Shedding Light on Headlamp Problem

Times Staff Writer

Question: My 1983 Nissan Sentra is fine with one exception. At night, my headlights do not project far enough ahead. They seem to project downward just in front of my car, and I have to rely on my high beams. Nissan told me that my lights conform to specifications, but I would like to know how far ahead they should project.--I.W.

Answer: Every state has a vehicle code that specifies how headlights must be aimed and where the headlights can be placed on the vehicle. These laws are complicated and performing the necessary adjustments to the letter of the law isn't easy for an automobile owner.

The code in California, for example, specifies that in a two-headlamp system, the intense portion of the light (whether on high or low beam) at a distance of 25 feet may not be higher than five inches below the lamp from which it comes. The code has similar restrictions on such things as stray light, high beams and fog lights.

So, if you want to be strictly legal, you should take your car to a garage specifically licensed to perform headlight adjustments. They use gauges that are calibrated to measure light beams in accordance with the vehicle code.

Many garages use a mark on the wall, which really isn't adequate. You could probably do just as well as that system by marking a spot on your garage door.

If the result is still that you find your headlights to be inadequate, you might consider adding fog lights. They must also conform to the vehicle code in their placement and aiming, but they would no doubt supplement your original equipment.

Q: I have a 1980 Toyota 4x4 pickup. The engine creates a vacuum block from time to time. When it occurs, I take the gas line off and turn on the engine until fuel runs through the line. It only takes a few minutes, and then I'm back on the road. Two different mechanics could not find a problem. Any comments would be appreciated.--K.A.

A: What may seem like a vapor lock may be simply a failure of the fuel pump to deliver adequate fuel to the carburetor. While not impossible, vapor locks are unusual in operating a vehicle in normal loads and temperatures.

You should first check to see that the fuel pump is producing the correct pressure. It should measure 4 to 4.5 pounds of pressure. If the pressure is inadequate, you could have a blockage in the tank screen or a malfunction in the pump itself.

Another possible cause you should consider is an improper fuel cap. The cap must allow air into the fuel tank but not permit fuel vapor to escape from the tank. If it is not permitting air in, a vacuum is created inside the tank as fuel is depleted. That would starve the engine of fuel.

If you have a vapor lock, you need to check that the fuel line is correctly positioned in running from the fuel tank to the pump. Make sure it doesn't pass too closely to the exhaust pipe or exhaust manifold. You also want to make sure that any shields or insulation are in place and functioning properly.

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