VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Die on Idle, Smoke from Carberator

Just when I thought she was running great, I've run into a new issue.

Just installed a rebuilt distributor on my '41, timed it, and had her running perfect - steady idle and smooth acceleration until I shut her down. Now, all of the sudden, she wants to start up immediately without even choking, but she runs for less than a minute before coughing and dying. When she dies, I notice smoke drifting out of the air cleaner.

Wondering if this isn't a sign of a plugged fuel filter or something else. Has a new inline filter but the part of the line that runs from the fuel pump to the carb is original, which means it could still have had some gunk in it. But that's just a guess.

Wondering if anyone else has experienced this and what the problem/solution is. Never seen smoke from the carb before.

Actually, now that I think about it, the "smoke" may have been caused by my using parts cleaner on the air filter element. It may have left a residue that was evaporating off.

Removed the air cleaner, checked the fuel filter, no problems there. Not sure why, after putting in the new distributor and timing it, she would idle smoothly for however long I wanted for several days running. I haven't done anything else to her except add gas to the tank, but now she'll start immediately and idle smoothly for about a minute and then stutter and die. When I start her back up, she'll idle for only a few seconds and then die while kicking exhaust or something out of the carb. It kicks out hard enough it actually pulls a vacuum and causes my windshield wipers to move.

I'm thinking a fuel problem or maybe something with the new distributor but, really, I have no clue at this point.

Any ideas out there?

The symptoms are consistent with a fuel problem.

Hi BJ,
I wonder if you could be pulling something from the tank against the fuel line entrance? Perhaps as it runs it pulls the interference/debris and blocks the line causing the car to be fuel starved and die. Then when the car stops, the debris floats back into the tank?

I had this happen to me and it left me stranded. I disconnected the line at the pump and blew compressed air back into the tank and was able to get it home. Ultimately, I replaced the tank as it was full of scale. Try disconnecting all your fuel lines and blow them out with compressed air and see if it runs any better. Would be good if you could also drain the tank and see what comes out.

just a thought.. :)

--John

It's a brand new tank, new fuel lines, new fuel pump and new carb so there shouldn't be anything to plug anything up.

However, now I'm wondering if it's the heat riser. Went out a while ago and looked at it. It seemed suck in the closed position (pushing the exhaust down rather than up around the intake manifold) and it's very stiff to turn by hand. Makes me think it got stuck in that position and now isn't really working at all.

According to the shop manual, if the riser is stuck in either position it can cause all sorts of problems. So, I'm going to check tomorrow after making sure the riser is open before startup and then checking to see what it does as the engine heats up (should close, and then open again once the engine cools - we'll see).

I would bet it IS NOT the distributor or heat riser.

Really crazy question. What fuel cap are you using? It almost sounds like the cap is not venting correctly to allow air into the tank as fuel is used.

Here is a simple test. Start the car an let it run until it stalls.. Listen while you open the fuel cap.

It would not surprise me if you hear air rushing into the tank and even the sheet metal in the tank flexing.

To support what Rusty_37_Master said, here's some info that I discovered: Inadvertant Test of Plugged Vent in Gas Cap

Hope this helps, Dean

Well, you're right about the heat riser. Made sure it was open when I started her and it didn't move (didn't run long enough to heat the engine up). And like I said, this is a rebuilt distributor from Chevs of the 40s and the engine ran great right after installing it.

I have a vented gas cap and the valve in it seems to work correctly - can hear it click when you suck in or blow on the inside vent body. And when the engine died again, I didn't hear any air moving in. Even started it without the cap on and got the same result.

Basically, the first time I start it for the day, it will start right up. But then after idling for a little while, it stutters and dies. It's hard starting after that and will die almost immediately. Go out the next day and get the exact same results - fast, smooth start, stutter and die, then hard start and immediate die.

So, if the cap is good and the filter is clean, now I have to consider if the new fuel pump isn't doing its job. I suppose it's possible I got one with a short life span - only has about an hour or two on it.

Or, makes me wonder about flooding, but I don't smell any gas.

After it starts and runs and then dies check to see if there is "spark" at the spark plugs

Then if there is spark dump about a two ounces of gas into the throad of the carbuetor and see if it starts..

Yep, getting spark. Put some gas down the carb twice but didn't have any effect. Still hard to start and then when she does, she dies. Even tried shooting starting fluid into the car while it was stuttering - just killed it faster.

Also checked fuel flow by disconnecting the line to the carb and running it into a coffee can and watching it while my son cranked the engine. Pump seems to be working fine.

I hate these head-scratchers.

The fact that the windshield wipers move and smoke comes back through the carburetor when it dies suggest that you may have a sticking intake valve or valves. You could try pulling the valve cover before startup and pre-lubing the valve stems with MMO or WD40.

Mark

Thanks, Mark, I'll give that a try today. I have the valve cover off and can see it's getting plenty of oil on the rockers.

When I replaced a broken rocker arm, I sprayed down the valve stems with PB Blaster to clean any gunk that may have caused them to stick earlier and cause the rocker arm break. Then, after replacing the distributor, she started and idled fine for a few days. Makes me wonder why the valves would start sticking now (using a cleaner instead of lubricant?). Anyway, I'll give it a shot and see if anything improves.

You said extra fuel and starter fluid killed quicker and then next day fires easy indicates excess fuel to me. That may not be the only problem considering the wipers react to the shut down.
Tony

Excess fuel was something I considered yesterday. Would make sense, if it evaporates after sitting for a while. That could be a carburetor float problem. Though it's a brand new carburetor, maybe something got through and the float is sticking (don't have any gas smell from it, though). The smoke/exhaust through the carb made me consider that an intake valve wasn't closing completely.

