Injector Voltage ??
Drifting
Joined: Dec 2002
Posts: 1,861
Likes: 4
From: Houston TX
Re: Injector Voltage ?? (LSC SS)
You don't check it for voltage, because it's the ECM closing an internal switch that completes the circuit to the injector. You need to check it with a test light. If memory serves, if the test light stays on all the time, or it never comes on, then you have a problem. If it periodically flickers while turning the motor over, then you're ok.
[Modified by CorvetteZ51Racer, 6:40 PM 4/3/2004]
[Modified by CorvetteZ51Racer, 6:40 PM 4/3/2004]
Thread Starter
Intermediate
Joined: Mar 2004
Posts: 29
Likes: 0
From: Spring Hill Florida
Re: Injector Voltage ?? (CorvetteZ51Racer)
OK, with the key on I have power at the pink/black wire, while cranking the light dims some (more than likely just voltage drop) but stays constant. The way I figure it I should have a ground signal from the other wire going to the ECM but am getting no such signal.
Maybe a little background on the car, this thing has been sitting for over 2 years, I put a new pump and sender in due to varnish corrosion, blew the whole system out and am now getting fresh fuel up to the rail. Plugs are 100% dry so I know the injectors are not opening at all.
The car will run if I put gas in a spray bottle and spray it into the intake.
I am getting over 40 lbs of oil pressure at cranking so if it has a low oil pressure cutout that should not be an issue.
Maybe a little background on the car, this thing has been sitting for over 2 years, I put a new pump and sender in due to varnish corrosion, blew the whole system out and am now getting fresh fuel up to the rail. Plugs are 100% dry so I know the injectors are not opening at all.
The car will run if I put gas in a spray bottle and spray it into the intake.
I am getting over 40 lbs of oil pressure at cranking so if it has a low oil pressure cutout that should not be an issue.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: Injector Voltage ?? (LSC SS)
The injectors are a solenoid operated valve. One wire of the coil goes to 12v and the other coil wire goes to the ECM which pulses to ground to energize the coil for short durations according to the throttle setting etc. To test the ECM, unplug an injector and connect a low power 12v lamp across the injector socket and crank the engine. You should see the lamp being pulsed. If no pulsing, then first check both injector fuses and then check for pulses on the purple/white wire from the distributor. The ECM pulses the injectors when it receives distributor pulse references . No pulses, no injector operation. Also, put a fuel pressure gauge on the shrader valve on the end of the fuel rail to determine if you have fuel pressure.
[Modified by jfb, 6:25 PM 4/3/2004]
[Modified by jfb, 6:25 PM 4/3/2004]
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Injector Voltage ?? (LSC SS)
The ECM bank fires the injectors so it has two drivers that ground each bank of injectors for a few mS at a time.
If you check one injector on each bank with that test light you know if the ECM is firing each bank.
Since you had varnish in the fuel tank I suspect you may also have some in the fuel injectors and maybe even the regulator.
If your check verifies that the ECM is firing both banks, you could pull the regulator and clean it. If that doesn't do the trick, pull the injectors and send the set to Rich at Cruzinperformance to be reconditioned. He does a set for around $100 or so with 48hr shop time. He even sends you the flow data when they are returned to you.
If you check one injector on each bank with that test light you know if the ECM is firing each bank.
Since you had varnish in the fuel tank I suspect you may also have some in the fuel injectors and maybe even the regulator.
If your check verifies that the ECM is firing both banks, you could pull the regulator and clean it. If that doesn't do the trick, pull the injectors and send the set to Rich at Cruzinperformance to be reconditioned. He does a set for around $100 or so with 48hr shop time. He even sends you the flow data when they are returned to you.
Thread Starter
Intermediate
Joined: Mar 2004
Posts: 29
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From: Spring Hill Florida
Re: Injector Voltage ?? (jfb)
Thanx to everyone for the great info !!
Here's where I'm at.
I have 40 psi at the rail with the key on and also when cranking.
I have no voltage across the injector connector with the key on or while cranking but do have voltage to the injector at all times. Guess my next step is to see whats what inside the distributor.
Here's where I'm at.
I have 40 psi at the rail with the key on and also when cranking.
I have no voltage across the injector connector with the key on or while cranking but do have voltage to the injector at all times. Guess my next step is to see whats what inside the distributor.
