1953 M38a1 Hard start, engine stumble
Posted: Sun Oct 30, 2022 12:27 pm
Hi everyone,
Sometimes engine turns over but won't start and on other days she will fire up. She can run like crap one day and another day she will run ok but with an occasional stumble.
On days she won't start at all, I can remove a spark plug and put a little gas in the cylinder and she will fire up. Engine will run albeit with a stumble every now and then.
Choke inspected and works and is fully choked when I try and get a no start.
Here is some background in case it is relevant:
All spark plugs replaced.
New cap and rotor.
New ignition coil.
Running 24v with Pertronix.
Carburetor is the original model and was a rebuild from Army Jeep Parts but has been opened and inspected by a local shop for blockages from possible fuel contamination. (all fuel lines replaced and fuel filter now installed).
Fuel pump was rebuilt by local classic car shop but it appears to be leaking oil.
Timing has been checked. At operating temp, she is running a little advanced. About an inch away from 5 degree mark. I can't physically turn the distributor any closer.
Compression test ran last week. All between 100-110#. Wet compression test increased the numbers only slightly all going up anywhere from 2 to 10#.
I've run across comments here talking about vacuum lines from the fuel pump can affect rough idle. Is this worth giving a hard look at?
I appreciate any help, thanks!
Sometimes engine turns over but won't start and on other days she will fire up. She can run like crap one day and another day she will run ok but with an occasional stumble.
On days she won't start at all, I can remove a spark plug and put a little gas in the cylinder and she will fire up. Engine will run albeit with a stumble every now and then.
Choke inspected and works and is fully choked when I try and get a no start.
Here is some background in case it is relevant:
All spark plugs replaced.
New cap and rotor.
New ignition coil.
Running 24v with Pertronix.
Carburetor is the original model and was a rebuild from Army Jeep Parts but has been opened and inspected by a local shop for blockages from possible fuel contamination. (all fuel lines replaced and fuel filter now installed).
Fuel pump was rebuilt by local classic car shop but it appears to be leaking oil.
Timing has been checked. At operating temp, she is running a little advanced. About an inch away from 5 degree mark. I can't physically turn the distributor any closer.
Compression test ran last week. All between 100-110#. Wet compression test increased the numbers only slightly all going up anywhere from 2 to 10#.
I've run across comments here talking about vacuum lines from the fuel pump can affect rough idle. Is this worth giving a hard look at?
I appreciate any help, thanks!