Cutlass Fan

If my car (65 Cutlass 330) sits for more than a day it takes a lot of cranking to get it started. I assume the fuel bowl is empty, will pull the top of the carb off next time before starting. It is a Rochester 4 jet and was supposedly rebuilt just before I got the car. I've read that this is a fairly common problem with this carb, but I haven't come across a good solution. Anyone here got a solution?

MDchanic

I hate to say this, but this question has now come up at least four or five times in the past 2 weeks, if my memory is correct.
I haven't said much, but, really, my answer is: Crank it a lot when it hasn't run for a while.
That's what everyone used to do in the '60s, '70s, and '80s, and nobody really thought much of it.

You can drive yourself nuts looking for a "solution" to a condition that was never really considered a problem at the time when these cars were in common use, or you can just accept it.

- Eric

joe_padavano

Unfortunately, people who are used to modern EFI motors with electric fuel pumps have forgotten the "joys" of living with a carb.

Look, the carb has a float bowl that is simply an open container of gas. If the car sits for any length of time, this fuel starts to evaporate. On older cars it goes into the atmosphere, on newer cars it goes into the charcoal canister. Either way, it is NOT in the fuel bowl any longer. Hot temps and today's ethanol-laced fuel makes this worse.

Compounding the problem are older mechanical fuel pumps where the diaphragm and check valves are likely deteriorated from the ethanol as well, reducing pumping efficiency.

One option is to live with it. A new fuel pump with ethanol-resistant materials will help fill the carb faster. A cleaned-out fuel tank with a new inlet sock that isn't clogged with rust and debris will also help. The ultimate solution is an electric fuel pump that allows you to fill the carb before starting. This obviously won't look stock, but it is the best solution for a driver.

Cutlass Fan

Thanks for the responses. I grew up with car orated cars and realize they don't start as quickly as efi. I wasn't considering modern fuels evaporating more quickly though. I'll try replacing the fuel pump.

MDchanic

I would just add that until somewhere in the 1990s (if I recall correctly), Consumer Reports had a section in every car review called "Starting and Running" in which they discussed and rated just those things, under various conditions.
At a certain point they realized that for the past several years, every car that they had tested had received perfect scores in this area, so they dropped the section.

It is very easy to get used to things that are nicer, smoother, easier, without even being aware of it, and then when we are presented with something that is the way things used to be, it seems wrong in comparison.

- Eric

hookem horns

Back in the "old days" we usually drove our carbureated cars enough to avoid this. You can also refill the bowl through the carb vent if it really bugs you but make sure to put the air cleaner back on before starting in case of a backfire. For me, I'll crank the engine for a few seconds to run the fuel pump before ever touching the gas pedal if it has sat for more than 4-5 days. Then pump the pedal once to prime the carb and set the choke (cold start procedure in owner's manual) and it usually fires right up.

BlackGold

Two comments:

First, I've driven carbureted cars all my life (only one has had fuel injection), and I never had problems with the float bowl evaporating "back in the day" the way we have problems now. I agree that evaporation -- especially with a hot engine parked on a hot day -- is the problem. But today's gasoline must be much more sensitive to this than the gas 30 years ago.

Second, carbureted cars actually start quicker than EFI cars -- provided that there is fuel in the float bowl. At least a car with it's carburetor properly adjusted does. I absolutely love how my cars start with just a touch of the key. All I need is one cylinder to fire and the car will start. With EFI it always takes an entire revolution or two of the engine before the computer even fires the first spark. I find this annoying.

MDchanic

Me too, actually.

Even more annoying is the additional delay for the key ID computer before the car allows itself to crank (in one of my cars, anyway).

- Eric

oldcutlass

I'm not fond of the fly by wire throttles.

Cutlass Fan

I realize that "back in the day" we used our carbureted cars on a more regular basis but I never remember the carbs going dry unless they sat for an extended length of time not overnight. I had my car running yesterday evening for about 5 min, this morning I still had to crank it an extended length of time. Does today's fuel evaporate that much quicker?

oldcutlass

Did you pop the air breather and operate the throttle while looking down into the carb to be sure they are going dry?

Sugar Bear

Confirm that the choke plate closes completely after sitting overnight and opening the throttle one time.

