Who Can Diagnose THIS Total Mystery? Win A Prize?

[H. L. Chauvin]

1. With follow up #3, i.e., no heat experienced with starter/ground test in message 158 appears to indicate no reason to cut gas line if the gas line does not conduct current & get hot when the starter turns.


2. In your first message, there was something noted that "may" be a concern: "We drained the tank, saw it had been coated ... " No telling what kind of coating.


3. Some used a witches brew of thined out "Permatex No. 2" gasket sealant, & who knows what else. Even though a dreaded thought, this unknown sealant could have endured regular gas fo years; but with ethanol added in todays gas, it may now begin to slightly dissolve the sealant & cause fuel problems when running through a heated carburetor.


4. Message no. 156 sounds like a good highway test, but as you cautioned, one hard bump, possible spilled gas on a hot manifold, & then maybe having to dial 911 for a fire truck.


5. Whatever you have, it appears very unique mainly because not many are reporting a similar problem. Maybe try Tom's no. 159 message above -- cannot hurt.

6. Please keep reporting detailed findings, hopefully somebody may think of something else.

[noboD]

When it runs rough and you let it sit to cool do you shut it off? or let it miss and run rough? until it straightens itself out? When running rough have you pulled spark plug wires to see if they are all firing? I'm betting it will be very obvious when you find it.

[Lawrie]

Dont worry,there is another with a very similar problem,he is not on the forum ,but I spent many hours on the roadside trying to coax it home.we have been on many trips with the couple and it seems a similar problem,
I wait with baited breath to see the fix,
Runnerbun travels with us as well so he is familiar with the car and problem,believe me we have tried to sort it out.
Lawrie

[boober49]

Your fuel line is running to close to your exhaust causing fuel to evaporate in the line. Allow enough distance so that line can't get hot.

[boober49]

another old trick i saw my father use was a wooden clothes pin clipped on the fuel line.

[H. L. Chauvin]

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Cheap Pencil Coil Polarity Test:

Because Model A's & Model A repop parts offered today are rather unique, listening to the many experiences indicated in messages given by other Model A owners, (approximately 16 on this thread,) one can see many have reported Model A "coil" problems; e.g. message nos. 13, 23, 30, 31, 34, 37, 38, 42, 59, 64, 65, 68, 101, 109, 115 & 147.

Supposedly, with even a minor breakdown in current flow, coils can get hot & cause ignition problems if polarity is not correct. Marking on coils are useless if marked (+), or (Dist.) or (Bat.) or (Ign.) if the coil was intended for a negative ground battery & the coil is installed on a positive ground battery vehicle -- or vice versa.

Coils can operate if not wired correctly but can lose 15% - 20% efficiency
plus lower gas mileage, & in some cases get hot & cause missing when hot -- after coil cools down, engine runs fine again.

This may or not be the problem, but below is an inexpensive, simple polarity test you may want to try to verify your coil polarity:

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If you are still skeptical about all this, there is a quick way to check directly which way the current is flowing in the high tension circuit. Disconnect a spark wire from a spark plug (or the coil wire from the distributor cap). Hold this HT wire near a grounding point (or near the connector end of a spark plug), and position the tip of a graphite pencil in between. When you crank the engine (no need to start or run) you can observe the resulting spark jump between wire and pencil, and between pencil and ground (or spark plug). A flare (hard to see) toward the plug (or ground) shows correct polarity while a flare toward the coil shows reversed polarity. If the flare goes toward the coil, just switch the primary wires on the coil and make note of the connections for future reference.

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Can't hurt to reach for wood chips when drowning.

[Tom Wesenberg]

I found some white wire wrap at a swap meet. If I get stuck using 10% ethanol garbage gas on a warm day then I slip this plastic tubing over the gas line. It helps quite a bit to reduce the ethanol problems. I keep it under the seat when not needed.

[Tom Wesenberg]

Here is a brief but excellent read about the importance of correct coil polarity.

http://www.chicagolandmgclub.com/tec...neral/574.html

[Mitch//pa]

tom where are your engine pans? that may help it run cooler !!!!!!!

[Tom Wesenberg]

Originally Posted by Mitch//pa

tom where are your engine pans? that may help it run cooler !!!!!!!

