why will it not start
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Tuned
Joined: Dec 2017
Posts: 353
Likes: 6
From: Arkansas
why will it not start
1951 239 flathead
Carb has been rebuiltNew fuel pump
New plugs,( gapped at 25), new points,cap and rotor
New plug wires
2 valves were stuck got them freed
Power through the coil to the plugs
Fuel to the carb
New fuel lines
Can see gas coming out of fuel pump and have taken fuel line to carb loose and fuel is going to carb
Have cleaned the gas tank
Have checked the intake manifold everything appears Ok
Have taken the plugs out and turned the engine and getting about the same pressure out of each cylinder
The intake manifold was my last thought and like I said all appears well with it
In an attempt to start it I run a wire from the positive side of the battery to the positive side of the coil so if all is well it should start.
Any help greatly appricated!!!
Fleet Owner
Joined: Jul 2004
Posts: 27,300
Likes: 1,059
From: NM
I wouldn't stick a screwdriver in there! The piston isn't under the spark plug hole.
49's question about whether it pops is the key; you say you have "spark to the plugs"? if that is true, it is likely a timing issue. Put the pointer on the front timing cover to align with the dot on the crank pulley. Look thru the #1 spark plug hole and see if the piston is at TDC. If it is, then crank the engine with the #1 plug out, and your thumb over the hole. Stop cranking when the pressure pushes your thumb off. Rotate the crank back so the point and dot align (should be very little). See if the rotor is pointing to #1 or is 180 deg from it.
49's question about whether it pops is the key; you say you have "spark to the plugs"? if that is true, it is likely a timing issue. Put the pointer on the front timing cover to align with the dot on the crank pulley. Look thru the #1 spark plug hole and see if the piston is at TDC. If it is, then crank the engine with the #1 plug out, and your thumb over the hole. Stop cranking when the pressure pushes your thumb off. Rotate the crank back so the point and dot align (should be very little). See if the rotor is pointing to #1 or is 180 deg from it.
Thread Starter
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Tuned
Joined: Dec 2017
Posts: 353
Likes: 6
From: Arkansas
Nope, I even have taken to spraying a little carb cleaner into the carb to see if that could get it to pop without success. This is what leads me to think the intake manifold was clogged as the engine did not have a carb when I bought it. Thought maybe darned mud daubers had built a nest inside of it.
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Tuned
Joined: Dec 2017
Posts: 353
Likes: 6
From: Arkansas
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Mountain Pass
Joined: Sep 2017
Posts: 235
Likes: 25
From: Solvang CA
My thought is that something is in backward, or reversed, or switched, or left hand is right hand, or upside down, or 180 degrees like Albuq says.
Have a nice 4th of July. Let the truck be. Come back with fresh thoughts.
Have a nice 4th of July. Let the truck be. Come back with fresh thoughts.
Hotshot
Joined: Jan 2001
Posts: 16,894
Likes: 3,136
From: SE Wisc. (the Rust Belt)
What kind of compression are you getting from all cylinders? Duane helped me with a problem I had with the flat six in my F-2. I changed everything and still would pop over. My flat six is an old engine and has low compression but still would run but wouldn't run after sitting for about a month. Duan, I think, I had a group of guys over that night and someone suggested hooking the truck to the back of my daily and giving it a pull down the driveway. Within about 30 feet I popped the clutch and the truck started and has been running since. The rings compressed and the engine lost most of the compression but by spinning if fast while pulling the low compression was overcome. Once warm the rings expanded and compression went up.
I also had another truck with a flat six and it would spin over and pop and back fire. I checked the distributor and it was 180° off. Took it out, rotated and it fired right up.
Also check the wire from the coil to distributor. I've two of these break in two different trucks. One minute they were running fine, parked them for a short period of time and went out to go home and they wouldn't start.
I also had another truck with a flat six and it would spin over and pop and back fire. I checked the distributor and it was 180° off. Took it out, rotated and it fired right up.
Also check the wire from the coil to distributor. I've two of these break in two different trucks. One minute they were running fine, parked them for a short period of time and went out to go home and they wouldn't start.
Thread Starter
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Tuned
Joined: Dec 2017
Posts: 353
Likes: 6
From: Arkansas
Appreciate all of the info, will try all of your suggestions all else fails, I think I will take electric maniac's advise. That being leave it alone for the day and enjoy the fourth. Adult beverages come to mind
Thread Starter
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Tuned
Joined: Dec 2017
Posts: 353
Likes: 6
From: Arkansas
I had an idea and boy did it hurt, L! What about taking a syringe and shooting gas into each cylinder and if the motor fires it tells me that the carb is not getting gas to the cylinders?
Hotshot
Joined: Jan 2001
Posts: 16,894
Likes: 3,136
From: SE Wisc. (the Rust Belt)
Look down the throat of the carb and pull the throttle on the side. You should see gas getting sprayed into the throat of the car. This will tell if gas is getting pumped into the intake.