She does seem to burn a little oil, especially when she's stuttering. I've never had the head off to check the valves, though I'm thinking I'm getting closer and closer to having to do that. For near-future reference, how easy is it to take the head off while the engine is still in the car. I don't have any sort of engine hoist and I doubt my deer hoist is strong/reliable enough to hold an engine. I'm imagining deposits on the valves keeping them from closing properly and possibly sticking.

Along that same line, can the pistons be removed from under the engine while still in the car in case it needs new rings?

I'll try the WD-40 thing today and "endeavor to persevere."

I would do a compression test if you have not done so already. How does it run other than at idle? With excess fuel you should be getting black smoke out the exhaust and the tailpipe would have tell tale signs of soot.

Hey BJ, I had my carb rebuilt and later found that my original float had a hairline crack in it causing the car to flood. It is an easy procedure to test. Take your float out and shake it to see if fuel inside. If so, submerge in hot water and the bubbles will show the leak. Drill out the small soldered hole on top near the bracket and shake out. Then solder the crack and the small hole shut. Solved my flooding issue!

hope that helps! :)

--John

When it dies, does it seem to kick back as in out of time.

I think like Gene and Chipper that it sounds like a fuel problem but it could be timing too Of course, it hard to figure that if it runs just fine before quiting.

I have messed around with 41s like forever but never run into a problem such as you describe.

What does the manuel say about such a problem, if anything.

I hope you get it fixed. We 41ers don't abide our rides on no stinkin' hook. Just saying.

Best,

Charlie

Think I finally found the problem using the Encyclopedia Brown method (if anyone remembers who he was, you're as old as me if not older). Basically, the engine needs fuel, air and spark. I know it was getting the first two so I reasoned it had to be something electrical.

Rechecked the timing because I did have a 1964 Plymouth that would throw itself out of time upon acceleration (long story on how I fixed that "impossible" scenario, as described by a mechanic, for free). Anyway, the timing was still dead on. However, I noticed that when I turned the distributor by hand to check for a spark on the #1 cylinder, I was getting only an occasional weak spark at the contacts and no spark at all at the plug. I had previously been seeing a strong spark at the contacts.

Broke out the multimeter and checked the ignition coil, which is only about a year old. Getting 6.2 volts on one side and about 1.7 on the other side with the key on (pretty sure they should be the same, though I can't find any confirmation). Checked the ohms with the key off. Between the primary windings should be 1.4 - 1.8. Mine is showing 2+. At the secondary windings it's showing about 15,000 (should be 8,000 to 12,000). And, to top it all off, noticed that the coil felt unnaturally warm from just sitting there with the key on.

All of this may explain why the car starts easily when cold but then dies less than a minute later (after the coil heats up).

So, guess I'll be ordering a new ignition coil, unless someone shouts, "Stop! You're wrong!"

And thanks for all the suggestions! This was an annoying problem with no clear cause/solution, especially since, as I said, the coil is only a year old and I had no reason to suspect it.

If the points are open you should get the same voltage at both positive and negative posts. If the points are closed the negative post will have much lower voltage. You can also check the resistance across the points. When closed they should be nearly zero resistance.

I have had coil heating problems on several occasions. Low speeds and higher loads cause the coil to heat more. I have had to pour water on the coil to cool it and get the internal coils to shrink enough so they don't short out.

As chipper said points open same volts both sides or points closed low to near none on the points side (depending on point and distributor ground resistance). Also with points closed (current flowing) the coil will heat up but not with points open (no current flowing).

The resistance readings are a bit high but not excessive, is there a reading from any terminal and the tin case??? There should be different reading between high volts out and each low voltage terminal. The lower resistance should be points connector though there are 2 opposing theories on this.

Tony

Just to be sure (even though I've already ordered a new coil) I went out and checked it again.

With the points open, I get about 6.2 volts on both sides. Closed, 6.2 on the key side and less than 1 on the points side. So that checks out.

However, on the ohms I'm now getting 0 between the left/right terminals and 8.98K between either terminal and the center. No reading at all from either terminal to the side of the coil.

I reconnected everything and tested the #1 plug again, turning the distributor back and forth to repeatedly open and close the points. I'm getting spark now but randomly. It may spark two, three, four times in a row but then fail to spark the next one or two times. Yesterday, when the coil was warm to the touch, I wasn't getting any spark.

So it looks like it's the primary coil windings that are bad, with a 0 ohm reading (yesterday it read above 2, but then it was warm).

As a follow-up to this, I think I was wrong about the coil. Got the new one and tested it, comparing it to the other one out of the car. Both seem to be fine.

However, as I was putting in a new exhaust, I got to wondering about the condenser in the new/rebuilt distributor. Remember, she purred like a kitten when I first put in the new distributor. It wasn't until a few days later that she slowly started running a little rougher each day and getting harder to start. And even with the new coil, I still get only intermittent spark when I turn the distributor by hand. Will spark good the first couple of times but then go to an intermittent weak spark or no spark at all.

Looked up online and found a site describing how to do an ohm test on a condenser. Used both my digital and analog ohm meters and both are telling me that the condenser is bad. The site also mentions that newer condensers can often fail after only a few hours, be bad right out of the box, or last for 20,000 miles. So, I'm guessing that the new condenser in my rebuilt distributor worked for a few hours and then died.

Ordered two of them from the FS and will report back once I have one of them in. Figure I'd better have another as a backup, as the writer of the site suggested.

The meter tests on condensers are pretty vague. Due to their nature of storing electricity the readings vary as you test. Even specialized testers for condensers/capacitors have quite a range of pass/fail tolerance.

These can degrade with age regardless of usage so one of those cases where new/unused/low mileage doesn't necessarily mean good, so can have many of us scratching our heads.

As you are doing, the best "test" is just to grab a couple new ones. Most auto parts stores carry them as well as they were used in many makes and models for decades.