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Thread Starter
Intermediate
Joined: Mar 2004
Posts: 29
Likes: 0
From: Spring Hill Florida
Re: Injector Voltage ?? (LSC SS)
Another thought just occured. The car will run when I spray fuel down the intake tube so wouldn't that indicate that everything in the distrubutor is working well ??
Intermediate
Joined: Aug 2002
Posts: 37
Likes: 0
From: Houston TX
Re: Injector Voltage ?? (LSC SS)
I bet the injectors are clogged up. I am pretty sure the 1989s had 9 injectors, there is an extra cold start injector in the fuel rail. Maybe if that one is clogged it really hurts startup? (doubt it)
Hey if you're sellin this car, tell me what its reserve is. :thumbs:
[Modified by gatorback, 11:15 PM 4/4/2004]
Hey if you're sellin this car, tell me what its reserve is. :thumbs:
[Modified by gatorback, 11:15 PM 4/4/2004]
Thread Starter
Intermediate
Joined: Mar 2004
Posts: 29
Likes: 0
From: Spring Hill Florida
Re: Injector Voltage ?? (gatorback)
Sorry, cars not for sale, I'm fixing it for a friend. The injectors may well be clogged but I'm not sure if that would cause the electronic signal not to be completed
Team Owner
Joined: Jan 2003
Posts: 20,293
Likes: 240
From: Summerland B.C. Canada
Re: Injector Voltage ?? (LSC SS)
I believe the injector is always hot and ecm supplies ground to fire injector.
Check the ground side
:cheers:
Edit...Old news :smash:
[Modified by AGENT 86, 7:37 PM 4/4/2004]
Check the ground side
:cheers:
Edit...Old news :smash:
[Modified by AGENT 86, 7:37 PM 4/4/2004]
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
Re: Injector Voltage ?? (LSC SS)
LSC: Look into the fuse panel in front of the passenger door. There is a fuse for each bank of injectors...make sure they are good. Check the resistance of each injector (should be about 16 ohms). Otherwise, get ready to pull out the injectors. The 89 model has GM Multecs which are crap anyway! These tend to short out and will not fire! Have you changed out injectors before? It can be a pain if you pull the valve covers and runners. It can be done without pulling the runners! SAM
Thread Starter
Intermediate
Joined: Mar 2004
Posts: 29
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From: Spring Hill Florida
Re: Injector Voltage ?? (Sam Lam)
I checked the fuses and they are good, I bought a noid light set today and when I crank the car over the noid light does kind of like a strobe thing so I will assume that it is getting the proper signal (I have never used of these lights before so I hope I'm reading it right) and the problem is that the injectors are clogged.
Drifting
Joined: Mar 1999
Posts: 1,931
Likes: 1
From: Norcross GA
Re: Injector Voltage ?? (LSC SS)
This will help narrow it down to a clooged injector problem or and electronics problem.
After the pump primes the rail,... (Key in On position) watch the fuel pressure as you ground the ECM side of the injector. The fuel pressure should drop to nothing,... if some or all the injectors are passing fuel. You only need to ground one injector per bank to get the whole bank to open. (If you ground the wrong inj wire,.. you blow the bank fuse.) Grounding the ECM side if the inj while the engine is not running won't harm anything.
After you have primed and tested both banks for a pressure drop,... remove the ground and try the Start position. If it fires,...and dies,.. look for a problem in the ECM trigger signal from the distributor. (What you did above,.. is the same as squirting fuel into the plenum.)
BTW There is no cold start (9th) inj on an 89.
After the pump primes the rail,... (Key in On position) watch the fuel pressure as you ground the ECM side of the injector. The fuel pressure should drop to nothing,... if some or all the injectors are passing fuel. You only need to ground one injector per bank to get the whole bank to open. (If you ground the wrong inj wire,.. you blow the bank fuse.) Grounding the ECM side if the inj while the engine is not running won't harm anything.
After you have primed and tested both banks for a pressure drop,... remove the ground and try the Start position. If it fires,...and dies,.. look for a problem in the ECM trigger signal from the distributor. (What you did above,.. is the same as squirting fuel into the plenum.)
BTW There is no cold start (9th) inj on an 89.