They're in the basement, but my car runs great now that I ran 2 1/2 gallons of pure white vinegar in the cooling system for 30 days and got all the rust flakes out of the block and radiator.

[Mitch//pa]

Originally Posted by Tom Wesenberg

They're in the basement, but my car runs great now that I ran 2 1/2 gallons of pure white vinegar in the cooling system for 30 days and got all the rust flakes out of the block and radiator.

Just bust'em. Lol

[JBohannon]

sgwilson, Can you tell me the measurement of the closest point the fuel line is to exhaust or manifold. Thanks, Joe B.

[Old182]

Wow - what a thread! It seems everyone in Model A-dom except me has offered suggestions - and very good ones at that - so here's my experience. This may be a long shot, but another $0.02 can't hurt the pile. We finished our coupe in 1988 and its maiden voyage was from southern NY state to Sturbridge, MA. The car ran great until we got 50 or 60 miles into the trip and it suddenly slowed down and died. With an entourage of experts in our group, we replaced the carburetor with a working one. Twenty minutes later, we were on our way again. Then, another 50-60 miles and same problem. This happened all the way to Sturbridge and even on the local tour. We replaced the distributor (one part at a time) and even put the condenser on the firewall next to the coil (where it's been mounted for the past 25 years without replacement!) but the problem persisted. On the way home from Sturbridge, I disconnected the fuel line for the hundreth time to again check for flow and there oozing out of it was a clear, snotty looking string of silicone caulk. I pulled it out best I could and we were on our way. Later, same symptom, same snot, same cleaning procedure. I had used silicone caulk as a sealer around my fuel gauge and found out the hard way that gasoline dissolves it - in a very slow but deliberate way. A thorough cleaning of the entire fuel system and an in-tank filter screen solved that problem once and for all. My point is that we blew through the fuel line, checked the sediment bowl and did all the "correct" troubleshooting but it was just dumb luck the car decided to have a runny nose at the same time I disconected the fuel line. Don't know if this helps, but if richening the mixture seems to bring the engine back to life, my money's on a fuel blockage somewhere. Good luck!

[H. L. Chauvin]

1. My ethanol experience was with a newly acquired Model A in late 2006.

2. The problem appeared to be my adding ethanol gas in the Model A gas tank, & allowing it to stay in there for 2-1/2 years during partial restoration, while it dissolved my previously "sealed" gas tank.

3. Had no idea what kind of sealer was previously used prior to my acquiring it; however, upon re-starting the engine with ethanol gas & driving only for about (20) miles in my eldest son's wedding, the entire inside of the carburetor & the entire inside of the intake manifold turned jet black with a tar-like goo substance.

4. First tried cleaning the carburetor & intake black goo with paint thinner, then Acetone, next gasoline; however, a mixture of waterbased POR 15 Marine Clean immediately dissolved it, & worked even far better when the water was hot -- one (1) part POR 15 Marine Clean to four (4) parts hot water.

5. Later made up another same batch mix of POR Marine Clean with hot water, added about (2) gallons to the gas tank, rocked entire Model A from side to side, & front to back for about (10) minutes & repeated rocking within an hour. Allowed mix to sit in tank overnight & drained it the next morning whereby the clear thin mix turned black.

6. Repeated paragraph 5. above, but this time when drained, the POR 15 mix was a lot clearer.

7. Followed by filling gas tank to about 1/3 with only hot water for a rinse, shaking vehicle & after draining, the water was quite clear.

8. Allowed the tank to dry overnight, then filled with non-ethanol gas with about (4) ounces of Marvel Mystery Oil.

9. Just was lucky to have an old tank sealer that could be dissolved with a water based cleaning product which was designed to clean oil & grease from oily & greasy metal.

10. So common to read so many reported different Model A experiences.

[Pete Fin]

Try running your vehicle with a different muffler system I had the same problem and tried all suggested remedies but to no avail. The problem gradually got worse. It was suggested to me (by an 80 year old whose first car was a Model A) that I probably had a carbon build up in the exhaust system. I tried an exhaust system off another Model A and drove at 50 -55 mph for 80km (50 miles) and no backfires! I am about to refit the original exhaust system (after "burning out the carbon") and am hopeful that the intermittent, unexpected & until-now-unexplained loud explosions will have ceased. Worth a try!

