getting desperate for help- 90 no start
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Joined: Feb 2007
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From: Woodville Alabama
getting desperate for help- 90 no start
Starting to get desperate for help here. My problem is I live in a very rural area and unless I repaint the vette yellow and green and label it John Deere, my choice of Vette mechanics are slim. The local dealer I wouldnt even think of taking it to. Closest "big city" is about 60 miles and would have to towed. Please see my post on code 46 http://forums.corvetteforum.com/show....php?t=2071524
What has change:
After clearing codes,code 46 or any other no longer there. None in ccm either.
Checked fuel pressure with guage-48PSI
Injectors all within spec.
My questions:
Have power to injectors, but test light does not blink on and of when cranking engine. Should it?
If I probe ck229 from the ecm, shoud it have power with ignition on? It does not now.
Would one of these vats bypass modules get my injectors enabled(if they are disabled) or do they just bypass the starter engagement problem? Mine does crank, just no start.
Any help given to get this running would be apreciated!!!!!
What has change:
After clearing codes,code 46 or any other no longer there. None in ccm either.
Checked fuel pressure with guage-48PSI
Injectors all within spec.
My questions:
Have power to injectors, but test light does not blink on and of when cranking engine. Should it?
If I probe ck229 from the ecm, shoud it have power with ignition on? It does not now.
Would one of these vats bypass modules get my injectors enabled(if they are disabled) or do they just bypass the starter engagement problem? Mine does crank, just no start.
Any help given to get this running would be apreciated!!!!!
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Joined: Feb 2007
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From: Woodville Alabama
Melting Slicks
Joined: Dec 2004
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This is just a shot in the dark, but is your engine computer working OK?
My 1990 Corvette sat in the driveway all summer in 2005 because it either wouldn't start or would start and run only 10 minutes. A mechanic replaced the computer. A year later, the replacement computer went bad and then I learned from another mechanic that the heat of the engine melts the soldered connections in the computer. Instead of replacing computers every six months to a year, I always raise the hood of the car when I get home and put an ice pack on the computer if it's really hot when I get home. Sounds stupid. But I'm still using the same computer that I installed nearly two years ago and the car runs fine. Of course, your problem could be something else. Just my $0.02 worth.
My 1990 Corvette sat in the driveway all summer in 2005 because it either wouldn't start or would start and run only 10 minutes. A mechanic replaced the computer. A year later, the replacement computer went bad and then I learned from another mechanic that the heat of the engine melts the soldered connections in the computer. Instead of replacing computers every six months to a year, I always raise the hood of the car when I get home and put an ice pack on the computer if it's really hot when I get home. Sounds stupid. But I'm still using the same computer that I installed nearly two years ago and the car runs fine. Of course, your problem could be something else. Just my $0.02 worth.
Safety Car
Joined: Jan 2006
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From: Mt Laurel NJ
St. Jude Donor '06-'07
Is there a auto parts place near you wee you can rent/borrow a scanner? If your Coolant Temp Sensor is not working correctly, it could be flooding the engine. When tring to start the car, do you smell gas? You say the injectors are OK, what do they read? Also, like the guy above, see if you can borrow a know good ECM.
Randy
Randy
Last edited by RandyJ75; Jul 8, 2008 at 11:54 PM.
Team Owner
Joined: Mar 2001
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From: Cincinnati, Oh USA
If you can crank the engine, then VATS isn't involved. Check your injector fuses with an ohmeter. Injectors are pulsed by the ECM from pulses supplied by the distributor. I would check that you are getting those pulses and if not, then check for low resistance on the pickup coil in the distributor. The pulses are supplied by the spark control module in the distributor (from pulses from the pickup coil). You may have a defective spark control module. Auto parts stores can test spark control modules. Solder melts at 600 F, so you got bad info about engine compartment heat unsoldering connections in the ECM.
Last edited by jfb; Jul 9, 2008 at 12:05 AM.
Thread Starter
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Joined: Feb 2007
Posts: 54
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From: Woodville Alabama
Is there a auto parts place near you wee you can rent/borrow a scanner? If your Coolant Temp Sensor is not working correctly, it could be flooding the engine. When tring to start the car, do you smell gas? You say the injectors are OK, what do they read? Also, like the guy above, see if you can borrow a know good ECM.
Randy
Randy
checked resistance in injectors...all are between 16.4 and 16.7 which is within spec.
No smell af gas when cranking
Thanks for your reply
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From: Woodville Alabama
If you can crank the engine, then VATS isn't involved. Check your injector fuses with an ohmeter. Injectors are pulsed by the ECM from pulses supplied by the distributor. I would check that you are getting those pulses and if not, then check for low resistance on the pickup coil in the distributor. The pulses are supplied by the spark control module in the distributor (from pulses from the pickup coil). You may have a defective spark control module. Auto parts stores can test spark control modules. Solder melts at 600 F, so you got bad info about engine compartment heat unsoldering connections in the ECM.
