|
Engines
|
Troubleshooting
There are many simple tests you can perform if your engine is
not running. Let's start with the fuel system. Is the shut-off on
 the
tank open?
Is there fuel in the sediment bowl, if so equipped? If
you have downdraft carburetors, remove the flame arrestor and manually
pump the throttle. There should be a small stream of fuel. The fuel pump
can be tested with a pressure gauge. Before cranking over the engine,
remove the coil wire so the engine will not start. Most pumps should
hold 3 to 6 pounds with the engine cranking. If no gauge is available
you can loosen the fuel line from the carburetor, place a small can
under the line, and crank the engine. Use caution so as not to spill
fuel and clean up any leakage immediately. Any fuel filters should be
checked and either cleaned or replaced. If you find there is no fuel,
you must determine the cause and repair as needed.
If your fuel system is in proper working order, move on to the ignition
system. Again, there are many different systems. All pre-1975 engines
came with a "points-style" ignition system. Most later engines have some
type of electronic ignition system. Also, there are many early points
systems out there that have been converted to an electronic system. All
of these systems have a few things in common: they all require voltage
to work and they all have a coil, cap, rotor, spark plugs, and wires.
Lets start with a simple voltage test. Using a test light or voltmeter,
turn the ignition key, and check for voltage on the positive side of the
coil. It should test close to the battery voltage. If there is no
voltage on the coil, you will need to determine the cause. It could be
the ignition switch, a broken wire, or loose connector, among other
things.
If there is voltage on the positive side move your tester to the
negative side and crank the engine. The voltage should
 pulsate,
causing the test light to flash on and off. If there is no voltage pulse
at all on the negative side, there is a problem with either the points
or the electronic ignition trigger. If you have points, remove the
distributor cap and rotor and visually inspect the points. They should
be clean and dry. If they are pitted, blue in color, rusted, or oily,
replace them and the condenser. If you have electronic ignition, one
test works most of the time. Remove the coil wire from the cap and hold
it about 1/4 inch from a ground, then turn the ignition switch on and
off. If there is a spark when you turn the key on and off, The
electronic trigger is probably bad and must be replaced.
 If
you have the proper voltage on the coil, then check the condition of the
cap, rotor, and wires. The cap should be clean and dry. The contacts on
the rotor and cap should be free of corrosion and burning. Inspect the
cap for cracks. The cap should also be checked for corrosion where the
plug wires connect. If there are any of these signs, replace the parts
as needed. If all of these tests are ok and the cap rotor, wires, and
points look good, you have a bad coil. Coils can be tested with an
ohmmeter, but the specs might vary with manufacturer and type. If you
need it tested, bring it to any good automotive garage or just replace
it.
If there is a cranking problem with your engine, the first place to
start is with the battery. Is it fully charged? Just because a battery
shows voltage doesn't mean it has cranking power. Test your battery with
a hydrometer. All cells should read close to the same. A fully
charged battery will read 10275 specific gravity. Check the battery
connections for corrosion and looseness. If corroded, remove the cables
and clean them properly. There are specific tools for cleaning your
battery posts and cables, available at most auto parts stores. Also
check, clean, and tighten the cable connections at the starter and
ground connection on the block.
If your battery doesn't stay charged, then there possibly is a problem
with your charging system. Most earlier engine styles have a generator,
while later styles have an alternator. Either is fine, but an alternator
charges faster and also at slower rpm. If you have a 6-volt system, your
charging system should put out 7 to 8 volts at the battery at about 2,00
engine rpm. If you have a 12-volt system there should be 13.5 to 14.2
volts at the battery at the same rpm. If you have any doubts about your
charging system, find a good repair facility with the proper test
equipment. |
|
