Fires right up then immediately dies

I have a supercharged 96. A few weeks ago I was driving and the car just died. Started right back up and went on about my business. Couple days later it died when I was pulling into work. Started back up but died instantly. I've had the fuel pump and clogged #5 injector before so I rebuilt the fuel pump again, put a new fuel filter on, and swapped out the suspect injector. It started and seemed to be running fine. Started on my way home and it felt like it wanted to die but did not. So limping it home I found the throttle response to be intermittent (surging between normal power and very little power. Now it still starts right up then dies right away. Replaced the fuel pressure regulator to no avail. Pulled the trouble codes and came up with P1645: 1. Boost control solenoid circuit 2. EVAP solenoid output circuit. They are both on the oxygen sensor fuse but it is fine. Could either of these components cause the start and die symptom? Can't find any vacuum leaks. I don't think it's the injector because I've had that problem before and it caused a severe misfire. If anyone has dealt with this before I'd appreciate your two cents.

Sounds like you have some brittle wiring in the engine harness somewhere. That's just a wild guess, but the problems all seem to come from that area. Inspect all of the harnesses for something that doesn't belong (resting on an exhaust manifold?), and especially the exposed wires near the firewall connector.

This might help a little as far as your P1645



1996 Buick Riviera | Aurora, Riviera VIN G Service Manual

DTC P1645 Supercharger Boost Solenoid Control Control Circuit

Circuit Description
Output Driver Modules (ODMs) are used by the PCM to turn on many of the current-driven devices that are needed to control various engine and Transaxle functions. Each ODM is capable of controlling up to 7 separate outputs by applying ground to the device which the PCM is commanding ON. Unlike the Quad Driver Modules (QDMs) used in prior model years, ODMs have the capability of diagnosing each output circuit individually. DTC P1645 set indicates an improper voltage level has been detected on ODM A output 5, which controls the supercharger Boost Control Solenoid.

Conditions for Setting the DTC
•The ignition is ON.
•An improper voltage level has been detected on ODM A output 5 (the Boost Control solenoid control circuit).
•The above conditions are present for at least 30 seconds.
Action Taken When the DTC Sets
•The PCM will not illuminate the malfunction indicator lamp (MIL).
•The PCM will store conditions which were present when the DTC set as Failure Records data only. This information will not be stored as Freeze Frame data.
Conditions for Clearing the MIL/DTC
•A History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
•The DTC can be cleared by using the scan tool Clear Info function.
Diagnostic Aids
Check for the following conditions:

•Poor connection at the PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
•Damaged harness. Inspect the wiring harness for damage.
•If the harness appears to be OK, disconnect the PCM, turn the ignition ON and observe a voltmeter connected between the Boost Control solenoid control circuit and ground at the PCM harness connector while moving connectors and wiring harnesses related to the Boost Control solenoid. A change in voltage will indicate the location of the malfunction.
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.

2.Normally, ignition feed voltage should be present on the output control circuit with the PCM disconnected and the ignition turned ON.
3.Checks for a shorted component or a short to B+ on the output control circuit. Either condition would result in a measured current of over 800 milliamps. Also checks for a component that is going open while being operated, resulting in a measured current of 0 milliamps.
4.Checks for a malfunctioning boost control solenoid.
15.This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.
DTC P1645 Supercharger Boost Solenoid Control Control Circuit Step
Action
Value(s)
Yes
No

1
Was the Powertrain On–Board Diagnostic (OBD) System Check performed?
—
Go to Step 2
Go to the Powertrain On Board Diagnostic (OBD) System Check

2
 1. Turn OFF the ignition switch.
 2. Disconnect the PCM.
 3. Turn ON the ignition switch.
 4. Using a J 39200 Digital Multimeter, measure voltage between the boost control solenoid control circuit at the PCM harness connector and ground.
Is voltage near the specified value?
B+
Go to Step 3
Go to Step 6

3
 1. Connect the the digital multimeter to measure current between the boost control solenoid control circuit at the PCM harness connector and ground.
 2. Monitor the current reading on the Digital Multimeter for at least 2 minutes.
Does the current reading remain between the specified values?
0.05–0.8 Amp

(50-800 mA)
Go to Step 11
Go to Step 4

4
 1. Turn OFF the ignition switch.
 2. Disconnect the boost control solenoid (leave the PCM disconnected).
 3. Turn ON the ignition switch.
 4. Using the Digital Multimeter, measure voltage between the boost control solenoid output control circuit and ground.
Is voltage at the specified value?
0 V
Go to Step 10
Go to Step 5

5
Locate and repair short to voltage in the boost control solenoid output control circuit. Refer to Repair Procedures in Electrical Diagnosis.

