Big mystery finally solved...and who deserves the prize?

[sgwilson904]

About six weeks ago, I posted the thread “Who Can Solve This Mystery? Win a Prize?” Astoundingly, it was viewed more than 11,000 times and more than 200 of you wrote replies with suggestions to solve the problem that was causing my 29 CC P/U to intermittently sputter, backfire and fail to run more than about 6 mph. Sometimes it started up and ran just fine, most of the time it did not. You could never depend on it to get you there—and back.

First, thanks to all of you who pitched in with ideas. As I reported (and will discuss in detail below) several fellow club members spent many hours trying our best to follow all your suggestions, except Brent’s ideas to check for loose lugnuts on the left rear wheel and make sure the radiator coolant had the proper mixture…those were jokes, right?

After weeks of trying virtually everything, we were just never able to identify the real problem and resolve it. In sheer desperation, I finally turned it over to the fellow many of us call “The Guru” here in our local club in Jacksonville, FL. H.L. Chavin would call him a “Model A Whisperer” with the patience and know-how to sleuth out the problem.

I’m happy to report that it appears the mystery has finally been solved! And so what was it?

According to "The Whisperer": The grounding strap from the battery to the frame was not always providing sufficient ground to provide ample and consistent juice to the distributor. Sometimes it worked just fine—like on my long drive to coastal Georgia where the truck ran fine for 110 miles before it suddenly started acting up—and then other times you couldn’t even get the thing to start.

The local whispering guru says a continuity test with a meter confirmed this. (For the benefit of us all who have experienced a similar perplexing problem, he’s planning to write a more-detailed explanation later here in this same thread.)

So what about the prize I offered in my total frustration to find the answer? Who should get the prize?

Turns out, after scouring all the suggestions previously posted, it’s not so easy to select the winner. Without sending you back through 20 dozen postings, here are the people who got CLOSE to identifying the problem.

The g-word was actually first used in Post #4 by “Brent in 10-uh-C” who suggested checking for a blue spark from the coil wire to a ground source when the engine cranks. This didn’t resolve it because we GOT the spark when the ground strap was working okay and the engine was running as it should.

In Post #19, “Modelacoupe3” suggested a ground problem caused by the wire to the upper plate of the distributor. We changed that but no ground problem there. Eventually, we even dropped in an all-new distributor and still the engine didn’t run right.

Then, in Post #41, “Mike V,” a senior member from South Florida, wrote on January 27: “Grounding to the engine.” He went on to guess the fuel line was acting as an engine ground which was conducting heat to the extent it was causing the fuel to turn to vapor. Although he clearly mentioned grounding, we took it to be a contributing factor to "the real problem" which he believed to be the dreaded vapor lock. He suggested “place a cable from the chassis to the engine and see what happens.”

On the same day, “MikeK” from the Windy City offered a host of suggestions to ascertain whether root of the problem was fuel or electrical. In his paragraph on electrical, he wrote: “You may also experience that type of behavior if you are running on straight generator, with the connection to the battery lost.” He went to suggest: “Remove/clean- frame to ground strap bolt, both battery terminals, heavy cable to starter, wiring from cutout to starter switch, wiring to terminal box” and maybe, he suggested, there could even be a problem with internal connections between cells inside the battery. But since I long ago replaced the generator with an alternator, we didn’t think Mike’s hypothesis was valid in this case.

After 101 posts, “Mike V” in Florida, recalled and summarized many earlier suggestions and asked if those were followed, including. “Was the ground to the engine checked?” Mike was sure “We can get this!” We kept on looking.

24 posts later, H.L. Chavin hit on the ground problem again, but we all got a little sidetracked because his theory was presented in the context of bad grounding causing vapor lock as the real heart of my problem. H.L. said this could be checked by splicing a short piece of rubber hose into the fuel line, ostensibly to reduce heating the fuel in the line. We replaced the copper fuel line with a steel one but problem continued. A few posts later, he also asked “possible new painted engine blocking ground?” Nope, paint wasn’t my problem.

Later, H.L. did suggest adding a second ground strap (again as another possible step to resolve a vapor lock). Here again, I was sidetracked because the engine would often run just fine for a prolonged period. None of us could see how vapor lock that was caused by lack of ground (or anything else) could be my problem.

And then, on March 1 (Post #236), Rock Hornbuckle in Auburn, Washington jumped into the dispute about whether the coil needs a ground. It was in that context he suggested: “With an ohm meter, check the readings between the engine/frame, engine/coil should read open, engine/battery ground post, battery ground post/generator ground. If all the readings are the same, you don't have a grounding problem. Do these checks cold, then do the checks when the engine is hot and quits.”

Rock went on to sound a little like my college physics professor (gawd, I hated that class) but added an explanation of how this problem could have caused my problem to be so intermittent: “I know this sounds crazy, but electrical resistance in your engine block and wiring changes with temperature. If you have any bad wires (thinning through age) the slightest heat rise will affect its current carrying capabilities. The same holds true for any bad or loose or intermittent ground connections.”

The Whisperer here has taken the truck on a long drive to St. Augustine. He reports it ran just fine except for some brief sputtering which he says was crap in the fuel and once that was out, it resumed running as it should.

Hoping it is finally no longer possessed, I'm picking it up and taking it on a club tour event this coming Sunday. I'll report how it does on my test-drive! Meanwhile, watch for the more-technical details of what got me back on the road. I think it could be a big help to many.

Now, as to the prize:

Brent log ago suggested an ARC (Answer Review Committee). So what do y’all think? Who deserves the prize? And what should it be? How about the old ground strap that looks like it WAS the heart of my problem?

As always, suggestions warmly welcomed...and thanks again to all of you for your patience!