[tcromwell35]

Hello everyone I am looking for any insight. I have a 1973 Cougar XR-7 with a 351C. It was running fine but out of the blue it will start when cold and then fast idle at around 1200 to 1500 RPM. I can let it run at fast idle for a few minutes but as soon as I tap the gas to get it to stop fast idling the RPM’s drop and then the engine dies. After that I can’t get the engine to restart. I’ve been toying with the idea of replacing the gas tank (which I suspect is long overdue) along with a new fuel pump but I don’t know if that would have anything to do with this. I wouldn’t think so as it will start cold and fast idle for a good bit before it dies. Thanks as always for any ideas!

 

[catman]

I would check four things to start.
Carb float
fuel filter
Vacuum advance for vacuum.
coil

 

[Ebrig14]

Hello everyone I am looking for any insight. I have a 1973 Cougar XR-7 with a 351C. It was running fine but out of the blue it will start when cold and then fast idle at around 1200 to 1500 RPM. I can let it run at fast idle for a few minutes but as soon as I tap the gas to get it to stop fast idling the RPM’s drop and then the engine dies. After that I can’t get the engine to restart. I’ve been toying with the idea of replacing the gas tank (which I suspect is long overdue) along with a new fuel pump but I don’t know if that would have anything to do with this. I wouldn’t think so as it will start cold and fast idle for a good bit before it dies. Thanks as always for any ideas!

With the engine starting when cold each time but not after warm is not the fuel tank sounds more like a carb/choke issue of carb in general. After the engine has warmed up is the choke butterfly open. When it gets warm and you tap the pedal can you tap the pedal again immediately to keep it running?

 

[jessebrobbins]

I had that issue before, I disconnected the choke and wired it open till I could replace it. Just have to pump the gas a few times before starting when cold, and hold your foot on the throttle for a minute till it will idle on its own.

 

[Ebrig14]

Do you have to wait for it to cool off for it to restart?
Does the carburetor have the idle solenoid on the side with 1 wire going to it?
That is what was used to set the idle speed with key on and close the throttle plate when key is off, this was to prevent idle run on when engine was hot and ignition off. What would happens is the hot carbon in the cylinder would fire the fuel (kind of like a diesel engine) . One way to check it is to remove the air cleaner , turn the key on, move the throttle off idle at the carburetor or watch while someone presses the accelerator pedal slowly, the solenoid plunger should move out if it doesn't this could be your problem. Good luck!
Ed

 

[Jims69]

Did you solve this problem? I have the same issue, and would be interested in what you found.

 

[72cougar]

Hello everyone I am looking for any insight. I have a 1973 Cougar XR-7 with a 351C. It was running fine but out of the blue it will start when cold and then fast idle at around 1200 to 1500 RPM. I can let it run at fast idle for a few minutes but as soon as I tap the gas to get it to stop fast idling the RPM’s drop and then the engine dies. After that I can’t get the engine to restart. I’ve been toying with the idea of replacing the gas tank (which I suspect is long overdue) along with a new fuel pump but I don’t know if that would have anything to do with this. I wouldn’t think so as it will start cold and fast idle for a good bit before it dies. Thanks as always for any ideas!

My '72 351C (2v) has an electric anti-diesel solenoid on the the accelerator linkage. If your idle is set too low and that solenoid is not connected (or working) it could let your idle drop too low. Check to see if you have that and if so it's working properly -- just my suggestion

 

[tcromwell35]

Hi everyone I wanted to say I appreciate the replies. Unfortunately I don't know enough about carburetors and haven't had time to read up / study so I think I found someone locally to help me troubleshoot it. While I am at it though I am planning on replacing the fuel tank. I looked at West Coast Classic Cougars but was wondering if anyone had a recommendation? Thanks again.