Is action complete?
—
Go to Step 16
—

6
 1. Turn OFF the ignition switch.
 2. Check the ignition feed fuse for the boost control solenoid.
Is the fuse blown?
—
Go to Step 7
Go to Step 8

7
 1. Locate and repair short to ground in ignition feed circuit for the boost control solenoid. Refer to Fuse Block Details in Electrical Diagnosis.
 2. Replace the fuse.
Is action complete?
—
Go to Step 16
—

8
 1. Disconnect the boost control solenoid.
 2. Turn ON the ignition switch.
 3. Measure voltage between the ignition feed circuit for the boost control solenoid and ground.
Is voltage near the specified value?
B+
Go to Step 9
Go to Step 13

9
 1. Check the boost control solenoid output control circuit for an open or a short to ground.
 2. If a problem is found, repair the boost control solenoid output control circuit. Refer to Repair Procedures in Electrical Diagnosis.
Was a problem found?
—
Go to Step 16
Go to Step 10

10
 1. Check for the following conditions:
◦The boost control solenoid output control circuit for a poor connection at the PCM.
◦The boost control solenoid output control circuit for a poor connection at the boost control solenoid.
◦The boost control solenoid ignition feed circuit for a poor connection at the boost control solenoid.
 2. If a problem is found, replace loose terminal(s) as necessary. Refer to Repair Procedures in Electrical Diagnosis.
Was a problem found?
—
Go to Step 16
Go to Step 14

11
 1. Turn OFF the ignition switch.
 2. Reconnect the PCM.
 3. Disconnect the boost control solenoid.
 4. Turn ON the ignition switch.
 5. Connect a test light between the boost control solenoid output control circuit and the ignition feed circuit at the boost control solenoid harness connector.
 6. Using the scan tool outputs test function, cycle the boost control solenoid output ON and OFF.
Does the test light flash ON and OFF?
—
Refer to Diagnostic Aids
Go to Step 12

12
 1. Check the boost control solenoid output control circuit for a poor connection at the PCM.
 2. If a problem is found, replace loose terminal. Refer to Repair Procedures in Electrical Diagnosis.
Was a problem found?
—
Go to Step 16
Go to Step 15

13
Locate and repair open in ignition feed circuit to the boost control solenoid. Refer to Repair Procedures in Electrical Diagnosis.

Is action complete?
—
Go to Step 16
—

14
Replace the boost control solenoid. Refer to Boost Control Solenoid.

Is action complete?
—
Go to Step16
—

15
Replace the PCM.

Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming.

Is action complete?
—
Go to Step16
—

16
 1. Review and record scan tool Fail Records data.
 2. Clear DTCs.
 3. Operate the vehicle within Fail Records conditions as noted.
 4. Using a scan tool, monitor Specific DTC info for DTC P1645 until the DTC P1645 test runs.
Note test result; does the scan tool indicate DTC P1645 failed this ign?
—
Go to Step 2
System OK

Thanks for the help fellas. Replaced the bypass valve and no luck. Been too cold to mess with it so I'm taking it to a shop. When making the appointment the guy said he would guess it's a VATS problem. Realized after talking to him that it has a remote start so the bypass has already been done, right?

MFFDVR wrote:

Realized after talking to him that it has a remote start so the bypass has already been done, right?

Not necessarily. There are a couple different ways to bypass. Some work forever (ie always bypassed/hardwired), some only with the remote start module (the 'right' way)... some actually take a key and lock cylinder and wire it all in taped inline somewhere... If somebody did a hardwired bypass it's certainly possible that it's come undone.

But if it was vats wouldn't it just not start at all?

VATS will disable the fuel pump. So it's possible for it to get enough drips of fuel to start, but not keep running. VATS should also disable the ignition module, though... at least I thought so. A bypass on a remote starter may feed the ignition module directly.

