but this is really really obvious because there will be a clean area below it, on the heat shield or whatever, where the petrol has dripped. it also smells like a Caltex HQ whenever you return after having parked.

on the standard carb theres an idle jet, right at the bottom lip of the carb body below all the butterflies. directly behind it, protruding from the carb is the idle mixture screw, and directly above that is the shutoff solenoid. this is spring-loaded shut and magnet retracted. i assume your weber has one similar, and if it didn't return properly it might cause overrun backfiring and, depending on the plumbing, allow fuel to bleed out when the engine was off. fine channels might also have a capillary effect.

its interesting that others are reporting a similar period before the car wont start, it suggests to me a uniform-ish rate of leakage, so perhaps its a similar or identical problem in most cases, metering out fuel at a similar rate into stationary engines of about the same capacity...

or, not.

the standard keihin is not vented to atmosphere, that's the job of the big valve stuck to the side of the carb, when the engine shuts off that valve closes the float chambers to atmosphere, and all vapors go to the canister. on the three g it has a backup bowl vent built right into the valve in case the main vent fails. when the engine is running, there's a negative pressure on the float bowls due to air flowing into them, this prevents fuel vapors from escaping. the jet passages are also closed off by the fuel solonoid valves on the carb. thats the valve with the single wire on the side of the carb, the cvcc carb has two of them. There are a lot of systems on these cars to prevent fuel evaporation to atmosphere.