i have a 1981 citation 4500 that has new points and condensers and coils but will not run right for a long period of time. If i put new plugs in it it will run fine for about 100 feet then one cylinder starts to backfire. if any one knows what could be casuing this please help. Thanx!!

I don't think it's the plugs,but when you pull them out what do they look like? you didn't say. you may have a fuel issue.do you have to pull many times before it starts.fuel pump may be very weak not keeping pressure up enough to keep floats full.your motor stalling sounds more like it is running out of fuel,or on the other hand fouling out because of a high float level or bad needle and seat,letting to much fuel thru.need more detail on plug condition so we can help you out. backfire when it has happened to my old 399 was a lean/no fuel problem.

Originally posted by rblscoot@Sep 11 2005, 10:59 AM
I don't think it's the plugs,but when you pull them out what do they look like? you didn't say. you may have a fuel issue.do you have to pull many times before it starts.fuel pump may be very weak not keeping pressure up enough to keep floats full.your motor stalling sounds more like it is running out of fuel,or on the other hand fouling out because of a high float level or bad needle and seat,letting to much fuel thru.need more detail on plug condition so we can help you out. backfire when it has happened to my old 399 was a lean/no fuel problem.
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If my memory serves me correctly the 4500 has a single carb so if there are any issue it should affect both cylinders. My guess would be a bad crank seal

Originally posted by Machster670@Sep 12 2005, 07:21 PM
If my memory serves me correctly the 4500 has a single carb so if there are any issue it should affect both cylinders. My guess would be a bad crank seal
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Actually, the Citation ss had dual carbs and the plain jane citation had a single carb. I had both.
I do agree, I think also that it is a crank seal(s). Easy to do, so do both.