Cutlass Fan

I will check both

distributorguy

I just fixed an issue with this in my '55 Chevy truck after a couple years battling it.
1. The check valve in the fuel pump can fail, resulting in fuel flowing back down the line in the wrong direction while parked.
2. The tiniest vacuum leak in the fuel line also helps this to happen - like a compression joint that's either crushed or just vibrated a little loose.
3. A carb issue that allows fuel to leak out of the float bowl such as a leaking core plug can cause an empty fuel bowl when you come back to it.
I'd start with this list, in this order and not just blame evaporation, which will only account for the volatiles in the fuel.

joe_padavano

I agree that the check valves in the pump can and do go bad, and that certainly will cause the pump to lose prime and/or take longer to fill the carb, but the float bowl in the carb itself can't drain back out the needle and seat. The needle and seat are above the fuel level in the carb, so unless you are parked on a VERY steep hill, the fuel in the bowl would need to jump up to reach the needle and drain out. It DOES evaporate out, however, which is where the weak valves in the pump cause a problem with refilling.

distributorguy

Fuel can drain internally, to the level of the jets, and bingo - no gas. I've seen it more in Quadrajets - haven't rebuilt a 4-jet in 8 years. Actually got a rebuilt carb once (came on a truck I bought) that had a plug epoxied in the bottom of the carb, which of course still leaked.
Fill the carb with alcohol and let it sit for an hour - on the bench. Look for weeping. Not the most likely issue, but worth checking.

jaunty75

Someone explain to me why, if modern gasolines are at most 10% ethanol, this should cause the entire quantity of gasoline in the float bowl to evaporate more quickly? I can see the ethanol portion evaporating fast, but that should still leave the rest of the volume of fuel, about 90% of what was there when you last shut the engine off, still there to evaporate at the rate gasoline always did evaporate back in the day.

I use gasohol in my '67 Delta, and I never have a problem starting it a day or two after the last time I drive it. One pump of the pedal, quick touch of the key, and off we go.

If I let the car sit for a couple of weeks between starts, then, yes, I have to pump the pedal a few times and crank. I expect that. But for short times between running of the car, such as overnight or a day or two, there should not be complete evaporation of the gas in the float bowl. If you're experiencing this, you have a leak somewhere.

Ethanol fuels were introduced back in the '80s or perhaps even earlier, well before carbureted engines left the scene. If overnight evaporation of the fuel caused hard starting on a regular basis, even in new cars, which is what you would expect if the fuel really were completely evaporating overnight, this driveability problem would have been all over the news. But it didn't, and it wasn't.

BlackGold

So maybe it isn't the ethanol itself, but the whole fuel package. I'm sure they've made other changes to gas beside adding ethanol.

Regarding the comment about only the ethanol evaporating: I'm no chemist, but I don't think it works like that. The ethanol and gasoline are a mixture which behaves differently than the two components themselves.

I do know for a fact that the fuel evaporates out of the Qjet on my '87 442. If I start the engine and run it just long enough to fill the float bowl, then shut it down, when I try to start it again 10 hours later it fires right up. But if when I shut it down the engine is at operating temp, especially on a hot day, when I try to start it up 10 hours later the float bowl is empty. Obviously the fuel isn't leaking out, unless the leak is temperature sensitive.

jaunty75

Here's an interesting read. The situation is not simple, but the conclusion (see the last page of the article) is that a quantity of ethanol mixed in gasoline will evaporate faster than a similar quantity of pure ethanol left by itself. This is because the diluted ethanol molecules in the ethanol/gasoline mixture are isolated from each other and thus don't undergo the hydrogen bonding that they would in the pure liquid. But see Figure 2 in the paper. This is only true up to an ethanol concentration of about 10%, which is what gasoline today has. When the concentration of ethanol gets above 10%, the ethanol molecules are not dilute enough and thus begin to interact with each other through hydrogen bonding, thus reducing the rate of ethanol evaporation.

But no effect of ethanol on the evaporative properties of the components in gasoline was noted. As the article puts it, "ethanol does not appear to significantly affect the evaporation of specific compounds or compound groups." In other words, ethanol does not affect the evaporative properties of the components of the gasoline in which it is mixed. They determined this by comparing the fraction of the various gasoline components in the initial liquid to their fractions in the condensed evaporant.

