Will not start

[spolij]

66 Deville convertible, 429 engine Rochester carburetor.
The car was running fine last week. Three pushes on the gas pedal started right up. Went to start it yesterday morning it would not start unless the choke was opened manually when the engine is cold. If the choke is closed the engine will start using starting fluid. Once the engine runs and warms up enough, it starts every time without pumping the gas.
Any thoughts?

[James Landi]

Perhaps your automatic choke is set too tight--or closed--- we're experiencing very cold weather, so your automatic choke may not be permitting the butterfly to open, so it's choking off the air and providing too much gas.   If my "theory" is correct, wait for the temperatures to moderate, and find out if the car starts as usual.  Obviously, my theory is based on your car being in an unheated garage and that you're located in a region that is experiencing very cold weather.  Hope this helps,  James

[savemy67]

Hello John,

If everything was perfect, you should only need to pump the gas pedal one time to set the choke and fast idle cam. Given that you indicate your normal starting routine is to pump the gas pedal three times, I would hazard a guess and say that your carburetor needs to be adjusted or rebuilt, with focus on the choke assembly.

If the choke does not open after the engine has run a minute or so, the thermostatic spring in the choke housing could have failed and or there is a vacuum leak to the little piston in the choke housing.

I remember using starter fluid in my Rochester 2GC when I lived in Minnesota 45 year ago, and the temperature was -15 F.  The 4GC is essentially two 2GCs back to back.  Almost any engine will start using starter fluid, but the carburetor should be in good condition with the choke properly adjusted.

Three pumps of the gas pedal dumps a lot of fuel into the manifold.  On a cold day, the fuel may condense into a puddle before it atomizes with air to get the engine running.  Is it substantially colder this week than last week where you live?

Has your carburetor been rebuilt or adjusted properly?  You identified it as a Rochester, so it should be a 4GC.  Is it original to the car?  Adjusting it yourself will be less expensive than taking it to a shop (which probably would not know how to work on a carburetor unless its a specialty shop).  Have you considered rebuilding it yourself?  You could do so for under $100, but if you don't feel like you can tackle the job, have the carb professionally rebuilt ($300 - $400???).

When warmer weather returns, the car may start OK, but the problem, whatever it is, is likely to manifest itself again, so you may want to take care of it now.

Repectfully submitted,

Christopher Winter

[Jon S]

 Carbureted cars were designed to start in all temperatures so I don’t think the choke is the problem.  It should close fully on a cold morning. If your carburetor has recently been rebuilt and you know the accelerator pump is good then it might be flooding the engine with three pumps if opening the choke enables you to start the cold engine    Your carburetor has an unloader capability. Next time try one pump and see if it starts. Otherwise activate the unloader by holding the accelerator pedal to the floor for a minute and then releasing it and then turning the key with your foot off the pedal. 

[Daryl Chesterman]

Try this: manually open the choke butterfly (before trying to start the engine) and actuate the accelerator linkage while looking down into the carburetor.  There should be two strong streams of gas going into the throat of the carburetor as the linkage is quickly operated through its range (simulating pumping the accelerator pedal).  If this is good, try starting it with just that one pump of the accelerator.  If it starts, does the choke butterfly open up approximately 1/4"?  If it does and the engine remains running, you have just found the new way to start your engine, and as Christopher Winter says, is the proper way to prime the carburetor to start the engine.  However, if the choke butterfly does not open up that little bit on the initial start, and the engine runs rich, then the choke system will have to be analyzed to see if it is properly adjusted.
Does the choke open completely when the engine is warm?  If not the choke cover needs to be adjusted so that it is open when the engine is completely warmed up.  Then the test is does the choke close completely when the engine is cold and the throttle is actuated.  If on the initial start, the engine runs rich and the choke butterfly is not opening at all, pull off the choke cover and see if the inside of the choke housing is full of carbon.
If full of carbon, that would indicate that the tube that goes to the choke housing is burned through, allowing exhaust gas to enter the choke housing.  There should be no carbon inside the choke housing.  If carbon is present, this would probably plug the vacuum path that enables the initial opening of the choke butterfly and helps to pull open the butterfly as the engine warms up, and the thermostatic spring uncoils.

