1993 Ford F-150 will not fire

Tiny
BILLYB71
  • MEMBER
  • 1993 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 102,000 MILES
Sometimes it will start run for awhile and stop again. After a few days it will start again.
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Monday, September 6th, 2010 AT 8:14 PM

2 Replies

Tiny
WRENCHTECH
  • EXPERT
All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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Monday, September 6th, 2010 AT 8:23 PM
Tiny
RASMATAZ
  • MEMBER
Next time it refuses to start don't wait for nothing hit it-do below to find out if its fuel or spark problem

Get a helper disconnect a sparkplug wire or 2 and ground it to the engine atleast 3/16 away from ground-have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, If you can hear the fuel pump come On- check the fuel pressure with a fuel pressure tester designed for your fuel system to rule out the fuel filter/fuel pick-up strainer/fuel pump/pressure regulator and also listen to the injector/s are they pulsing or hook up a noid light and see if it flashing, If you don't hear the fuel pump, check the fuel pump fuse and fuel pump relay-Depends on what type ignition system is yours, No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs, coil's resistances, distributor pick-up coil, ignition control module, camshaft and crankshaft position sensors and computer Note: If it doesn't apply to your vehicle disregard it meaning if it doesn't come with one ignore it and continue testing
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Monday, September 6th, 2010 AT 8:24 PM

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