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Why engine does not fire?

Tiny
STOKES
  • MEMBER
  • 1999 FORD F-150
  • 205,000 MILES
Initially the vehicle began not to start. So I changed the crank sensor and there were no problems for approximately 3 wks. Then the problem began again. So I changed the crank sensor again with no results. I then pulled a spark wire, no fire going from the coil pack. Checked the connector leading into the coil pack again no fire.
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Saturday, April 28th, 2012 AT 1:52 PM

13 Replies

Tiny
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  • MECHANIC
  • 52,797 POSTS
Did youcheck for fuel pressure?

Roy
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Saturday, April 28th, 2012 AT 1:56 PM
Tiny
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Yes. There is little or no fuel pressure but there is no fire going to the fuel pump>>>There is just no fire. I have disconnected clean/sprayed the main harness on the firewall with no positive results.
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Saturday, April 28th, 2012 AT 5:15 PM
Tiny
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When you turn the key on, it will activate the pump for only 2 seconds. After that, it will turn on when the motor starts.

Check the interia switch behind the right lower kick panel especially if had it towed.

Roy
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Saturday, April 28th, 2012 AT 5:18 PM
Tiny
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Thanks>>>Have not been towed>>>But would the fuel pump being inoperable prevent getting fire at the coil and spark wires?
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Saturday, April 28th, 2012 AT 5:24 PM
Tiny
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Which motor do you have?

Did you crank it long enough with a good ground on the plug to check it?

Roy
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Saturday, April 28th, 2012 AT 5:27 PM
Tiny
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The vehicle has a 4.6 engine and yes to the length of cranks.
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Saturday, April 28th, 2012 AT 5:37 PM
Tiny
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It is rare for a no spark condition on the 4.6/5.4 series.

I would verify fuel pressure first with a gauge.

Roy
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Saturday, April 28th, 2012 AT 5:46 PM
Tiny
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But there is NO spark, so what else? Could it be the cam sensor?
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Saturday, April 28th, 2012 AT 10:04 PM
Tiny
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Yes, it could but it would throw a code if it was. Is there any codes? If not, I am still going to refer back to fuel pressure as it is the first check in a diag after compression test.

Roy
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Saturday, April 28th, 2012 AT 10:10 PM
Tiny
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Nothing is showing up on the codemachine. However I did put a live wire from a battery directly to the fuel pump wire leading to the fuel pump and did not hear the pump engage. If the pump is working would that generate fire/spark?
But my unlining question is why isnt there's fire from the coil and leading into the coil? Even if there is fuel would the vehicle start w/o spark? I am very thankful in your help>>>>Semper FI
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Saturday, April 28th, 2012 AT 10:21 PM
Tiny
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Hoo rah. Anyway, there should be a 12 volt feed to the coil. If there is not, then yes, there is a power issue to the coils.

If the pump did not fire up, then try spraying carb cleaner into the air filter and see if it comes to life for a few seconds. If it does, then you may have a pump issue. If not, then you have an issue with power to the primary ignition.

Roy
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Saturday, April 28th, 2012 AT 10:28 PM
Tiny
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Roy I am very thankful for all your effort in assisting me resolve the vehicle's problem.
With the help of my neighbor we did find out the problem. It was a fuse located in the Main (engine compartment)fuse box. He came over and hit the fues box cover and the vehicle started. I changed the fuse and all is working now. Semper FI
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Wednesday, May 2nd, 2012 AT 12:11 AM
Tiny
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Good, glad to hear it but I am concerned because fuses blow for a reason and if it is not found, it will do it again. Do not give up on this as I think you still have issues.

Hoo, rah

Roy
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Wednesday, May 2nd, 2012 AT 12:35 AM

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