After a car has been sitting a few days, the fuel may evaporate from the float bowl, and then the initial pump of the accelerator will not provide any fuel for the engine to start, which will require cranking the engine a little so that the fuel pump can put fuel in the float bowl.  I crank a little and while cranking I pump the accelerator once and if it doesn't start( while continuing to crank) I wait a few seconds and pump again.  Usually, it will start on the 2nd or 3rd try--no more than 5-10 seconds.  If one has added an electric fuel pump, this negates much cranking after a car has been sitting.  The other option to negate having to crank the engine so long is to do as another poster has said, and that is to inject fuel into the carburetor bowl by putting fuel into the vent tube with a syringe.

Daryl Chesterman

[Scot Minesinger]

Best not use starting fluid.  Three pumps may be flooding it.  One pump is all it should need. 

[chevy350]

I working on '77 K5 from a friend with an original just rebuilted Rochester(divorced choke),When the engine is really cold and it start I have a lot of black smoke(unburned fuel) and the choke butterfly is totally closed,when the engine start to warm up the butterfly open.
From the carb thermostat heather I have just a ling,I need to change the carb thermostat heather? I think it can be adjusted.


I apologize if I hijack the post but the symptom are similar.

Greeting from Italy and have a nive W.E.!

[cadillacmike68]

Carbureted cars were designed to start in all temperatures so I don’t think the choke is the problem.  It should close fully on a cold morning. If your carburetor has recently been rebuilt and you know the accelerator pump is good then it might be flooding the engine with three pumps if opening the choke enables you to start the cold engine    Your carburetor has an unloader capability. Next time try one pump and see if it starts. Otherwise activate the unloader by holding the accelerator pedal to the floor for a minute and then releasing it and then turning the key with your foot off the pedal.

Yes, one press should completely close the choke on a stone cold engine (engine at ambient temp), BUT venturi pressure / vacuum should open it to allow air to come through and if it is sticking, then it will flood, the remedy being holding the pedal to the floor which forces the choke to open up.

Periodic application of generous amounts of Gumout or a similar product while idling helps to minimize these things sticking too much. I also use Only toptier gas with all my cars, premium for the 68 because of the compression ratio

And yes, it is back to being Florida cold down here - below 60.    Still top down weather though. 

[spolij]

Tried to start the car today it was about 30° out. I had originally set choke to be open about an eighth of an inch on a cold engine. That's the way it was today I gave one push on the accelerator, cranked it but it wouldn't start. I did it again, one push on the accelerator cranked it over wouldn't start. I set the choke to be wide open, and space it fired right up. After it was warmed up I hit the gas brought it down to normal idle and choke was wide open.
Once the car started it'll start up with just cranking the engine no gas, all day long.
The carburetor had been checked out by a guy who's shop was in a pole barn on his property there were a lot of carburetors there, he seemed to know what he was doing there was a problem with the accelerator pump don't remember exactly what. He said the carburetor had been rebuilt recently. But like I said last week it started on its own with no problem and it was just as cold as was this week so I don't know what is going on.
All check out a few of the suggestions again tomorrow and if I can't figure it out have to bring it to my local mechanic thanks all.
John

[Jon S]

 Part of what you’re saying makes no sense whatsoever.  If you started the car with the choke wide-open you completely disengaged the fast Idle cam so saying after it warmed up you kicked it down to normal idle. The idle is only increased by a closed or partly closed choke activating the screw setting on the fast idle cam. With a fully open choke, the screw does not touch the fast idle cam. It sounds like your carburetor linkage is screwed up

[spolij]

Jon  You are correct I manually set the choke to wide open position started the car and then because the engine was actually still cold, I put it onto the fast idle setting. (That's the part I left out LOL) sorry about that.

[Jon S]

Ah, OK

[spolij]

I been looking at remanufactured carburetors online. Almost all the vendors are pushing Edelbrock while mine is Rochester. Most of them, with an electronic choke I think I want to stay away from that. The problem is looking at the pictures all the linkages seem to be different from what I have most of them don't have the idle bypass screw in the back of the Rochester carb.

[cadillacmike68]

I still think something is sticking. I would get a couple cans of Gumout, get it warmed up, hold the throttle partly open with one hand and spray the hell out of all the linkages and the carb throats. Do it in spurts until it almost stalls and use the throttle to keep it running. Use at least one full can. The engine heat will evaporate any external overspray.

