There are four axioms to remember about troubleshooting:
A. The source of the problem is seldom where you think it is.
B. When all else fails, go back to the basics - simple solutions
often solve complex appearing problems
C. Just because a part is new doesn't mean it works.
D. Murphy's Law.
Never assume anything. Don't overlook the obvious. If the engine suddenly quits when running or refuses to start, check the easiest and most accessible spots first. Make sure there is fuel in the tank, the spark plugs are properly connected, check the connections on the distributor and on the coil for tightness. The most common problem is loose electrical connections because the vehicle has been subject to harsh or off road driving. You should be familiar enough with the engine compartment to know which wires go where. If a quick visual check of the obvious does not turn up the cause of the problem, look a little further.
Gather as many symptoms together as possible to aid in diagnosis. Learn to recognize and describe symptoms accurately and this will help you troubleshoot a lot faster. Saying "it won't run" isn't the same as saying " it quit at high speed and wouldn't start." Note whether the engine lost power gradually or all at once, what color smoke ( if any ) came from the exhaust and so on. Remember to more complicated engine symptoms become, the easier it is to troubleshoot them because symptoms point to a specific problem.
Below will be a list of problems. Click on the problem that you are
working on and this will take you to a list of possible outages. Please
be sure to follow each one step by step to correctly find the source of
the problem.
This troubleshooting guide is constantly being rewritten with the
learning's and feed back from you. Please provide input by e-mailing me
( Sierra Bronco ) with ways
you were able to find problems quicker or if there are other areas you
would like to see covered. I will try and cover all the basic areas of
a stock Bronco and also include some of the areas that we normally upgrade,
example: Electronic ignition, fuel injected motors, dual transfer case,
ect.
Through the troubleshooting guide there will also be links to wiring
diagrams, part breakdown diagrams, and general information pertaining to
the area we will be testing. These will be highlighted in blue to show
the links. Thanks in advance for using this troubleshooting guide and I
hope this helps you fix your bronco. Now go wheeling :)