73 Wont fire

[Matt4397358]

Hi all, I have my grandparents old 73. I replaced the entire wiring harness a few years ago, but after sitting for about a year, the engine turns over but won't fire. The spark plug has spark, just dont know where to go from there. If anyone has any ideas, or knows someone around the Pittsburgh area that works on them, let me know!

 

[CaptainShwammy]

Only 2 things needed to make an engine run, fuel and fire. If it's been sitting for a year maybe the carb is dirty. Maybe the fuel isn't turned on at the petcock. Hopefully the latter is the problem, but either is a fairly easy fix. If the fuel is on see if you can start it with starting fluid. Just open the filter housing and spray it directly into the carb with the choke off. Just a quick shot though, too much or it will over rev and blow the motor. Lots of times just getting it going with starting fluid can pull the gunk out and get the gas flowing.

 

[Matt4397358]

Only 2 things needed to make an engine run, fuel and fire. If it's been sitting for a year maybe the carb is dirty. Maybe the fuel isn't turned on at the petcock. Hopefully the latter is the problem, but either is a fairly easy fix. If the fuel is on see if you can start it with starting fluid. Just open the filter housing and spray it directly into the carb with the choke off. Just a quick shot though, too much or it will over rev and blow the motor. Lots of times just getting it going with starting fluid can pull the gunk out and get the gas flowing.

Will definitely try that.
When we tried to start it earlier, there was gas coming out of the filter housing, can that be a result of one of those?

 

[rfunk]

Too much gas (flooding) can also result in no start. If the plug is partly dirty, AND wet, it may not fire in the cylinder, but may when you are "testing" it for spark, laying on top of the head . . . dirty points can also cause a weak spark. I've had to dry out car engines whose owners flooded them in winter - used the air compressor through the spark plug holes to get rid of the excess gas. FRESH gas is also important if it's been standing. If the gas smells stale, drop the carb bowl, flush tank and line with fresh fuel. (take appropriate fire safety precautions!!)

 

[mgonitzke]

THREE things are needed: spark, fuel, and compression, and the spark has to occur at the correct time.

If fuel is pouring out of the air filter, it is probably time for a carb kit. Clean the carb, install the new parts, set the main needle to 2 1/8 turns out and the idle to about 1 3/4, which should allow you to start it, and then you can fine tune from there.

 

[CaptainShwammy]

Compression is a given. It's an engine that ran when it was last parked. By this THREE things mess you might as well bump it up to 50 and list every silly thing that happens in an engine.

 

[CaptainShwammy]

Sounds like your float is stuck. The main jet needs cleaning. I'd suggest cleaning all the jets and run a piece of stranded wire though them to make sure they are clean. Should fire right up. If not, then open up the rabbit hole of compression/timing issues.

 

[mgonitzke]

Compression is a given. It's an engine that ran when it was last parked. By this THREE things mess you might as well bump it up to 50 and list every silly thing that happens in an engine.

Definitely not a given. More than once I've had a valve stick open on an engine that has been sitting for a period of time.

 

[jbland]

I would say a valve is stuck open

 

[mgwin]

There are many issues that could be the problem. Since Matt4397... stated the plug has fire, I would look at fuel issues as most have already stated.
Being parked a year ago, and no mention of using non-ethanol gas, I would almost bet the fuel has lost it's intended purpose; to burn. I have heard of instances where gas went bad in as little as 30 days!
Not to mention what ethanol will do to a carb.
OK, .........I will tell what it will do. It will create little crystals kind of like salt or sugar that will stick everywhere, including inside the carb.
Before I get criticized too much, remember, I am talking about straight regular ethanol gas that has no kind of additives.
As for the carb, my experience has been, the engine will not run like it ought to without a thorough cleaning and a kit installed as Matt G. suggested. As for the gas coming out of the breather, I would say those crystals have blocked the needle from seating.