For this last point, see Table III in the paper. It lists all the components of gasoline, of which there are more than 40, and even this isn't all of them because the first component listed is "unidentified."

http://www.tandfonline.com/doi/pdf/1....1994.10467294


The bottom line here is that it is not correct to simply say that "ethanol causes the fuel in my carburetor's float bowl to evaporate more quickly." It doesn't. The ethanol portion will evaporate more quickly than a like quantity of gasoline, yes, but that still leaves the other 90% of the fuel mixture, the gasoline component, unaffected. It should take just as long to evaporate as gasoline ever did.

MDchanic

Interesting. Thanks, Jaunty!

- Eric

jaunty75

You're welcome.

It's just always bothered me how much modern gasoline gets blamed for every problem people encounter with their fuel systems, driveability, or whatever with their old cars. I think modern gasoline gets blamed for far more problems than it actually causes. It's a convenient scapegoat.

I have owned four old Oldsmobiles in my time, a '64 Jetstar 88, '67 Delta 88, which I have now, a '73 Custom Cruiser, and a '75 Delta 88. I never had a fuel-related problem with any of these cars. I've never done anything beyond the norm in maintaining them. When I've rebuilt carbs, I just used whatever parts came in the kit I bought at the local auto parts store. When I replaced fuel lines or vacuum hoses or gaskets or any other rubber parts, I just used what the parts book at the local NAPA store told me I should use and that the parts guy took off the shelf. I never worried about whether it was "ethanol ready" or whatever, but I did assume that whatever I bought is compatible with the fuel used by modern cars.

Keep the car in good tune. Keep the seals and hoses and lines and whatever current, and you should be good to go.

distributorguy

Jaunty, 100% correct! The two things I've personally noted about modern fuel are these:
1. It is harder on natural rubber seals, which are being eliminated from most carb rebuild kits. Viton works perfectly well and is an easy substitute.
2. Modern fuel has 2 new issues. The etahnol does evaporate off, in about 2 weeks time. This is only notable in engines that require the octane - those that don't will run the same. Octane does decrease as ethanol decreases. Also, the new fuel compound, most notably from the last 5 years, is more difficult to ignite under low cylinder pressures, requiring more initial timing. We are all seeing this, in any compression level engine. As dynamic cylinder pressures rise, the effect is minimized with 1 degree of variation or less from that of the 60's fuel we all crave.

Yes, this whole issue of losing fuel in the bowl can be at least partially temperature related. Internal carb leaks are usually caused at a location of differing materials - where the aluminum casting leaks around a steel core plug. Thermal expansion. Plus there's' the issue of the car being out of tune, running hot (not enough timing) and evaporation of hot fuel in the bowl. Like I said earlier, this is likely a combination of a few things wrong.

jaunty75

This should bother you for one simple reason. Unlike most of the cars that get talked about on this site as having problems with alcohol fuels, which are cars that were built before the gasohol era, your car was built well after we were into the era of oxygenated fuels. By the late 1980s, oxygenates like methyl tertbutyl ether (MTBE), ethyl tertbutyl ether (ETBE), and ethanol were being mixed with gasoline and in use all over the country. So your car was designed and built to run on these fuels. To argue that the problems your car is having are being caused by ethanol in the fuel is to argue that the problems your car is having are being caused by the very fuel it was designed to run on. This just makes no sense.

Cutlass Fan

Thanks for all the responses. I've discovered if I pump the accelerator a couple of times just as it tries to start it will start quicker. This is after it has sat only over night, so I'm thinking that even though the choke closes initially maybe it partially opens when cranking. I haven't had time to check as we just completed a 400 mi. trip in the Cutlass over the weekend. There were NO problems! And even though the timing needs to be advanced (no pinging even on 81 octane) it still got about 16 US mpg at 65 to 75 mph.

distributorguy

So the float bowl is not empty in the morning? Yes you need to pump the throttle and squirt a little fuel to get the car started.

Cutlass Fan

I floor the pedal once to set the choke then hold the pedal part way down when cranking. If I just do this it will fire but not start and then it takes a lot of cranking before it starts. That is what made me suspect a dry bowl. If I pump the gas pedal just as it fires it will start. Sure starts good hot though.

distributorguy

Holding the throttle open while staring is what you do with a flooded engine - to lean out your fuel mixture. Pump the throttle once or twice as need to set the choke, then get your foot off it!!! Never owned a carbureted car before???

jaunty75

This is not surprising. You are flooding the engine by holding the pedal part way down after setting the choke. You should read your car's owner's manual.

