83 Merc -need diagnost help
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83 Merc -need diagnost help
i have an 83 mercury grand marquis, 302 efi. runs great 73,000 miles resent tune up (oil,filters,plugs, wires, cap and rotor). but now she is tempermental. i can go out and she granks fine but won't start. it was cold and dark out this evening when i tried to get it running, didn't have any tools with me but could't get a spark to jump when i loosened the cool wire. i took the electronic control box off the fender to the local parts store and it checked out ok. also tried new coil, no change. 1 guy said it might have a crank sensor bad. if anyone might agree with that, could you tell me where it might be located? or any other sugestion?
i have been driving the car daily after the tune up with no problems, this just came up. i thought i narrowed it down to a 14 guage ground wire that goes directly to the battery. the last time she had 1 of these spells i check the wiring and found a bad splice. i fixed the splice and the car started. ran fine dove back and forth to work for 3 days and now she is dead again.
what do you think?
i have been driving the car daily after the tune up with no problems, this just came up. i thought i narrowed it down to a 14 guage ground wire that goes directly to the battery. the last time she had 1 of these spells i check the wiring and found a bad splice. i fixed the splice and the car started. ran fine dove back and forth to work for 3 days and now she is dead again.
what do you think?
Last edited by hb1506; Dec 1, 2004 at 09:55 PM. Reason: typo
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Do you have the dreaded TFI module?
And it's electric for sure, right? Can't be the timing chain all loose and sloppy giving you variable valve and ignition timing? (I'd check that out after you get the electric fixed, just for grins.)
And it's electric for sure, right? Can't be the timing chain all loose and sloppy giving you variable valve and ignition timing? (I'd check that out after you get the electric fixed, just for grins.)
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ii believe it's electrical, not sure though
have tried pouring a little gas in the throttle body, no change still didn't fire. i don't think i have timing gear problems because when it does run it's smooth and idle's fine.
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Joined: Jun 2002
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From: Atlanta GA
> 1 guy said it might have a crank sensor bad.
Some advice, you do not have one on your car. That year should use the hall effect switch inside your distributor to determine engine speed. If you have the box on the fender, you probably do not have a TFI module ($30) on your distributor. Which means you have a Duraspark II ignition?
The hall effect switch rarely goes bad, the pickup does. You could try replacing that. <$10. For most people, to replace the switch means replacing the distributor.
In this case, I would replace the module no matter what the tester said at the parts store. Then I would check the connector for the coil, since the coil is new. Remove it and test the front and back of the connector to see if it OHMs out or not. Many times the leads rust/rot out and will not pass power or ground to the coil. You can buy a new connector for less then $10 at Autozone and splice it in with butt connectors.
Some advice, you do not have one on your car. That year should use the hall effect switch inside your distributor to determine engine speed. If you have the box on the fender, you probably do not have a TFI module ($30) on your distributor. Which means you have a Duraspark II ignition?
The hall effect switch rarely goes bad, the pickup does. You could try replacing that. <$10. For most people, to replace the switch means replacing the distributor.
In this case, I would replace the module no matter what the tester said at the parts store. Then I would check the connector for the coil, since the coil is new. Remove it and test the front and back of the connector to see if it OHMs out or not. Many times the leads rust/rot out and will not pass power or ground to the coil. You can buy a new connector for less then $10 at Autozone and splice it in with butt connectors.
