1990 Chrysler 5th Avenue Firing order

Tiny
ECHRISCO
  • MEMBER
  • 1990 CHRYSLER 5TH AVENUE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 476,421 MILES
What is the firing order for my 90 5th ave?

Also, what would cause it to not get fuel even though the fuel pump is working? When connecting the fuel pump directly to the battery, it gets fuel to the injectors. When hooked up normally, the pump comes on for about 1 second when turning the key, then shuts off.
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Wednesday, November 11th, 2009 AT 4:47 AM

4 Replies

Tiny
CARADIODOC
  • EXPERT
Sorry for the delay in replying.

Sounds like it's working properly. The injector(s), coil(s), alternator field, O2 sensor heater, and fuel pump or pump relay receive 12 volts through the Automatic Shutdown (ASD) relay. The ASD relay is turned two times by the engine computer. First, it turns on for two seconds when the ignition switch is turned on to insure fuel pressure is up, then it turns off until the computer sees engine rotation, either cranking or running.

This is Chrysler's very effective and reliable system to prevent fires in the event of a crash. If the fuel line is ruptured, there will be no fuel pressure. Without pressure, the injectors won't spray fuel and the engine will stall. The computer will no longer receive pulses from the crankshaft position sensor so it knows the engine stopped, and it turns off the ASD relay. 12 volts is turned off to the fuel pump so no raw fuel is pumped onto the ground.

The most common mistake people make when diagnosing a no-start condition is looking for missing fuel pressure OR missing spark, then troubleshooting that one system. Each of these systems gives very little trouble. You must check for both spark AND fuel. When both are missing, suspect a defective crankshaft position sensor on the rear of the transmission bell housing (3.3L) or in the distributor (3.0L). When replacing it in the 3.3L, the air gap is critical. New ones come with a cardboard spacer glued on to set the gap. It will be sheared off harmlessly when the flywheel turns.

Depending on which engine you have, the firing order is printed on the top of the distributor cap for the 3.0L engine or is controlled by the engine computer on the 3.3L engine. That one fires the three coils in the proper order. Each coil fires two spark plugs at the same time.

Caradiodoc
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Thursday, November 26th, 2009 AT 11:31 PM
Tiny
AMERIGO
  • MEMBER
We got the book, and found the firing order.

We've replaced several sensors without any luck. I don't think the one you mentioned was one of them. We have changed the MAP, O2, and cam sensors.
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Friday, November 27th, 2009 AT 6:41 AM
Tiny
CARADIODOC
  • EXPERT
Please reread my reply. Have you checked for spark? You absolutely can not only troubleshoot lack of fuel. You MUST check for BOTH spark and fuel, otherwise you will very likely be troubleshooting the wrong circuit.

You still haven't described the symptom either. Does it crank but not start? Does it start but only run for two seconds? Which engine do you have? The 3.0L is a Mitsubishi engine; the 3.3L is a Chrysler engine. They have very different circuitry, common problems, and troubleshooting steps.

The sensors you listed are not relevant to a no-start condition so I'm wondering what the actual problem is. The engine will start, and run (poorly) with a defective MAP sensor as long as the accelerator pedal is in motion, not held steady in any one position. The O2 sensor doesn't fine tune fuel metering until it reaches 600 degrees and the engine coolant is up to at least 180 degrees. The V-6 engines don't use cam sensors.

Please describe the symptom you're having and which engine you have. That will help with making a diagnosis.

Caradiodoc
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Friday, November 27th, 2009 AT 1:25 PM
Tiny
AMERIGO
  • MEMBER
I have a 3.3L.
One of the first things we did is look for spark. There is.
The engine does start of about 2 seconds then dies.
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Friday, November 27th, 2009 AT 7:29 PM

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