Questions and Answers

Chrysler Fifth Ave Bucking Q. I have a 1989 Chrysler Fifth Ave, 318 engine automatic transmission, 57,000 original miles, carburetor. The problem is the car bucks when ever you go out on the highway, Only after 60 mph. Never when on a load going up hill or coasting down and never when driving around town. I have replaced the fuel filter, fuel pump, wires, plugs and rotor. Nothing has helped. Where do I go next? Doreen

A. There can be several reasons for this problem Doreen. Most are easy to check and/or repair.

The things to check for outside of the carburetor is the air filter, make sure it is clean. Install a new one if you have doubts. There could be a vacuum leak. Check all the vacuum lines and make sure they are in good condition and that they are securely fitted.

Check the heated air intake system. Make sure the heat tube from the exhaust manifold is in good shape and connected firmly. Check the heat collector around the exhaust manifold and make sure it is in good condition and fastened properly. Also make sure the vacuum motor that opens the hot/cold flap in the air cleaner housing is working as it should.

The other possibilities are inside the carburetor itself. The gaskets inside may have deteriorated over time or the some of the internal passages may have clogged up. If this is the case, you will need to either rebuild or replace the carburetor. But before that, take it to a shop that has a four-gas emission analyzer and have the carburetor adjustment checked.