Auto and Truck Repair and Advice
Serving the Gainesville and Hawthorne Florida Area
Auto Fuel Pumps
Your fuel pump supplies gasoline to run your engine. It gets the gas from the tank into your carburetor or fuel injection system.
There are two basic types of fuel pumps: mechanical and electric.
Mechanical pumps are mounted on the engine and are driven by the engine directly. (via an eccentric lobe on the camshaft)
Electric pumps are driven by the vehicle's battery and charging system (the alternator).
All modern fuel injected cars use electric fuel pumps, as well as some carburated cars. Many carburated cars use mechanical pumps.
ADVANTAGES AND DISADVANTAGES OF MECHANICAL FUEL PUMPS
ADVANTAGE: Mechanical pumps have been used for years and are less expensive than electric pumps. During a charging system failure, a car with a mechanical pump can drive for hundreds of miles, so long as the lights, A/C blower, wipers, etc. aren't used. The battery only has to fire the spark plugs.
DISADVANTAGE: When a mechanical pump fails, it can leak gas into your engine, thinning the oil and eventually destroying your engine. It can also leak externally and cause a fire.
CHECKING MECHANICAL PUMPS: Look at your pump every oil change (or have a qualified mechanic check it once a year at least). Look for gas or oil coming from the pump. When checking you oil, watch for a smell of gas. I "feel" my oil when I check it: I wipe the dipstick off with my finger and rub it against my thumb. You can tell if it gets thin way before it does any damage. By all means suspect the fuel pump if your oil level starts to rise above the full mark! Cars can't make oil, they only lose it. That extra volume is probably gasoline! Mechanical pumps can fail anytime after 50,000 miles.
ADVANTAGES AND DISADVANTAGES OF ELECTRIC FUEL PUMPS
ADVANTAGES: They can't leak gas into your engine. They are less likely to develop external leaks. The electric pumps are capable of developing the high pressures needed for fuel injection at all engine speeds and conditions.
DISADVANTAGES: They're usually more expensive than mechanical pumps and harder to replace. Many pumps are in the gas tank, making it a chore to get to them. Because they run off the battery/charging system, if the alternator stops charging you can't make it as far as if you had a mechanical pump. Vehicles with electric pumps often have larger alternators than non-electric pump vehicles.
CHECKING ELECTRIC FUEL PUMPS
Usually electric pumps work fine until they fail. Sometimes their normal "whirring" noise gets louder before they break. Sometimes they will stop when they heat up, and then start again when they cool off. If your car breaks down and you suspect the electric fuel pump, you can test it like this: Take the gas cap off. Have a helper turn the engine over while you listen at the gas filler. You should hear a "whirring" noise from the tank. (If the fuel pump is outside of tank, listen to it wherever it is. Most of them are in the tank, though.) Electric pumps also can fail anytime after 50,000 miles.
The Economechanix Cyber Mall
We also serve the surrounding communities of Alachua, High Springs, Hawthorne, and Newberry!
Thank you for visiting the ECONOMECHANIX WEB SITE. Please feel free to comment. We also serve the surrounding communities of Alachua, High Springs, Hawthorne, and Newberry! Gainesville has been my home since 1974, and I've loved Gvl and the Gators since I came here in the fall of 1974 to attend the University of Florida. I loved it so much I stayed and opened my car repair business. Originally it was out of the back of a 1963 Chevrolet wagon, but in 1977 a fellow mechanic and I opened an auto repair shop with actual walls, etc. I stayed in the same location for 26 years, and recently moved my operation to property I bought 15 miles east of Gainesville. I am doing most all the repairs myself now, having reduced my overhead from $1500 per month to practically nothing. I do work by appointment only. I mostly work only on my established customers cars, but I will occasionally take on new clients. E-mail me and I will either make arrangements to look at your car, or I will recommend you to someone who will.
George G. Scott, Jr.