What's your fuel pressure when this happens? If you bypass the fuel pump relay and wire the pump to run full time, what's the fuel pressure? (second method forces fuel pump to stay on, bypassing VATS and the ignition-fed relay, so don't drive it this way) You can find the fuel pump relay under the back seat, pull the relay out and put a heavy gauge jumper wire in where the relay was.

(if it stays running, measure fuel pressure at idle with regulator's vacuum line disconnected and plugged)

Fuel pressure is definitely low. That led me to new pressure regulator, filter, and pump rebuild. I will try jumping the relay and put the pressure tester on. Hopefully I can get that done on my lunch break today.

My '96 Camaro had an issue where it would start, run for a few seconds and shut off on its own. It wouldn't stall, just cut the ignition completely. Sometimes it would run a couple minutes, and the car would drive but would have no power and delayed throttle response. Then it would just cut out at random. I also had several weird DTC's relating to Throttle Position, Transmission and a few others I cant remember. Replacing the PCM cured the problem but I have no idea what the issue was with the PCM. I would check your grounds. I think the computer issues were a result of loose and corroded grounds everywhere. I would check them if you have not. Not suggesting you swap PCMs because my problem may have been unique but your symptoms sound similar. Does your car appear to be stalling(rough stall) or cutting the ignition?

Problem solved! Jumped the fuel pump relay and could hear it running. Car still wouldn't run. Fuel pressure with pump on was only about 7psi. With key on it dropped back to 0. Decided I'd better pull the pump and look it over and BiNGO! Appearantly when I was squeezing the assembly back into the tank the tube from the pump to the assembly loosened and had come completely disconnected by the time I got the car home. Feel kinda dumb now, but the free fix makes me plenty happy. Again, thanks for the help fellas.

Glad you found the problem, and that my advice was helpful!

Uuuggghhh! Right back to starting and dies out after a few seconds. First thing I did was make sure the pump was still connected and it was. Could not here pump running so I rebuilt it again. The fuel filter, relay, and pressure regulator are new. Last time I drove it it ran like complete shit and the SES started flashing. Only codes are random misfire and bad O2 sensor heater element. The O2 sensor code has been there quite some time. Never seemed to give me any issues. Replaced the plugs and plug wires. Checked to make sure all the coils fired and everything seems good. Now it starts right up and purrs like a kitten but dies shortly there after. All my old codes are gone but can't cycle away the misfire code because the car won't stay running. I can here the fuel pump relay engaging and the pump priming, but can't here the pump running after it starts. Anyone have a clue why the pump would shut down after priming?

This may not be very helpful, but perhaps a faulty relay? Something to check.

Replaced the relay trying to fix a previous problem so turns out the old one was good. Now I have two and it acts the same on either one.

I would connect a fuel pressure gauge and see where the fuel pressure is when it dies.

So got a break from the raIn today and hooked up the trusty fuel pressure gauge. During priming it goes to 50psi. after the car starts it drops to about 42-43. Surprisingly no drop when the car dies. While it runs for a few seconds it runs very smooth. With new plugs and plug wires I am stumped.

So that tells me it might be related to ignition. Will it start right back up, or is there a certain amount of time when it won't start? If it doesn't want to start, check for spark. If the fuel pressure is good, the only other fuel related problem I can think of would be if the injectors weren't being pulsed. Might be the PCM in that case.

I wonder if this is the wiring harness problem again - the one at the ignition module where the wires work harden over time and break inside the insulation. We had a thread on this.

What to do is check the wiring harness connector at the ignition module for wire broken inside the insulation. there are a lot of wires so the check will take a while.

Albertj

It starts right back up every time. Wire seem fine. Spark plugs were fouled I assume due to when the fuel pressure regulator was bad and maybe the bad O2 sensor. O2 sensor is the only code I have now besides the random misfire. I think the misfire is gone because it runs very smooth for a few seconds. Could the catalytic converter be bad? Would that keep the car from running? Would disconnecting the exhaust at the manifold be a plausible way to test this theory?

Wires to the ICM and on the fire wall are what I meant seem fine.

And when it dies the rpms slowly fall then it stutters and clunks and dies.