F-150 Starting Problem

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  #1  
Old 02-23-05, 05:48 PM
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F-150 Starting Problem

I have a 1990 FR-150 (302) that has a starting problem. It seems that once the engine gets up to temperature and is shut off, the engine will not turn over. It make a very weak attempt at doing so but it just does not seem to have the power to do so. I checked the alternator, battery, starter and coil and all seem to check out fine. Could this be an ignition control module problem or is there something I am missing? One other thing I have found is when the truck doesnot start if it is allowed to cool it will sometimes start. Can anyone help?
 
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  #2  
Old 02-24-05, 01:07 AM
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If the motor wont spin you need to concentrate your efforts on the parts that are involved. Over advanced timing will have it's own particular symptoms....

In your case, with the weak attempt at turning over, I would first think starter but I would like to prove it to myself before replacing parts. I would recreate the conditions needed to reproduce the problem and then perform a few simple voltage drop tests....

As with any repair, it is important to recreate the failure conditions when testing the system. If the concern is related to temperature, we need to test the related components when they are at the failure temperature.
HTH.
 
  #3  
Old 03-06-05, 11:05 PM
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Ok i have done this

Originally Posted by mechanic
If the motor wont spin you need to concentrate your efforts on the parts that are involved. Over advanced timing will have it's own particular symptoms....

In your case, with the weak attempt at turning over, I would first think starter but I would like to prove it to myself before replacing parts. I would recreate the conditions needed to reproduce the problem and then perform a few simple voltage drop tests....

As with any repair, it is important to recreate the failure conditions when testing the system. If the concern is related to temperature, we need to test the related components when they are at the failure temperature.
HTH.
Ok I tried to conduct a voltage droptest as per the Haynes manual specs. for the most part it cheked out with some unfavourable variances from relay to battery. The weirdest thing was that I received a 12 volt reading when I hooked up my negative lead of my voltmeter to the positive terminal of the starter and the positive lead of the voltmeter positive battery post. This reading occured even when the igntion switch was not tripped. Does this indicate a short somewhere in the stater or in the cable from starter to relay???
 
  #4  
Old 03-06-05, 11:17 PM
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If yours is a single terminal starter, this would be a normal reading. If you can get use of an inductive ammeter, I would compare cold strter draw to hot starter draw. Could be that the starter is "dragging" when warm.
 
  #5  
Old 03-06-05, 11:23 PM
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you only take voltage drop test readings while the engine is cranking over the starter is grounded when it is not turning over so 12 volts is a normal reading.
do each cable seperatly like battery to solenoid, solenoid post to post, solenoid to starter, negative battery post to block to check ground cable
could also check your base ignition timing you didnt state any running problems but it could be way to fast causing the starter to pull alot of amps on a warm start.
if everything else checks ok suggest you try a new starter as they may test fine cold but may drag when hot.
 
  #6  
Old 03-08-05, 05:53 AM
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try and hook up a second ground from the battery to the starter jumper cables work great if it turns over better than clean and check your grounds
if not than take the starter to your locak rebuilder and have them test it most will do it for free
 
  #7  
Old 03-10-05, 02:20 PM
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Now that you mention it, the truck is very hard to keep running for the first 10 mins after a cold weather start it hunt alot then quits if you dont hold the gas pedal down until the temp starts rising. Is this indicative of a timing problem??


Originally Posted by bejay
you only take voltage drop test readings while the engine is cranking over the starter is grounded when it is not turning over so 12 volts is a normal reading.
do each cable seperatly like battery to solenoid, solenoid post to post, solenoid to starter, negative battery post to block to check ground cable
could also check your base ignition timing you didnt state any running problems but it could be way to fast causing the starter to pull alot of amps on a warm start.
if everything else checks ok suggest you try a new starter as they may test fine cold but may drag when hot.
 
  #8  
Old 03-11-05, 02:39 AM
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no thats not a problem related to timing it probably just needs the throttle plates and idle air bypass cleaned for the problem you describe.
if timing was over advanced the engine would ping or spark knock on acceleration.
 
  #9  
Old 03-11-05, 05:44 AM
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could also be a bad cts (coolent temp sensor for computer ) but first try cleaning air intake
 
  #10  
Old 04-04-05, 04:05 PM
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Well I did the Voltage drop. I set my multi to 2 volt as per instructed in haynes. From battery to relay I get .6. From realy to starter I get .3-.5. From Negative post to ground I get .09. I took the starter to a rebuilder and they claim its testing fine. I even in a crunch situation tried a 1000cca 12 volt battery but even that would not turn it over (which I know is bad but the dar thing don't work anyway!). Could I be dealing with a partially seized engine???


Originally Posted by mechanic
If the motor wont spin you need to concentrate your efforts on the parts that are involved. Over advanced timing will have it's own particular symptoms....

In your case, with the weak attempt at turning over, I would first think starter but I would like to prove it to myself before replacing parts. I would recreate the conditions needed to reproduce the problem and then perform a few simple voltage drop tests....

As with any repair, it is important to recreate the failure conditions when testing the system. If the concern is related to temperature, we need to test the related components when they are at the failure temperature.
HTH.
 
  #11  
Old 04-05-05, 02:47 AM
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you should replace the 2 positive cables did you do a voltage drop on the solenoid mounted to the fender?
if not you test it the same way place each lead of the voltmeter to the 2 large post on the solenoid while the vehicle is cranking over you shouldnt have a reading above .3 on any of the cables or the solenoid.
the problem with testing the starter by removing it and taking it to a shop to be tested is that its not hot if your problem only occurs when the engine is up to operating temperature then the starter will check fine when its off the vehicle and cool.
 
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