[MikeK]

There have been at least two posts so far in this thread suggesting an exhaust back-pressure problem. The symptoms certainly fit an intermittent occurance. I could see this for two reasons in an A: 1) an accumulation of those dreaded exhaust manifold seal rings down the pipe, sometimes jiggling into a blocked configuration. 2) Big rust flakes accumulated inside the muffler. When running they randomly fly up and block some holes, eventually too many. After sitting they settle, all is normal 'till it repeats.

[sgwilson904]

Before I get to Follow-up/Update #4, as promised, let me say how much I appreciate that Model A folks seems to have what my mother used to call "the patience of Job." I appreciate you all sticking with me here and continuing to come up with ideas as we struggle to solve this mystery. Your suggestions, coupled with the help from the guys here in the Jacksonville A's, is keeping me at it.

My pal Mike, an old Navy vet (in the military service, not the store at the mall) has two A's of his own and he's been helping me implement some of the suggestions posted here. I'm surprised he hasn't yet suggested we drive the thing off a pier and see if it floats but he helped me work on it again yesterday and there are some new developments to report.

A couple of days ago, I noticed a few drops of gasoline dripping onto the floorboard from the sediment bowl fitting against the firewall. In tightening that, we noticed there appeared to be no silicone tape or liquid sealer applied to the threads. On the ride home, I discovered our tightening had increased the problem and now there were several drops on the floor. I turned off the fuel valve, ran the engine until it stopped and let it sit overnight which temporarily suspended the link.

Yesterday, we removed the inside fuel lines and found some silicone on one end of the threads but not the other. When we also removed the sediment bowl fitting for closer inspection, we discovered someone had once cross-threaded the threads of the inside fuel line connection. We replaced the fitting with a new one, using the liquid sealer instead of silicone tape on both ends. That solved the leak...but on a test drive, Mike determined the carb was running a little rough and we ought to swap it out to see if THAT is part of our big problem.

Once we removed the carburetor, we noticed just inside the fuel line was some white, stringy junk we took to be silicone. It wasn't clear if this was from the threaded fitting on the carburetor itself or whether this had come from inside the fuel line farther upstream. We dug all of it out, opened the carb to assure there was not any more inside, then put it back together. This seems to be right in line with the suggestion of Old 182's experience posted above (#173).

Now, with a leakless fuel connection and all silicone tape removed from all fuel line fittings (replaced now with the liquid sealer) and string stuff all cleaned out of the carb, we're ready for another long test drive today.

Recent posts that suggest hot fuel lines causing vapor lock--see #164, 167 and 172 above--led me to another discovery I've never thought about.

My fuel line from the firewall to the carburetor does not seem be too close to the engine at any point. JBohannon (post 172) asked for an exact measurement. The closest point is 3 inches from the manifold. I've posted a picture below. But in examining this, I also notice that my fuel line appears to be BRASS and not the STEEL lines most cars use and is sold by the parts houses.

My Internet research shows brass to be a better conductor of heat than steel, perhaps as much as 10 times more conductive. Could this play a role as a contributory factor if not a causative one? This is another cheap fix I could try if you all think it's a likely problem.

Finally, speaking of fuel line, let me also respond to the clothespin idea from Boober49 (post #165 above). Back in the hottest days of the summer when everybody in the club was convinced this was vapor lock pure and simple, we put enough clothespins on that line to hang two week's worth of laundry! They were cheek-by-jowl along the entire length...but did nothing more than provide much comic relief from some of our veteran members who were sure I was an idiot. And of course by now, I've given them much more evidence to support THAT point of view, haven't I?

So, when it warms up here a little, I'm off down the road to St. Augustine again to see how it runs post-cleaning the silicone crap. I'm hoping Old 182 might be onto something. If not, I'll drive 40 miles to fill up on pure, no-ethanol gasoline and try that, too.

[Tom Wesenberg]

No sealers should be needed for Model A fuel lines. I did have to tin the flare on an inside line one time to fix a slow drip.

[JBohannon]

sgwilson, I do not know if the brass fuel line is causing the problem but I can say I had the same problem and yes my fuel line was copper. Joe B.

[1931 flamingo]

Off topic but my Mom used to live in St Augustine, got to be one of the most beautiful places in the country. Many good memories.
Paul in CT