To start a cold engine, press the pedal to the floor and release. This sets the choke. KEEPING YOUR FOOT OFF THE PEDAL, crank the engine.

To start a hot engine, press the pedal half-way and hold while cranking.

BlackGold

Ah, but I did not argue that my problems are caused by ethanol. Read my post. All I said was that I have proved to myself that the emptying of my float bowl is much worse with a hot engine, non-existent with a cold engine. Whether this is due to ethanol or any other substance in today's gasoline is a separate issue. I agree with you.

Cutlass Fan

I guess I'm getting forgetful, but I'm sure that on some of the many carbureted vehicles I've owned over the years recommend flooring to set the choke the part throttle to start. I now see that the owners manual says to set the choke then foot off. Guess I shouldn't trust my memory and read the instructions. And yes I know al about holding the throttle WIDE open to clear a flood.

Leadfoot

I experienced the same issues as so many others report with hard starting/long cranking after the car sits for a while. For me, "a while" was as little as 2 days. It almost always required cranking the engine for 10-15 seconds, two or three times before the engine would fire.

Amongst all of the other work I've done under the hood over the past 10-12 months, I replaced the fuel pump, the hard fuel line to the (2MV) carb, and the (2) rubber hoses from the fuel pump to the tank hard lines. I also replaced the partly crushed fuel filter.

After the car had sat without running for 9 months while I was doing other stuff, it started up after cranking about 6-7 seconds, first try. I was pleasantly amazed, considering that the fuel system forward of the hard lines to the fuel pump was completely dry (although I didn't check the float bowl). After sitting for 4 days, the engine started after less than 2 seconds cranking, just as I would expect a normal engine to do. Note that I did not touch the carburetor or anything else in the fuel system while working under the hood during the past year.

My only conclusion is that the check valve in the old fuel pump was shot, and all or most of the fuel was draining back to the tank. This should not have caused the float bowl to empty, but gravity could have created a fair bit of negative pressure at the float bowl needle... and I have no other explanation.

The Rochester 2MV does have its inlet in the side of the float bowl, which I know is different from the Qjet... but it's just not reasonable to expect the fuel stored in either carb to simply evaporate and dry out in just a few days or even weeks. I'm (at least temporarily) convinced that the fuel pump is at the heart of most of these problems.

MDchanic

Some of the hoses and tubing you replaced could have had pinholes, as well.

Anyone who's ever cranked the engine with the fuel pump pumping into a bucket has seen that it only takes a few revolutions, if that, to fill an empty float bowl.
If constant cranking is required, it's likely because of a need to overcome an unprimed pump.

- Eric

66-3X2 442

Anybody who thinks that ethanol fuel doesnt evaporate faster than regular fuel is only fooling themselves. To think the ethanol evaporates and leaves the regular fuel there is nonsense. Think about what guys use to do when moisture got into the fuel. They added alcohol to mix with the fuel so it would help burn the moisture. One thing that helps with hard cranking after sitting is to put a restrictor in the return line if equipped with one. As a matter of fact,66 442s came with a restrictor in the return line. I found some NOS restrictors on eBay and bought all of them. I have one in my car and it seems to help with the drain back problem.

Leadfoot

Absolutely true. Even though I had no detectable fuel leaks anywhere, the rubber hoses and the carb line were not in good condition and could have been allowing air into the system under the 30" w.g. or so of negative pressure created with the fuel pump not operating.

I'm still at a loss to explain why the engine doesn't seem to want to fire and run on just the fuel in the float bowl. Although the bowl is small, it seems like plenty of fuel to start and run the engine for a few seconds... I need to study the carburetor design a lot more...

distributorguy

The most likely answer is that your choke is hanging up, along with fuel line issues. I've seen all of the above scenarios, except for ethanol fuel being the cause. That's as big an excuse as "vapor lock," which is usually just a poorly tuned car - running too rich and flooding on hot start-up. Basic tuning, quality fuel lines with no leaks, and a proper starting procedure for the car are all equally important.

There's nothing to study about the carb design. The car WILL run on a full float bowl. A partially full bowl will go empty when you hit the accelerator pump a few times and then it won't start.