1984 Corvette check engine light problem
Thread Starter
3rd Gear
Joined: Sep 2006
Posts: 3
Likes: 0
1984 Corvette check engine light problem
I own a 1984 Covette w/CFI the problem is the check engine light does not come on when the key is forward in the starting position. The vette will not start and the check engine light is good. Two months ago I replaced the the Control Module and the light worked and the vette started. I tinkered with the ACDL to pull any codes and the light went out. The fuel pump works but the injectors will not pump out fuel, I checked all fuses which are good and replaced the Control Module again and the vette will still not start. I put fuel in the carbs and the vette will start and once the fuel is gone the vehicle shuts off. I figured it might be the ECM but I don't want to spend that much on an ECM and that not be the problem and I am on a limited budget. Any help will be appreciated.
Pro
Joined: Dec 2002
Posts: 603
Likes: 0
From: 84 383 XFire Chandler, AZ
Have you tried hooking up a noid light to the injector(s) cranking it over and see if it lights up? When you state the fuel pump works how was this validated - fuel pressure gauge? You should also check the fuel pressure relay. It is located on the firewall on the passenger side about half way down. Sometimes the connectors will corrode and this may just be coincidental but I would not rule out the ECM. Also check the fuses.
How many miles?
How many miles?
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Now where is CFI-EFI when you need him? 
I don't comment on CFI to often because I'm not really familiar with the induction..but if it has the schrader valve on the fuel rail like a TPI you need to check fuel pressure. The noid light is also a good suggestion and easy to use, using it will tell you if the injectors are firing.
I don't comment on CFI to often because I'm not really familiar with the induction..but if it has the schrader valve on the fuel rail like a TPI you need to check fuel pressure. The noid light is also a good suggestion and easy to use, using it will tell you if the injectors are firing.
Instructor
Joined: Sep 2005
Posts: 173
Likes: 0
From: St. Louis MO
one way to test if its the ecm is to pull the chip out of it. If the check engine light comes on with the chip removed, then the chip itself may be faulty. (i will have to check my helms manual but i think it should give a code 43 if the eprom chip is missing.)
If you remove the chip, and the check engine light remains off, it is either a bad bulb or a bad ecm.
If you remove the chip, and the check engine light remains off, it is either a bad bulb or a bad ecm.
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Thread Starter
3rd Gear
Joined: Sep 2006
Posts: 3
Likes: 0
Checked the CFI with the noid light, has power but when cranked it does not flicker like it should, have not checked the fuel relay only because I think this would not cause the check engine light to not work. Fuel pressure is good and I can hear the fuel pump kick on when the key is turn forward to the start position. The vette did start two months ago when I changed the control module with this prior problem but I think I crossed two wires when I tried to pull codes from the ACDL which I think I shorted out the ECM. I changed all the fuses and rechecked everything all over a second time. Still confused on what it might be.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
no start
basic stuff here
the oil pressure swith in the back of the block is incase the fuel pump relay fails
If the fuel pump runs, but no start,
check to see that you have spark.
The engine will not spit fuel until the ECM senses engine rotation... check distributor connector behind the distributor and the tach wire and connector on the distributor cap.
also check to see that if you pour a tiny amount of fuel in the throttle body, it tries to fire. if it doesn't, maybe the ignition system from the key is bad, or a relay is bad
the oil pressure swith in the back of the block is incase the fuel pump relay fails
If the fuel pump runs, but no start,
check to see that you have spark.
The engine will not spit fuel until the ECM senses engine rotation... check distributor connector behind the distributor and the tach wire and connector on the distributor cap.
also check to see that if you pour a tiny amount of fuel in the throttle body, it tries to fire. if it doesn't, maybe the ignition system from the key is bad, or a relay is bad
Racer
Joined: Apr 2004
Posts: 380
Likes: 0
From: Farmington Hills MI
I get the impression that you do not drive this car very often. If so, I worry about fuel quality and/or a plugged fuel filter.
These problems are not always due to the complex items--sometimes the basic items can be the cause.
These problems are not always due to the complex items--sometimes the basic items can be the cause.