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Thread Starter
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Joined: Feb 2007
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From: Woodville Alabama
Thanks for pointing me to that. According to chart a-3 light should blink when cranking,which it does not. Next step is to check injector driver cicuit,which I will do tomorrow
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Joined: May 2007
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From: LA California
You might try this tip which I found somewhere:
Since the state of the ECM's injector drivers seems to be in question, simply unplug all the injectors, hook a test light between the two contacts in an injector harness and try to start the engine.
If the light doesn't flash I'd say the drivers are fried; if it does flash plug in each injector one by one, cranking the engine after each till the light no longer flashes to isolate a bad injector or harness connection.
Then with all injectors unplugged, you can connect a 14 / 4 == 3.5 Ohm resistor across an injector harness connection along with the test light to see if the ECM driver will still flash the test light; if so the ECM driver is ok.
The ECM has only 2 injector drivers (that´s also why there are two injectors fuses in the fuse box). One is a green cable coming from the brown connector at the ECM and one is a blue cable coming from the brown connector of the ECM giving ground on 4 and 4 injectors.
One bad injector can prevent your engine from starting; see: http://forums.corvetteforum.com/show....php?t=2072870
If the light doesn't flash I'd say the drivers are fried; if it does flash plug in each injector one by one, cranking the engine after each till the light no longer flashes to isolate a bad injector or harness connection.
Then with all injectors unplugged, you can connect a 14 / 4 == 3.5 Ohm resistor across an injector harness connection along with the test light to see if the ECM driver will still flash the test light; if so the ECM driver is ok.
The ECM has only 2 injector drivers (that´s also why there are two injectors fuses in the fuse box). One is a green cable coming from the brown connector at the ECM and one is a blue cable coming from the brown connector of the ECM giving ground on 4 and 4 injectors.
Racer
Joined: Jan 2007
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From: Muskogee OK
Try one quick check of the CCM circuit.
Ground out A - G, scroll to module 1.3 -01. Does it read 0 or 1? If it is 0, the CCM, while recognizing the key resistor and allowing cranking, has not sent a signal to the ECM to allow fuel enable.
Ground out A - G, scroll to module 1.3 -01. Does it read 0 or 1? If it is 0, the CCM, while recognizing the key resistor and allowing cranking, has not sent a signal to the ECM to allow fuel enable.
Team Owner
Joined: Mar 2001
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From: Cincinnati, Oh USA
It is a good idea to put a low power 12v lamp across an injector plug and see if the light pulses during cranking. This checks for 12v pulses out of the ECM and it checks for a good ground in the injector harness wiring. No pulses, no fuel getting into the cylinders. The spark control module has a separate circuit that supplies pulses to the ECM, so that circuit could be defective and you would still have spark at the plugs while cranking which you should also check. No pulses out of the pickup coil, then no spark and no injector pulses. See if someone around can test your spark control module.
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From: Woodville Alabama
It is a good idea to put a low power 12v lamp across an injector plug and see if the light pulses during cranking. This checks for 12v pulses out of the ECM and it checks for a good ground in the injector harness wiring. No pulses, no fuel getting into the cylinders. The spark control module has a separate circuit that supplies pulses to the ECM, so that circuit could be defective and you would still have spark at the plugs while cranking which you should also check. No pulses out of the pickup coil, then no spark and no injector pulses. See if someone around can test your spark control module.
A big thanks to jfb and everyone who helped me with this problem. I was confident that some one here would "hit upon the problem. Hopefully at some point I can return the favore.
While I am at it, does anyone know where I can get this 8A electrical diagnosis supplement. I guess I may need it in the future.
Safety Car
Joined: Oct 2007
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From: :45 minutes from everywhere / E-I-E-I-O
Looks like someone did make the right call...
There is a condition that will disable injectors (on a '94 anyway), so that the engine does not flood. DTC41 open ig control circuit, which I'm workin' on now... (workin' on me is more like it
)
Check your '90 FSM to see if ig control circuit problems will disable injectors.
)Check your '90 FSM to see if ig control circuit problems will disable injectors.
Le Mans Master
Joined: Sep 2006
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
fwiw
my 86 was surging and idle hunting, and I unplugged the elect. spark module while it was running, and it suddenly ran ok. there must be some limp-home mode look up table in the ecm if the module goes bad. You may have had a fault that disabled the spark. Just un plugging it might have gotten it running.
just something to absorb for the future.
just something to absorb for the future.
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Joined: Feb 2007
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From: Woodville Alabama
Your right shrade...Thank you.Unfortunately because I dont have the 8A electrical diagnosing section supplement to my FSM, i couldnt track it to the control module until jfb pointed out directly to me. Hope I didnt sound ungrateful to you and thanks again for your help
