1991 Fuel Pressure
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Joined: May 2008
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From: Arconate (MILANO) ITALY
1991 Fuel Pressure
Hello guys,
i have a two question for you.
-How much is the right pressure on fuel rail for a 1991 corvette?
-I try to ground pin A on ALDL, the fun is on but the light "service engine soon" not lamp, is off (there is the bulb). I can't read if there are any trouble codes. What will be the problem??
Thank you so much in advance
Max
i have a two question for you.
-How much is the right pressure on fuel rail for a 1991 corvette?
-I try to ground pin A on ALDL, the fun is on but the light "service engine soon" not lamp, is off (there is the bulb). I can't read if there are any trouble codes. What will be the problem??
Thank you so much in advance
Max
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Pin A IS ground.
Does the SES light work when you turn on ignition without the jumper wire between A and B pin?
Connect a wire between pin A and pin B.
Turn on ignition but do not start.
The fan should come on and the Service Engine Soon light should start to flash.
One short flash followed by two long ones means 12.
Every code comes three times.
Last code will be 12.
If it still doesn´t work, try and change with another bulb in there.
Install fuel pressure gauge.
Ignition off for ten seconds. AC off.
Ignition on. Fuel pump will run for two seconds.
Note fuel pressure, with pump running should be 280-325 kPa (41-47 psi) and hold steady when pump stops.
Good luck.
Does the SES light work when you turn on ignition without the jumper wire between A and B pin?
Connect a wire between pin A and pin B.
Turn on ignition but do not start.
The fan should come on and the Service Engine Soon light should start to flash.
One short flash followed by two long ones means 12.
Every code comes three times.
Last code will be 12.
If it still doesn´t work, try and change with another bulb in there.
Install fuel pressure gauge.
Ignition off for ten seconds. AC off.
Ignition on. Fuel pump will run for two seconds.
Note fuel pressure, with pump running should be 280-325 kPa (41-47 psi) and hold steady when pump stops.
Good luck.
Last edited by vette079; Oct 7, 2009 at 08:30 AM.
Le Mans Master
Joined: Aug 2000
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From: Australia
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Joined: May 2006
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When a jumper is connected between A and B, and the light is on steady, there is either a short to ground in circuit 419 (brown/white wire between SES light and ECM), or an open in diagnostic circuit 451 (white/black wire between ECM and B terminal on ALDL).
Last edited by vette079; Oct 7, 2009 at 09:16 AM.
Thread Starter
Instructor
Joined: May 2008
Posts: 118
Likes: 2
From: Arconate (MILANO) ITALY
Pin A IS ground.
Does the SES light work when you turn on ignition without the jumper wire between A and B pin?
Connect a wire between pin A and pin B.
Turn on ignition but do not start.
The fan should come on and the Service Engine Soon light should start to flash.
One short flash followed by two long ones means 12.
Every code comes three times.
Last code will be 12.
If it still doesn´t work, try and change with another bulb in there.
Install fuel pressure gauge.
Ignition off for ten seconds. AC off.
Ignition on. Fuel pump will run for two seconds.
Note fuel pressure, with pump running should be 280-325 kPa (41-47 psi) and hold steady when pump stops.
Good luck.
Does the SES light work when you turn on ignition without the jumper wire between A and B pin?
Connect a wire between pin A and pin B.
Turn on ignition but do not start.
The fan should come on and the Service Engine Soon light should start to flash.
One short flash followed by two long ones means 12.
Every code comes three times.
Last code will be 12.
If it still doesn´t work, try and change with another bulb in there.
Install fuel pressure gauge.
Ignition off for ten seconds. AC off.
Ignition on. Fuel pump will run for two seconds.
Note fuel pressure, with pump running should be 280-325 kPa (41-47 psi) and hold steady when pump stops.
Good luck.
Thank you so much vette 079.
The bulb is ok, the light come on when turn on the ignition. When connect A+B the fan is on but the SES is off.
The last owners change the ECM, but he don't know what ECM is it!!!!
The car have problem at idle. When you run slow the car sometimes turn off, idle is sometimes high and sometimes low...
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Joined: May 2006
Posts: 637
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Thank you so much vette 079.
The bulb is ok, the light come on when turn on the ignition. When connect A+B the fan is on but the SES is off.
The last owners change the ECM, but he don't know what ECM is it!!!!
The car have problem at idle. When you run slow the car sometimes turn off, idle is sometimes high and sometimes low...
The bulb is ok, the light come on when turn on the ignition. When connect A+B the fan is on but the SES is off.
The last owners change the ECM, but he don't know what ECM is it!!!!
The car have problem at idle. When you run slow the car sometimes turn off, idle is sometimes high and sometimes low...
1227727 or 16198260.
The first one is original, the last one is a replacement.
Did they change the memcal as well, or did they put in the original memcal (the little print "board" chip)?
If engine runs OK, check:
Faulty light bulb, you checked it OK.
CKT 419 open, THis is a brown/white wire between bulb and ECM.
On the ECM there are four big connectors.
On connector B, that is one of two in the middle and it should be a red one, there is a brown/white wire in one of the corners.
The connector is also called J2 in the book.
That wire is circuit 419 and should be checked for an open.
If the engine runs, turn off engine, disconnect all ECM connectors, turn on ignition, Probe ckt 419, ECM pin B1 (that is the one where the brown/white wire connects), with test light to ground.
Is the SES light on?
If no, check cluster fuse, faulty bulb, open ckt 419, ckt 419 shorted to voltage or open open ignition feed to bulb.
If yes, faulty ECM connection or ECM.
Check this out and we´ll see what happens.
