'82 won't start...a little help please
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3rd Gear
Joined: Aug 2005
Posts: 3
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'82 won't start...a little help please
The fuel pump relay is not being activated. I believe it is controlled by the ECM, but is there any other sensors/relays that could cause this? If I momentarily manually activate the fuel pump relay, the engine starts and runs fine. 
Race Director
Joined: Dec 1999
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How do you know the relay isn't activating, did you check it (remove cap, turn ign. on and see if the contact moves)??? If so, not only the ECM controls the relay, the oil pressure sender is also a cut off switch for the relay (a safety feature so the car can't be started without oil pressure), check the big rubber connector next to the distributor.from your description it sounds like a problem w/ this oil pressure switch and the cranking oil pressure being too low to activate it yet while running (higher rpm) it's adequate for activating the relay.
Le Mans Master
Joined: Jul 2005
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From: Austin Texas
Originally Posted by Twin_Turbo
How do you know the relay isn't activating, did you check it (remove cap, turn ign. on and see if the contact moves)??? If so, not only the ECM controls the relay, the oil pressure sender is also a cut off switch for the relay (a safety feature so the car can't be started without oil pressure), check the big rubber connector next to the distributor.from your description it sounds like a problem w/ this oil pressure switch and the cranking oil pressure being too low to activate it yet while running (higher rpm) it's adequate for activating the relay.
Correction, I believe TT, The fuel pump relay is only activated during cranking, until the engine starts. Once the oil pressure switch closes (at about 7 psi). or the engine starts, all fuel pump power goes thru the oil pressure switch.....The fuel pump WILL run for 2 seconds after the ignition key is moved to the ON position.
Last edited by big_G; Aug 19, 2005 at 10:40 PM.
Race Director
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Yeah you're right, after cranking the switch takes over and supplies the 12V to the pump (the 12V ign switched coming off the ECM is split into 2, 1 to the switch and 1 to the relay, first the relay supplies 12V and then when the relay cuts off after the drive voltage from the ECM stops the 12V is supplied by the now closed pressure switch) I had a look at the schematics and that's how it was 
.... so it's the relay. Either the relay itself or the drive feed (can't be the ign switched source since that's the same for relay & switch), the drive voltage is the green/white wire.
.... so it's the relay. Either the relay itself or the drive feed (can't be the ign switched source since that's the same for relay & switch), the drive voltage is the green/white wire.
