Ignition help

[GarageRat]

I am out of ideas and would like to hear if anyone has any suggestions. I was driving my 1976 Fiat Spider a couple of weeks ago and suddenly when I turned into my neighborhood the engine just stalled when I pushed in the clutch while making a turn. It would not restart when I let out the clutch. There were no symptoms beforehand, but it would not restart once I had pulled over. After trying to crank it a bit it actually spit out the carb. I towed it home and checked the timing belt, turned the engine by hand to ensure timing marks were still lined up. I have a crane electronic ignition kit installed inside the stock 1976 distributor and have run it for 3 years without an issue. I took it out and put a new set of points and condenser in, same result. I replaced the coil, cap, rotor, plugs, wires, and the mechanical advance springs, ran compression check to check for valve train issues, all were 150-155 psi. The distributor shaft seems to have a very slight (maybe a mm or 2) rotational movement but no wobble. I checked and rechecked static timing with cap off and it is still set to 10 degrees BTDC as before. I cleaned the contact for the battery ground. I verified 12v at the coil with the key on and the crane unit uses a ground to the body, I verified it was grounding, and from my multimeter it also appears that the stock ground for points also is grounding. It still acts as though it is misfiring or arcing, with weak sputtering and spitting back out carb. The plugs are wet with fuel after cranking for a while so seems to be getting fuel. When I use a timing light it seems like #1 fires correctly at 10 deg BTDC, and I don’t have a mark for cylinders 2 and 3 but the light goes off at what appears to be 180 degrees opposite. I admit that #4 doesn’t seem to set off the light with any regularity, so it could be the source of the misfire but it would have to cause the other cylinders to pick up that charge instead. Any ideas?

[18Fiatsandcounting]

It kinda sounds to me like the engine might be flooding. Not sure how it got that way, but try this: Make sure your battery is charged, hold the gas pedal to the floor, and crank for 5 or 6 seconds at a time (so as not to heat up the starter). Don't pump the gas pedal, just hold it wide open. See if it fires.

If it was flooded, the likeliest issue is a leaking float valve on the carb or improper float level adjustment. Yours has the 32ADFA carb, yes?

-Bryan

[GarageRat]

It is the 34 dmsa, which now that I think of it has a problem developing cracks inside. That could be it

[18Fiatsandcounting]

If you find the issue is with the 34DMSA, and want to sell it, let me know as I could use it for parts. Send me a PM if you decide to junk it.

-Bryan

[GarageRat]

Bryan,

Unfortunately it doesn't appear to be the carb, as after letting it sit and cleaning off spark plugs then cranking it doesn't result in flooded cylinders. I will recheck spark again at each cylinder later.

[GarageRat]

Bryan,

I found the problem- the plug that seals one of the vacuum ports on the intake backed itself out and literally fell out. I didn’t think to consider a giant vacuum leak, but I put in a bolt that has the same thread pattern and it started up. Thanks for the help

[18Fiatsandcounting]

Awesome, GarageRat! Let us know if there are any other issues, and hey, if you ever decide to sell that 34DMSA carb, you know where to find me.

-Bryan