95 F150 sometimes starts sometimes not

Discussion in 'Mechanic and Repair' started by KERRTURF, Nov 16, 2006.

  1. KERRTURF

    KERRTURF LawnSite Member
    Posts: 129

    I have a '95 F150 4x4 5.0 gas that starts most of the time, but not all of the time. I have pulled the ignition module and had it tested, and it is good. I don't have anybody to help me check if there is spark when it doesn't start so I'm not sure ( but I figure it is ) spark related. It has duel tanks and I have tried switching the tanks to see if it is a fuel pump issue but it doesn't make a difference. Also, it doesn't seem to make a difference if it is damp outside or dry, cold or hot, it is simply intermittent. Anybody have any suggestions?
     
  2. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    just a guess - if they haven't been replaced yet. distributor cap,rotor and plug wires.
    not too much info to go on.
     
  3. KERRTURF

    KERRTURF LawnSite Member
    Posts: 129

    I looked at the wires during the night, and there is no sign of leakage. The cap and rotor look good (no cracks, and not burned) I didn't pull the plugs. The thing is, when it runs it runs great. That is what is making me think it is a spark issue. I'm thinking maybe the coil, but I have never had a coil go bad sometimes. I've always thought that the coil either worked or didn't. Sort of like being pregnant, you either are or you aren't.
     
  4. Total.Lawn.Care

    Total.Lawn.Care LawnSite Senior Member
    Posts: 841

    I have a '94 F-150 with 5.0 and I had the same problem. Had an issue twice with it running fine, then just now wanting to re-start. I too had the ignition checked and I changed out the electronic module, distributor cap, rotor, wires, etc. Turned out when it left my wife completely stranded at school one afternoon, that the ignition was bad all along. Sometimes it till test okay, other times, it just will not work.

    BTW, I have 268,000 miles on that truck and we changed the ignition at about 258,000.
     
  5. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    If you have the ignition module that separate from the distributor then I can give you a test to try. When I was working on cars in the 70 and 80's the module might test good but still be bad. This will sound crazy but give it a try. Take the coil wire out of the cap and position the end real close to any metal or ground. 1/16 to 1/8 inch close. Then turn the ingition to the run position. Take a plastic hammer or piece of wood and tap the module fast and pretty hard but not hard enough to break it. If you even see one spark at the coil wire then change out the module. There may be a spark everytime you cycle the ignition switch on and off but this is normal.
    PS. The cap,rotor,wires and plugs can look good but be faulty. You can't always rely on seeing leakage from the wires in the dark. If they haven't been replaced in 11 years it would be money well spent anyway to replace them.
     
  6. KERRTURF

    KERRTURF LawnSite Member
    Posts: 129

    I will try to check the module with the tap method. I originally though it was the module anyway. I have already purchased another module, but after the original tested okay I out the original back in and kept the new one for a spare. Thanks for all of the help guys. Anybody else?
     
  7. KERRTURF

    KERRTURF LawnSite Member
    Posts: 129

    Okay, so I tried to start it again this afternoon and it would not start. Just cranked away. I put the new ignition module on it, and it still wouldn't start. Went down and bought a new coil and installed it, still no luck. Took the distributor cap off, and sprayed it with WD40 in case it was wet. Still no luck. I suppose I am going to go ahead and buy new wires, cap and rotor, and 8 new plugs to see if that will fix it. At least now I have a spare ignition module, coil, and that special wrench that I had to buy to get the **** module off of the heat sink. Watch out for my future posting that will indicate a good condition '95 F150 for sale with lots of new parts! Thanks for all of the info. I really do appreciate it, and if anybody has any other suggestions please send them my way.
     
  8. xcopterdoc

    xcopterdoc LawnSite Senior Member
    Posts: 752

    You have to find out a couple things. You need to know for sure its spark related or fuel related.
    Check for spark, you have to know yes or no.
    Fuel... listen for the pump to run for 2-3 seconds with key on, engine off.
    Signal to injectors, controlled by the PCM. (Powertrain Control Module) If you have a digital meter I can walk you thru most of the checks.
    A no spark could be a bad crank sensor, not always ignition related. And sometimes they work, sometimes they get pissy.
     
  9. KERRTURF

    KERRTURF LawnSite Member
    Posts: 129

    I haven't been able to check for spark since I don't have anybody to help crank the engine while I am under the hood. I will recruit a neighbor to help this weekend. I have checked for fuel by listening for the pump to kick on. It does kick on on both tanks. I didn't know I could check the PCM. I have a digital meter, and would love to hear how it is done. How hard is it to replace a crank sensor, and where is it located? Somebody else I talked to said there is a light that plugs into the coil that you can see if you are getting spark while you are in the truck, I have to find that! Thanks again.
     
  10. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    It's called an in-line spark tester about 10 to 15$. Check your parts store. You don't need a helper to check the module like I explained before. This is an accual Ford test. It works.
     

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