Ford F-150 low idle?


Old 03-23-03, 03:29 AM
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Join Date: Dec 2001
Location: middleboro,ma
Posts: 279
Question Ford F-150 low idle?

I own a 1991 Ford F-150 with the 5.0L motor wich has 180,000
miles on it.Friday I had to have the altenator replaced wich had stopped charging.They also had to replace the belt tensioner unit,as they said it was too weak (original).
It charges fine now,but it seems it idles lower,with some tendency to stall when cold?
Could this extra new tension be putting slightly more load on the engine?
Is there a simple way I could adjust the idle up on this motor,what do you suggest?Thanks
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Old 03-23-03, 04:50 AM
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Join Date: Mar 2003
Location: Texas
Posts: 616
You might try adjusting the belt an make sure you have enough deflection in the belt, you should consult a manual for your truck but most of the time its between 5-10mm. If you need to adjust it there should be a few adjusting bolts on the mount. If itís injected there is no way to adjust the idle short of reprogramming the chip.
Old 03-23-03, 04:30 PM
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There is likely no adjustment on the belt---it's automatically tensioned.

The alternator is probably bad and not putting out enough. Pay the extra money and have them put in a Motorcraft rebuilt, it will deliver longer service.
Old 03-24-03, 05:03 AM
Oil Doc
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WeldGod is correct in that there is no real way to adjust the idle. But as in the cas with my 92 Ford with 305,000 miles, I was doing a tune up and the idle was down when I was done. It turned out to be a brittle, cracked vacuum line. When the vacuum lines were replaced, it ran fine. Worth checking and a lot cheaper than paying twice for an alternator.

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