I have a "91" F150 that Idles way to high it has a 5L EFI engine I've tried everything to get it down. Even unplugged the air vacuum sensor. If anybody can suggest something to help me out it would be greatly appreciated!

 

My '91 has the same snag. For me, unhooking the vacuum sensor worked, but that's only good in the warm weather.

Did you finally get it fixed?

PB

 

No I didn't get it fixed yet. :-(
What exactly did you unplug?

 

There is a way to adjust the idle speed a little bit, look on top of the throttle body for the adjustment screw. It won't let you adjust it down much, but it might help. Also try replacing you're Throttle postition sensor, or adjusting it. But to adjust it you'll have to remove the throttle body. I've got mine adjusted to where it just barely touches the cams on the sensor.


1988 F-150, SWB, 5.0 EFI (formerly 4.9 EFI), M5OD 5 speed, 3.08 gears, Summit shorty truck headers, Custom built Flowmaster exhaust system. Force 4 LP6000 lightbar, Federal signal PA-300 100 watt siren, Icom IC-V100 50 watt mobile radio.
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1965 F-100 (just purchased 1/18/01), SWB, 390, C-6 auto. Dual exhaust, Not much else to do to it.

Can see both below.

[link:www.geocities.com/hotrodford_88/|Hotrodford_88's Webpage]

 

I had the same problem on my 91 also on the 88 that I had previously, both trucks had the 5.0 engine. what was wrong with both of mine was the gasket between the upper and lower intake was blown out. I replaced the gasket and that took care of the problem. Also I would go with an aftermarket gasket like felpro as they are alot tougher than the factory ones. Hope this helps!

 

The fast idle governor can be disconnected. Just unplug it. It's on the front-right side of the carb intake, below the two humongous hoses. It completely solves the problem, although you will probably need to keep the revs up for 30-seconds or so when starting on cold mornings.

 

Ok Thank you I will try that!
Bill

 

I had tried unplugging the governer and the Idle did not change at all. And I replaced it too.

 

WELL THANKS FOR ALL THE HELP!! Oo IT WAS THE INTAKE MANIFOLD GASKET! GOT IT FIXED,WHAT A RELEIF!!SO THANK YOU ALL :-)
BILL