spanishvette86

Hi all!!

Thats the problem. The engine cranks but won´t run. Only sometimes it start about 1 second and dies.
I checked today fuel pressure at injection rail, and its about 45 psi.
Spark is ok, fuses are ok, fuel pump its ok, there are no codes ( no 3 times code 12), and i tryed with 3 different ECMs.
Gas filter is new, and my head is really ****ed .
Ill test the injectors later, but i tested it 2 months ago and they were fine too (with a 12V bulb).
Please, i need help, thank you.
Regards from Spain and excuse my english

Its an 86

Partially solved, page 5

Totally solved, page 5

Really Solved Page 5, post 90

onedef92

You say spark is ok, but have you checked to see if the optical part of your Opti is working? If not, here's a real quick and easy test.

Find the connector to your ignition control module (ICM). Find the white wire. Put your DVM on an AC scale and have somebody crank the car. Probe the white wire with the red lead and ground the black lead to a ground.

If you're not getting anything near 5 volts, then the optical sensor portion is fried on your Opti.

If you're getting 5 volts, then check your plug wires/opti with a spark tester to verify the condition of the cap and rotor.

F18tinman

Spanishvette86,

I am going to guess that the 86 in your name means you own a 1986. Make sure your MAF sensor is installed in the proper direction. If you have tried 3 different ECM's, check the computer grounds/connections. Check for contaminated fuel or clogged fuel filter. Check your EGR valve. (If it is stuck open, you can a get low air/fuel ratio on startup). There are a number of things which can cause this. If you have a FSM it can help.

John

jfb

Always include the year vette you are asking help for. Engines need fuel and air and in the correct ratio, spark and spark at the right time in order to start and run. Use a timing light to check for spark and spark at the right time during cranking. Pull a plug wire and bring a grounded wire near the plug wire during cranking to see if you have at least a 1/2 inch (1 cm) spark. Does fuel pressure hold up for a long time after the ignition is turned off? If not, you may have leaky injector/s. Connect a light emitting diode (LED) with a series 680 ohm resistor across each injector plug, cathode of the LED connected to the black wire. During cranking, the LED should pulse. If you have spark, fuel pressure, injectors pulsed and still no starting, remove the spark plugs and do a compression test.

spanishvette86

Ok, thank you!!
I´ll try to do this test. Im asking in Spain about DVM and AC scale, because i don´t know whats that .
I´ll tell you the results

Hi John.
The MAF is ok (its the same to try cranck with or without it on).
The ECM´s ground is ok too (i think i test it 3 or 4 weeks ago).
The fuel has good color (the car did about 40 kms with it too), and the fuel filter is new.
The EGR thing...what could i do to test it?.
Thank you,regards

Javi

Ok, ill try to do this too.
I forgot to put the year, sorry.
And...the fuel pressure its ok after the IGN is turning off.
Thank you, regards

spanishvette86

One more thing...could i do a compression test by myself?
What do i need?
Thank you!!

AGENT 86

Does the SES light up at all ??

spanishvette86

Hi Dan, yes.
And when i try to cranck, anti lock light is on too.

floridamale

You have checked for spark at the plugs, you have fuel pressure at the rail, have you tried starting fluid to see if it starts up if it dose it would indicate a fuel delivery problem. You could have a shorted injector; you could try disconnecting them one by one to see if it starts. Good Luck

spanishvette86

I gave to the car fuel by throttle body and the car started.
And ill test one by one today all the injectors.
Thank you.

floridamale

If the injectors have shorted it can shut down that bank, you also should check if the fuse is good in the pannel you will have 2 one for each side,

spanishvette86

Both fuses are ok.

spanishvette86

Look what i found today.
I don´t know about ignition modules, but this one seems not too good, isnt it?
Could it be the cause of the problem?







The spark is still good at the plugs.

F18tinman

Spanishvette86,

That HEI module does not look too good. I will bet the connectors are also corroded. Clean all of the contacts. The FSM has a testing procedure but it is very long. If you are getting spark, you have eliminated part of the problem. I would start with that corroded module and work from there. I have a 1987 and will be more than happy to scan in the test pages if you need it. If someone on here has a 1986 manual, it may be better (although I do not believe there are differences). Good luck,

John

LD85

Also make sure your oil pressure sensor at the back of the intake is not corroded.

spanishvette86

Thanks John, you are so nice.
I have Haynes and the one you can see at pics. I bought today at rockauto that module and condenser...hope it will resolve the problem.
Thanks for your help.

Javi

Ok, ill look it to. Thank you

AGENT 86

The ECM needs a reference signal from that module, before it will fire the injectors. Looking at those connectors, it's possible that a poor connection or partially failed module, could be your problem.
All the info you need, is on my website.
http://members.shaw.ca/corvette86/

F18tinman

Spanishvette86,

I scanned the testing procedures into a pdf format but I cannot attach it to this post. PM me your email and I will send them to you.

John

spanishvette86

Thanks Dan!!
Im waiting to the new module from Rockauto.
Take a beer

PM sent, thanks John, and take a beer too

spanishvette86

Another question.
If this

or this


are bad...could be good spark at plugs?

Is possible to test this pieces?

Thank you!!