1985 corvette fuel injector problem
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6th Gear
Joined: Oct 2015
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1985 corvette fuel injector problem
I have a 1985 Corvette that has problem with the fuel injector . It started when it wouldn't start and I smelled gas. I checked my oil dip stick and I had gas in the oil. I then removed all the spark plugs and found gas in all the cylinder. I replaced all the fuel injectors and I still have the problem. I pulled all the electrical connectors from the injector and found that I turn on the key I have 12 volts to all the injector causing them to spray gas into all the cylinder. The only thing I can think it is the ECM. What do you think
Safety Car
Joined: May 2001
Posts: 4,761
Likes: 1,648
From: Fairfax Virginia
Injector issues
Could it be something to do with the 9th injector (cold start injector) leaking or running too much? Try unplugging the harness connector to the 9th injector and see what happens. You might check its power while you are at it.
If it is not the injectors, and not the FPR the last place gas can come from is the cold start system, am I right?
I did have an injector go bad where it leaked down the fuel pressure in minutes. That particular injector (#6) tested out fine voltage wise and the noid light indicated that all was well. I just never got gasoline in the oil from a bad injector.
I wish you the very best in your pursuit!
If it is not the injectors, and not the FPR the last place gas can come from is the cold start system, am I right?
I did have an injector go bad where it leaked down the fuel pressure in minutes. That particular injector (#6) tested out fine voltage wise and the noid light indicated that all was well. I just never got gasoline in the oil from a bad injector.
I wish you the very best in your pursuit!
Last edited by ctmccloskey; Nov 11, 2016 at 04:12 PM. Reason: spelling error
Thread Starter
6th Gear
Joined: Oct 2015
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I have checked the cold start injector and it was great but the when you put a meter across the two leads on each injector I have 12 volts which is cause the injector to pump gas into the engine. The ECM is not suppose to be grounded causing the 12 volts.
Safety Car
Joined: May 2001
Posts: 4,761
Likes: 1,648
From: Fairfax Virginia
The way the injectors work
Hello again "Junkyard Dog"
What was said above by JimLentz sounds right. Most computers do not handle voltages and current inside them but instead when they want to make an item work, they "Pull to Ground".
Knowing this helps explain the operation of the injector. One side of the harness has a constant Battery + voltage (12 Vdc). Now when your computer wants to make the injector squirt fuel it supplies a GROUND signal (0 Vdc) which completes the circuit and makes the injector operate and release gasoline out of the nozzle. When the ECM wants to fire the injector it will supply the ground which complete the circuit.
The cold start injector is the one on the drivers side underneath the upper intake manifold. It too might have 12 volts to one terminal and the other would go to ground when the ECM tells it to inject the extra fuel needed for a cold start. This injector should only stay "on" for a short time if at all. It uses a temperature sensor on the engine to tell the ECM if the cold start injector is needed. The cold start injector is like the choke on your carburetor, once the engine is warm you do not need the cold start injector to start the engine. If the cold start injector is running all the time the engine would have way too much fuel, smell like gas and be very difficult to start. A good analogy would be like trying to start your car with the choke on when it was warmed up already, it usually floods the car with excess gas.
The cold start injector uses its own temperature sending unit that could be bad, the injector could have failed but whatever is going on in your car sounds a lot like this scenario to me. Find the cold start injector and unplug it. It has the same type harness as an injector has, by unplugging it you will stop it from receiving a signal to dump more fuel into your engine.
One last thing, I believe that by holding the pedal to the floor during cranking the computer is supposed to clear any flooding inside the engine during a start up. You might give that a try as well. Once running change that oil!
Good luck!
What was said above by JimLentz sounds right. Most computers do not handle voltages and current inside them but instead when they want to make an item work, they "Pull to Ground".
Knowing this helps explain the operation of the injector. One side of the harness has a constant Battery + voltage (12 Vdc). Now when your computer wants to make the injector squirt fuel it supplies a GROUND signal (0 Vdc) which completes the circuit and makes the injector operate and release gasoline out of the nozzle. When the ECM wants to fire the injector it will supply the ground which complete the circuit.
The cold start injector is the one on the drivers side underneath the upper intake manifold. It too might have 12 volts to one terminal and the other would go to ground when the ECM tells it to inject the extra fuel needed for a cold start. This injector should only stay "on" for a short time if at all. It uses a temperature sensor on the engine to tell the ECM if the cold start injector is needed. The cold start injector is like the choke on your carburetor, once the engine is warm you do not need the cold start injector to start the engine. If the cold start injector is running all the time the engine would have way too much fuel, smell like gas and be very difficult to start. A good analogy would be like trying to start your car with the choke on when it was warmed up already, it usually floods the car with excess gas.
The cold start injector uses its own temperature sending unit that could be bad, the injector could have failed but whatever is going on in your car sounds a lot like this scenario to me. Find the cold start injector and unplug it. It has the same type harness as an injector has, by unplugging it you will stop it from receiving a signal to dump more fuel into your engine.
One last thing, I believe that by holding the pedal to the floor during cranking the computer is supposed to clear any flooding inside the engine during a start up. You might give that a try as well. Once running change that oil!
Good luck!
Last edited by ctmccloskey; Nov 12, 2016 at 11:51 AM. Reason: Hit the wrong button.
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Thread Starter
6th Gear
Joined: Oct 2015
Posts: 6
Likes: 0
Hello again "Junkyard Dog"
What was said above by JimLentz sounds about right. Most computers do not handle voltages inside them but instead when they want to make an item work they "Pull to Ground".
Knowing this helps explain the operation of the injector. One side of the harness has a constant Battery + voltage (12 Vdc). Now when your computer wants to make the injector work it supplies a GROUND
What was said above by JimLentz sounds about right. Most computers do not handle voltages inside them but instead when they want to make an item work they "Pull to Ground".
Knowing this helps explain the operation of the injector. One side of the harness has a constant Battery + voltage (12 Vdc). Now when your computer wants to make the injector work it supplies a GROUND