rebuilt 400 quits running
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Joined: Apr 2004
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rebuilt 400 quits running
First off...GREAT site--this is my first post. I have used a lot of the info while rebuilding a 400 for my 77 highboy. I have searched the posts but I have yet
to find a similar situation as this:
After rebuilding the motor, it started up just fine and has run great for the last 200 miles. As of late, it quits running. It will start up and run for about 10+/- minutes before it dies out. I thought it was my ignition module, so I replaced it as well as my ignition switch. Still, it stops running after about 10 minutes. When I try to restart it, it seems as though it is not even getting a spark--it seems to want to fire as I release the key from the 'start' to 'run' position. When I rebuilt the motor, I replaced the distributor, cap, rotor, coil, wires, spark plugs, fuel filter, fuel pump, alternator and added headers. I did tap into the green wire (going to the coil) for a tach, but other than that it is how it was before I rebuilt it. After I let the truck sit/cool down for 15 minutes, it fires right up! I checked all the connections and everything seems to be secured. Before I start replacing all the other new parts, I thought I would see what your suggestions are.
Thanks.
to find a similar situation as this:
After rebuilding the motor, it started up just fine and has run great for the last 200 miles. As of late, it quits running. It will start up and run for about 10+/- minutes before it dies out. I thought it was my ignition module, so I replaced it as well as my ignition switch. Still, it stops running after about 10 minutes. When I try to restart it, it seems as though it is not even getting a spark--it seems to want to fire as I release the key from the 'start' to 'run' position. When I rebuilt the motor, I replaced the distributor, cap, rotor, coil, wires, spark plugs, fuel filter, fuel pump, alternator and added headers. I did tap into the green wire (going to the coil) for a tach, but other than that it is how it was before I rebuilt it. After I let the truck sit/cool down for 15 minutes, it fires right up! I checked all the connections and everything seems to be secured. Before I start replacing all the other new parts, I thought I would see what your suggestions are.
Thanks.
Senior User
Joined: Oct 2003
Posts: 347
Likes: 0
From: in a house
it should be 400-800 ohms.
a hair line crack in the pickup coil will work while the engine componets are cold and then when it heats up it will separete just enough to loose signal to the ignition box and will terminate power to the coil cuz it thinks the dist is not rotating.
just use the troubleshooting guide for the ignition system out of a chiltons book if you have any problems.
a hair line crack in the pickup coil will work while the engine componets are cold and then when it heats up it will separete just enough to loose signal to the ignition box and will terminate power to the coil cuz it thinks the dist is not rotating.
just use the troubleshooting guide for the ignition system out of a chiltons book if you have any problems.
Senior User
Joined: Feb 2004
Posts: 379
Likes: 1
From: Delavan, IL
Vapor lock???
I am going to assume that you've actually checked the spark via a tester or screwdriver and ground. If not, I would say start there. If that checks out, I would take a look at your fuel lines. It sounds to me like something (ignition or fuel) is getting hot and causing problems. You can try wrapping your fuel lines with insulation and putting a spacer between your carb and intake. These two measures will actually give you a very slight bit of help on power too. Good luck though.
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
How is your fuel filter? A blocked fuel filter can do things like that. Pump your accelerator pump on the carb right after it quits to see if it squirts fuel. Other than that it is probably electrical.
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