Backfiring

[John Mc]

So it was the ignition coil. Replaced that and it ran. For 20 minutes. Now it won’t start again.

Hopefully what ever is going on did not fry your replacement ignition coil

 

[Carpartz88]

Ok folks I just got this 1952 M37 it’s backfiring a lot and wants to sputter out when I give is and throttle. Any suggestions.

It was the ignition coil. Ran for 20 minutes 2 times now it won’t fire again.

 

[Carpartz88]

Hopefully what ever is going on did not fry your replacement ignition coil

so it has 2 batteries in the that aren’t the same and kinda old. I wonder about them

 

[G744]

The batteries need to be the same, for if one has a different Ampere-hour rating, it will cause one to charge over 12V and the other will never charge up properly.

 

[booze_rooster]

Is it backfiring through the intake or the exhaust pipe?

All that cranking and not starting is dumping that fuel somewhere. Where it ends up is a good indicator of what's happening.

I'd say to eliminate the tank and bad gas variables get a 5gal plastic boat tank and put fresh gas in that. Hook it up to your fuel pump inlet and pull from that. You could even put an inline electric pump and regulator and hook it directly to the fuel line port on the carb to bypass the mechanical pump.

"Rebuilt by previous owner" means nothing. I just worked on a customers 1951 Jeepster with an F134 supposedly rebuilt by a "master mechanic in a barn in Ohio". Leaked like a sieve from the oil pan where two bolts were snapped, Cylinder 1 and 4 plugs were gapped too close and the number 4 exhaust valve was too tight. Battery ground was a piece of speaker wire. Bad oil pressure sender and a rotten exhaust manifold glued on with the orange goop.

 

[Carpartz88]

Well you need to start doing some detective work. Pull the dist cap and check the points if good lube the shaft and set the points for .018". Next disconnect one of the spark plug wires and with a spare plug see it you are getting a hot spark (running) so you know the coil is ok. How long has the fuel been in the tank? Check the fuel filter to see if it is plugged up. I'm remembering from many years ago but there is a ballast resistor on the firewall and they can break or the connections can rust up. Dribble a little fuel down the carb while running the throttle cable by hand to see if you get an improvement. Baby steps.

Mark

Is it backfiring through the intake or the exhaust pipe?

All that cranking and not starting is dumping that fuel somewhere. Where it ends up is a good indicator of what's happening.

I'd say to eliminate the tank and bad gas variables get a 5gal plastic boat tank and put fresh gas in that. Hook it up to your fuel pump inlet and pull from that. You could even put an inline electric pump and regulator and hook it directly to the fuel line port on the carb to bypass the mechanical pump.

"Rebuilt by previous owner" means nothing. I just worked on a customers 1951 Jeepster with an F134 supposedly rebuilt by a "master mechanic in a barn in Ohio". Leaked like a sieve from the oil pan where two bolts were snapped, Cylinder 1 and 4 plugs were gapped too close and the number 4 exhaust valve was too tight. Battery ground was a piece of speaker wire. Bad oil pressure sender and a rotten exhaust manifold glued on with the orange goop.

so I replaced the ignition coil. And it fired up ran for 20 minutes or so and quit. Wouldn’t start until the next day and ran for 5 minutes. Now it won’t start again. What. Oils possibly burn up ignition coils

 

[Justin7up]

I use a $3 clear acrylic tube when diagnosing an engine for the first time so I visually see there's no gaps in the flow of gas from the pump failing or the hose not being at the bottom of the tank.
Remove the air cleaner and watch the carb are you leaking any gas or not getting enough gas. Gas pissing out you might need a full carb rebuild or your timing might be way off.
If idle dies out you might need to increase your idle jets

 

[OutpostM37]

Where gas gets into the oil it means your stock fuel pump diaphragm has failed. Either age or the new gas eats it up.

This is why many, many have gone to an electric pump back by the gas by the gas tank to push the gas rather than pull it. This really cuts down on vapor locking as well.

Best thing I ever did.