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claymorgantowstrucks@yahoo.com
New User
Sep 17, 2014, 5:53 PM
Post #1 of 5
(2233 views)
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My 1991 Ford F150
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My 1991 Ford F-150 5.0 has lost spark won't start and I exhausted my self with my own knowledge on what the problem is.
I changed the coil and it still has no spark.
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Hammer Time
Ultimate Carjunky
/ Moderator
Sep 18, 2014, 2:15 AM
Post #2 of 5
(2209 views)
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Re: My 1991 Ford F150
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You need to check a few more things first.
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.
Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Sep 20, 2014, 11:45 AM
Post #3 of 5
(2165 views)
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Re: My 1991 Ford F150
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You know you have no spark at plug wire to ground?
Without wild tests and not sure you can the module on side of distributor can just go without warning, distributor pick-up coil but at the age a pest to change out. You may or may not see a problem inside distributor with cap removed and make sure the rotor turns when just cranking with cap off as a check too.
Outside is the relay with the brown skirt under hood not marked on it. Just whack it with plastic end of a screwdriver or like something and if it snaps to toss that one,
T
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Hammer Time
Ultimate Carjunky
/ Moderator
Sep 20, 2014, 12:12 PM
Post #4 of 5
(2160 views)
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Re: My 1991 Ford F150
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Yes, and you would just complete those tests, we may be able to tell you which of those things are likely without throwing out wild guesses.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Sep 21, 2014, 5:08 AM
Post #5 of 5
(2150 views)
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Re: My 1991 Ford F150
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I suggested looking at things and approaches wildly common for no spark for these. At some point with the age and predisposition of that generation of ignition if vehicle (other models too) a couple spares even without a problem makes sense like a spare tire.
Need more info now on how it was determined that it has no spark or fooled by testing? If a decent truck I'd be junk yarding for some spares and striking how many silly items are new and locally they don't even charge for that stuff,
T
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