Diagnosing Faulty Fuel Pumps

For older models, it wasn't hard to detect when yourfor whatever reason, it was actually the wiring that
fuel pump was going out, and it was almost as easyfailed, not the pump itself. The only way you could
to replace. There were two spots where you cantell that something was amiss, other than you
find the fuel pump, either somewhere near thecouldn't get your vehicle started, was that electrical
underside of the block, or attached to the head, nearfuel pumps could be heard working. You could actually
the camshaft. How these pumps work is that thehear it whirring, if it was working.
pump unit consisting of a one-way valve, and aInstead of having to pull the whole fuel tank off to
diaphragm that moved up and down with a pumpget at the pump, you can pick up inline pumps, that
handle, mounted inside the block, resting against atotally by-pass the main pump, and is placed along
part of the crankshaft. When the crankshaft turns, itthe firewall in the engine compartment. You connect
makes the pump handle move up and down, pumpingthe fuel lines, and connect it to a power source. If
fuel from the tank to the carburetor.you don't know how to tie it all into your wiring
These car parts weren't very hard to replace, andsystem, so it only came on when the motor was
the main thing that usually went wrong was eitherstarted, you could put a kill switch, somewhere either
the handle mechanism, or the internal diaphragm. Youclose to the battery or mounted somewhere in the
could tell right away, loss of fuel to the motor, thedash. Newer vehicles with fuel injection have a slightly
heavy smell of gasoline, and you could actually seedifferent fuel delivery system. Fuel comes out from
gas spewing out from the little breather hole. Thethe tank, through the pump and filter, up to the fuel
whole unit can be removed with some open-endinjector rail, then into a fuel pressure regulator and
wrenches, and disconnecting the fuel lines. In frontback into the tank. These systems are more
wheel drive vehicles, the manual fuel pump would becomplicated than the older car parts, and you have
located by the camshaft, and the movement of themuch more to deal with diagnostic wise.
camshaft would make the pump work. You could findFirst thing you should do when trying to locate the
car parts to replace the pump at your local junk yard,fuel problem is turn off the vehicles motor, then turn
as well as order them brand new. You should alwaysthe key forward, If you can hear a whirring sound or
replace things like fuel and oil pumps, or alternators,an electrical motor sound, chances are your pump is
brand new, or refurbished in some cases, never fromfine. Next you need to check your fuel filter, located
a junk yard.either near the tank itself, or somewhere along the
Now when electric fuel pumps came out, there wereline near the motor. The filter will usually be made
ups and downs to them. One the high side, fuelfrom a hard clear plastic, and if you can see the little
pumps were now fully internal, and had now outsidefilter inside, it needs to be replaced. If this is all right,
components, other than the fuel lines, and thethen you would continue along the line, to the fuel rail
electrical connections. You never had to worry aboutand see if you have problems there, or with the fuel
the diaphragm going out, or the rod arm breaking.pressure regulator. If you still can't find the problem,
The problem was, for some stupid reason, someoneit may be best to have a mechanic look into it.
thought it was a better idea to put the pump unit inIf you need an inline fuel pump, fuel filter, or anything
the tank, and the idea probably was that now thatelse, you should first go to your local car parts
the pump was electric, it could be placed as close toretailer. With the computers they have, they can
the source as possible.usually find the parts you need, even if it is an older
The flip side was that the only way to tell that itmodel vehicle.
was going out was when it actually failed. Sometimes,