cranks but wont turn over. check engine light was on and off...
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Junior Member
Joined: Jun 2006
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cranks but wont turn over. check engine light was on and off...
over the past few days my check engine light has been going on and off, i have an '89 f-150 with a 300 I-6 EFI. i couldnt immediatly figure out why the light was going on, so i figured there was some fuel contamination, usually saltwater moisture in the tank (happens frequently where i live with any vehicle), so i switched tanks. that solved the problem for a day or too. now its been going on and off every time i start the truck, and on my way home the truck died while idling, then it started with a lot of work (usually starts up without a question), and it died while in gear driving up a hill, and will crank but will NOT start. the fuel cutoff switch is not engaged, so thats not the problem, and i have no idea what else it could be. please please help, this truck is now blocking my driveway so no one else can get in or out.
Last edited by vlgrdsplyofpete; Jun 10, 2006 at 05:08 AM.
Senior Member
Joined: Oct 2002
Posts: 7,295
Likes: 125
From: St. Louis (Out in the woods)
Cranks but does not fire: Diagnostic steps
Cranks but does not fire:
Basic diagnostic procedure is to determine which of the three basic requirements is missing.
AIR - Crack the throttle while cranking. If it now fires, it's usually the IAC.
FUEL - Measure fuel pressure and verify in tolerance. Shortcut - spray starter fluid into the throttle body to see if it fires.
SPARK - Check for spark by pulling a plug wire, insert a screwrdiver into the boot, then laying the driver just off (1/16") a metal part of the engine. Crank engione and watch for a spark.
The CEL can be analyzed on your 89 with nothing more than a paperclip, some instructions, and some patience. See www.foredfuelinjection.com for instructions or maybe they're around here somewhere.
Once you have the codes AND you've determined which sub-system isn't working, it will be much easier to zero in on the source of the problem.
Steve
Basic diagnostic procedure is to determine which of the three basic requirements is missing.
AIR - Crack the throttle while cranking. If it now fires, it's usually the IAC.
FUEL - Measure fuel pressure and verify in tolerance. Shortcut - spray starter fluid into the throttle body to see if it fires.
SPARK - Check for spark by pulling a plug wire, insert a screwrdiver into the boot, then laying the driver just off (1/16") a metal part of the engine. Crank engione and watch for a spark.
The CEL can be analyzed on your 89 with nothing more than a paperclip, some instructions, and some patience. See www.foredfuelinjection.com for instructions or maybe they're around here somewhere.
Once you have the codes AND you've determined which sub-system isn't working, it will be much easier to zero in on the source of the problem.
Steve
Senior Member
Joined: May 2006
Posts: 268
Likes: 0
From: British Columbia
Checking spark
I thought that it was harmful to modern ignition systems to check spark in the manner you described, one elegant workaround I saw was a sparkplug mounted in a strip of metal with an alligator clip at one end, connect lead to test plug and away you go....been meaning to make one for myself for years.