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302 pulsating
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302 pulsating
My '87 F-150 / 302 FI was runing fine until my alternator went out. Since replacing the alternator, the engine doesn't like to idle. It seems the problem is more apparent in warmer weather.
It starts fine, but it seeems like it is choked, and tries to die, but then it revs way up and persists in this pattern. Fuel consumption is a joke, and it smells like there is unburned fuel in the exhaust. It blows black smoke when first driven, but it clears up when the engine gets to operating temp.
Could this possibly be a faulty MAP sensor?... or something more sinister?
Thanks in advance...
It starts fine, but it seeems like it is choked, and tries to die, but then it revs way up and persists in this pattern. Fuel consumption is a joke, and it smells like there is unburned fuel in the exhaust. It blows black smoke when first driven, but it clears up when the engine gets to operating temp.
Could this possibly be a faulty MAP sensor?... or something more sinister?
Thanks in advance...
Last edited by vaskel; Jul 18, 2006 at 01:00 AM. Reason: spelling
More Turbo
Joined: Jun 2004
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From: Sweden
does it run ok? if it's only idle then it's likely the idle control valve
otherwise, throttle position sensor, MAP sensor, O2 sensor, coolant temp sensor, or major vac leak from cracked vac lines or the steel "coffee can" vac reservoir behind the battery.
Actually you are almost certainly the coolant temp sensor. There are 2. One is a switch for the computer, the other is just for the gauges. You need the computer one.
otherwise, throttle position sensor, MAP sensor, O2 sensor, coolant temp sensor, or major vac leak from cracked vac lines or the steel "coffee can" vac reservoir behind the battery.
Actually you are almost certainly the coolant temp sensor. There are 2. One is a switch for the computer, the other is just for the gauges. You need the computer one.
Last edited by Dannym; Jul 18, 2006 at 01:29 AM.
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Not really... it likes to intermittently try to die, even at highway speeds. It also does this when I use the cruise control.
ALl of my vacuum lines appear OK. It just seems odd that this problem 'appeared' after changing a major electrical compnonent.
ALl of my vacuum lines appear OK. It just seems odd that this problem 'appeared' after changing a major electrical compnonent.
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302 pulsating
Originally Posted by Dannym
There are connectors in that area that you might knock off.
Cross-Country
Joined: Oct 2005
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Start the engine, then disconnect the MAP while the engine is running, if the idle smooths out, the MAP is bad. The PCV is in the back of the upper intake manifold and connects to the passenger valve cover.
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Hotshot
Joined: Jul 2002
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From: Bend,OR
the pcv is on the back of the intake. check for codes www.fordfuelinjection.com will show you how and takes only a few mins. pull the vacum line from the fuelpressure regulator. if gas is present then its bad. also check your oil and smell the dipstick for fuel
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Originally Posted by Kemicalburns
the pcv is on the back of the intake. check for codes www.fordfuelinjection.com will show you how and takes only a few mins. pull the vacum line from the fuelpressure regulator. if gas is present then its bad. also check your oil and smell the dipstick for fuel
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