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1998 Ford F-150 At wits end

Tiny
CMPICKER
  • MEMBER
  • 1998 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 120,000 MILES
I am by no means a mechanic and I have a problem that none of my friends or I can fix. I recently bought a 98 f150 4x4. It ran great for about 3 weeks and then just quit on my wife one day about a month ago and hasn't ran since. I have a 2nd 1998 f150 that runs great so I have traded out several items and bought new, several items. There is no fire at the spark plugs. We tried changing coil packs, crankshaft position sensor (new), cam shaft position sensor (new), we've traded out the whole air intake system, we rented a scanner from autozone and all it said was what we knew, no fire to the plugs. I checked all the fuses and swapped around all the relays in the distribution boxes on the driver side under hood. I checked to make sure the fuel cut off switch in the passenger foot panel was pushed (although I know this has nothing to do with fire to the plugs). I am at my wits end and can't afford to take it to a shop. Any ideas would be appreciated.
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Friday, June 11th, 2010 AT 11:36 AM

10 Replies

Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Have you checked to see if the ECM is sending power to the coils? If not that will need to be checked it may be that you have a bad ECM. If you have a digital multi meter we do a couple of tests.
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Saturday, June 12th, 2010 AT 9:23 AM
Tiny
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As I said in my message, I am not a mechanic, so, I don't know what the ECM is. I do have a digital multi-meter.
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Saturday, June 12th, 2010 AT 11:00 AM
Tiny
RACEFAN966
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Ok I understand that you aren't a mechanic not everyone is or can be. I do need to know how comfortable you are with running some tests if I walk you through them. The ECM is the Computer for the truck. How did you determine that there is no spark? Have you check the fuel pressure? Get back to me with what you can so we can try to figure this out ok.
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Tuesday, June 15th, 2010 AT 10:05 AM
Tiny
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  • 5 POSTS
I determined no fire at plug by removing the spark plug wire, inserting a conductive metal rod (a screwdriver) into the plug wire touching the metal contact deep in the socket, then holding the rod very close to a metallic part of the engine. I saw no fire jump from the rod to the ground of the engine, while turning over the engine. I then did the same thing using my digital multimeter, placing the positive probe in the wire socket and the negative probe on ground and saw no voltage reading in the AC or DC mode, while turning over the motor. I do not know how to check for fuel pressure, but I assumed a fuel delivery problem would take 2nd place to no fire. I did determine that the fuel pump was running by placing a funnel into the gas port and putting my ear to the funnel, when the key was turned on, I could hear the fuel pump engage.
Thanks for your response, and please excuse the delay in my reply, I work 10.5 hrs a day 6 days a week, presently.
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Friday, June 18th, 2010 AT 10:58 AM
Tiny
RACEFAN966
  • MECHANIC
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Ok I hear you there is no spark. Now before I go to the next test I need some info. When you had the scan tool did it give any codes and if so what were they? I would also like you to check a couple of wires with you meter, set it on ohms and ohm a couple and let me know what the ohms are, I need to know what engine you have the 4.6ltr or 5.4 ltr.
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Saturday, June 19th, 2010 AT 9:11 AM
Tiny
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I checked one wire on each side and found 40 to 50 ohms
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Saturday, June 26th, 2010 AT 1:36 PM
Tiny
RACEFAN966
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Ok great that looks good. Now I still need to know which engine you have 4.6 or 5.4ltr.
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Tuesday, June 29th, 2010 AT 10:51 AM
Tiny
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It has a 4.6L engine
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Wednesday, June 30th, 2010 AT 11:06 AM
Tiny
RACEFAN966
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Ok what I need you to do is pull a spark plug wire off a spark plug and put a philips screw driver it the end of the wire and place it near metal (valve cover) and then crank it over do you see spark and if so what color is it. Lets start hear and then we will test the coil pack, cam and crank sensors ok.
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Thursday, July 1st, 2010 AT 11:06 AM
Tiny
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I have already performed this test. There is no spark at all. I also have another working 98 ford f-150 with a 4.6L motor (not 4x4). I swapped both coil packs out on the trucks. After swapping the packs, the 4x4 still wouldn't run and the other truck started right up with the 4x4 coil packs on it.
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Thursday, July 1st, 2010 AT 4:21 PM

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