Questions and Answers

Surging Sunbird Q. Vince, I have a 1985 Pontiac Sunbird 1.8 liter with 150,000 miles whose engine started missing occasionally as well as surges when accelerated. I thought I had a tank of bad gas or foul distributor system but I replaced tank of gas, distributor cap, rotor, air filter, breather, etc. with no improvement.

Do you think it is a clogged gas filter or electric fuel pump going bad? Does an electric fuel pump behave sporadic?

Ellis

A. I would definitely replace the fuel filter if there is a question about it. It's cheap and easy to do. I would also put a new set of spark plugs in if they haven't been changed recently. Either one of these would cause the problem you describe.

It is also possible the fuel pump is going bad. A fuel pressure test will reveal any variation in pressure. Proper fuel pressure should be 9 to 13 psi at idle. The fuel pump should supply ½ pint or more within 15 seconds.

Another possibility is the carburetor itself. It is likely to have a lot of dirt and sediment inside it and, at this age and milage, can use a rebuild or replacement. A shop that has a four gas emission analyzer can check it to make sure it is adjusted properly.

One other thing to check is the O2 sensor. A bad O2 sensor is usually the cause of driveability problems like this as well.

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