After 10 years of inactivity of 59 AB on my 46 Merc with 3,000 miles on a 40 year old rebuilt engine, just installed rebuilt (Bubba) distributor, new condenser, cap, rotor, fuel pump, coil & carb. Also have fuel filters before fuel pump and between fuel pump and carb. I know I am getting good fuel flow to carb. Have checked & re-checked all connections, spark plug wires, etc. Engine has difficult time starting but when it does I hear a sucking sound from the carb and get a backfire through muffler. After engine starts it sometimes runs for 30 minutes at a fast idle, purring like a kitten. Then it just stops. Sometimes it runs for 30 seconds and just stops. I haven’t had the confidence to take the car out of the garage & don't want to blow a hole in my muffler. Have interchanged (spare) carb, (spare) coil and (spare) distributor & condenser with same result. What am I missing? Don't think it is a fuel issue. Have read all the threads on backfiring but still have no clue.
59 AB backfire at start & other mysteries
- Thread starter psogden
- Start date
FlatheadTed
Well-known member
I have just been through this, check if there is a heat riser hole in the manifold under the carb if so its got the wrong manifold on it or you can cover the hole up ,check the spray nosels in the carb ,Ted
TerryOH
Well-known member
Put a voltmeter on the wire from ignition switch to coil to engine ground and see if your loosing voltage to the coil. You may have a bad ignition switch or ignition resistor. If you loose voltage when it stalls check both. If the voltage comes and then goes then comes back it could be the cause of the backfire. If you install a temporary jumper across the resistor and everything is then good it would appear the resistor needs to be replaced.
I have a '46 Merc. Started the other day with a bang! Ran horribly when I took it out for a run, wanted to die out. Skip overhauled original coil. Old Ford mechanic here says could probably be the condenser, since all else has been checked and overhauled. Engine overhaul 2010, with less than 2000 miles since then. Use Champion H-10, but have purchased Motorcraft AL7C 216 which some recommend. Anybody out there with same problem and a solution? Thanks
Make sure you have around 4.0 volts to the wire on the top of
the coil when running. If it is low it will be a little hard to start.
Below 3.5 it will be hard to start and could miss.You could both
have sticky valves. Drizzle some MMO down the carb while running.
It is best to send a couple condensers to Skip when having a coil
rebuilt. He checks them at no charge hot and cold or install a
IH-200 from Napa. G.M.
the coil when running. If it is low it will be a little hard to start.
Below 3.5 it will be hard to start and could miss.You could both
have sticky valves. Drizzle some MMO down the carb while running.
It is best to send a couple condensers to Skip when having a coil
rebuilt. He checks them at no charge hot and cold or install a
IH-200 from Napa. G.M.
rotorwrench
Well-known member
Valves can get sticky after long slumbers. If an exhaust valve sticks open, it can after fire into the exhaust. An intake stuck open will blow compression back through the intake manifold. Any stuck valve on a cylinder will cause a dead cylinder or miss. Intermittent sticking can be a hard one to diagnose sometimes. A compression test will usually tell the story.
Re: 59 AB backfire at start & other mysteries revisited
Dear Ford Barners,
Solved the backfiring problem (spark plug wires crossed). However--now when I start the engine, it runs very smoothly (literally purrs--no missing whatsoever) sometimes for about a minute and sometimes less. Then, it just peters out and stops. Usually, it will start again right away--but always quits after a short time. Because the engine runs so smoothly, believe sticky valves can be ruled out. Have checked for vacuum leak (found none). Am getting good flow from fuel pump. Have changed coil, condenser, distributor, and carburetor--always with the same result. Have checked heat riser. Have not checked for faulty ignition switch or resistor but that's about all that's left. Do I need to replace the ignition circuit wiring? This now "feels" like an intermittent electric flow issue more than anything. Comments welcomed. Thanks.
Dear Ford Barners,
Solved the backfiring problem (spark plug wires crossed). However--now when I start the engine, it runs very smoothly (literally purrs--no missing whatsoever) sometimes for about a minute and sometimes less. Then, it just peters out and stops. Usually, it will start again right away--but always quits after a short time. Because the engine runs so smoothly, believe sticky valves can be ruled out. Have checked for vacuum leak (found none). Am getting good flow from fuel pump. Have changed coil, condenser, distributor, and carburetor--always with the same result. Have checked heat riser. Have not checked for faulty ignition switch or resistor but that's about all that's left. Do I need to replace the ignition circuit wiring? This now "feels" like an intermittent electric flow issue more than anything. Comments welcomed. Thanks.
Capt Kirk
Well-known member
My gut feeling after your last post is fuel. Can you start it and when it starts dying...squirt a little fuel in the carb to see if that lights her back up? If it does, then fuel supply is your problem. You can temporarily jumper the resistor to see if that makes a difference and you can bypass the ignition switch to see if that makes a difference too.
FlatheadTed
Well-known member
Hot wire it ,Bat to coil /or bat to resistor ,test drive it
Will give those things a try. Thanks
Will try those. Thanks.
Many thanks to those of you who took time to help me with my “issues”. The problem was the 70 year old fuel line from the gas tank. I installed a new copper plated steel line (not any easy task to properly bend) and “bingo”—problem solved.
The ID of a ¼” line is quite small to begin with. This ID was surely compromised by years of moisture and rust particles which were probably clinging to the sides of the line, and I suspect there is a clog somewhere in the line although I don’t intend to do a postmortem. The engine now purrs like a kitten.
Capt Kirk, who diagnosed my problem as a fuel issue & others who thought it was a fuel issue, got it right. You guys know your stuff. Took the car for a quick spin without incident. At one point I thought engine had died but it hadn't--just couldn't tell because the idle was so smooth and quiet.
The ID of a ¼” line is quite small to begin with. This ID was surely compromised by years of moisture and rust particles which were probably clinging to the sides of the line, and I suspect there is a clog somewhere in the line although I don’t intend to do a postmortem. The engine now purrs like a kitten.
Capt Kirk, who diagnosed my problem as a fuel issue & others who thought it was a fuel issue, got it right. You guys know your stuff. Took the car for a quick spin without incident. At one point I thought engine had died but it hadn't--just couldn't tell because the idle was so smooth and quiet.