I used to do this up in MA when it was real cold - not Florida cold - say 10-20 out. No carb issues. I won't get into other issues.  I still do it now, because the gas can varnish up so bad so quickly.

[spolij]

Daryl everything checks out like you said.

[Daryl Chesterman]

John, if you are able to start it with only one pump of the accelerator and a wide open choke, have you tried to start it by just barely opening the throttle, to set the choke and then trying to start it, thus eliminating a full initial shot of gas?  If it starts then, there is definitely something in the carburetor that is allowing it to start rich, and would indicate the need for a carburetor overhaul.  Before doing a carburetor overhaul, be sure that all of the ignition checks out to specifications--dwell, timing, etc.  I really don't think that there is a problem with the ignition--it seems to be a fuel problem--but it is worth checking out first.

I had the Carter carburetor off of my 59 Deville worked on by Daytona Parts Co.(highly recommended by several on this board)and they did a very good job.  They also did an Autolite 2100 for me, and they were very helpful when I had to call them on a follow-up phone call.  It might be worth a call to them and see what they say, since classic car carburetors are their business.  The Carter overhaul was not cheap, at $300+, but was basically plug and play, with a minor idle air adjustment and hot idle speed adjustment.

Daryl Chesterman

[cadillacmike68]

Let me put on my IBM THINKpad hat. (I exclusively use ThinkPads).

It was running fine a week before the first post and then started acting up.

I don't think the carb just up and broke itself. Something, most likely the choke plate or its associated linkages and springs, started sticking.

Have you taken off the air cleaner while it's stone cold and used the Only throttle linkage to set the choke and observe? Is it like 95-100% closed?  Can you GENTLY press the bottom of the plate to open it with NO EFFORT?

If it does not set with the throttle linkage or if you cannot open it as noted above then something is sticking.

I would by a whole case of Gumout before taking it off and sending for a $300 rebuild.

[James Landi]

John,

Several of us who are shade tree mechanics have recommended Gum Out spray, and I would add some WD 40  spray as a "chaser" as metal to metal contacting parts tend to "hang up" once the Gum Out does the work of cleaning.  The automatic chokes on the newer models also had "vacuum breaks" that where intended to withdrawn and permit the choke plate and throttle to thermally adjust.  If you have a small vacuum actuator on your choke related assembly, you'll see the 1/8 hose that is intended to move it.  Check for leaks by simply sucking on the hose and see if the vacuum break is working.    Hope this helps,  James

[spolij]

Darrell   there are two streams of fuel going into the carburetor.
Mike   I didn't have any gum out the choke linkage felt good but I sprayed it with WD-40 anyway and it did loosen up quite a bit. Sure -  rub it in Florida below 60 I'll have you know it got up to 30 in Ohio yesterday! A few months ago I took the choke apart and cleaned it and then set the choke in the closed position with about an eighth of an inch space.
James   I don't see a vacuum actuator is choke. The only vacuum units i have are to raise the idle for the air conditioning and the vacuum advance.

I started checking the linkage to the carburetor according to the shop manual i found the secondary lockout lever didn't seem to be adjusted properly so I reset it. It did start up right away with one press of the fuel pedal. A few hours later after it cooled off I tried to start it and it was the same problem. This morning I went out tried it and again the same problem. It did start but I had a feather the  gas pedal. It did go right to high idle and kept running.
I'm going to go through the linkage adjustments again today and double check everything. But then I'm done.
Darrell  I'll check out Daytona parts but in researching carburetors on the Internet the big difference is the core refund I don't know if it's worth sending the core or just buying a carburetor.
Most of the sites I checked out are pushing Edelbrock carburetors. Anybody have a view on whether it's worth going with that or stay with the Rochester carburetor. My biggest worry with the Edelbrock is according to the pictures there are so many different types of linkage setups and it's very confusing I guess if I call the vendor and get their advice I should be okay. But what does anybody think about the Edelbrock carburetor?

[spolij]

Today I am going to recheck linkage adjustments, timing, idle setting and adjust the needle valves. Needle valves are in the base plate and I think there in there pretty sloppy they do wobble. I wonder if you set them up and then after running the engine a while, being loose in the base plate they moved and threw the adjustment off. I had to replace the needle valves a while ago and they still wobble.