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RIP, Lead Technician
Category: Dodge
Satisfied Customers: 5591
Experience:  ASE Certified Master Technician, L1 Adv Level, Ca Smog License, Chrysler Aftermarket Training.
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Neon: that started to sputter and stall out while..misfire..coil pack

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I have a 2000 Plymouth Neon that started to sputter and stall out while going down the road. On an OB2 scanner it said multiple cylander misfire. The plugs, wires and coil pack has been changed and I am not getting rid of th problem. Now when the engine is cold I can start it and drive for about a half mile and then the problem comes right back. Then you will be lucky to even make it back the half mile before it "dies" all together. When the spark plugs were changed they were covered with a very dark dry carbon that could easily wiped off. There seems to be good exhaust flow coming out the back of the car. I don't believe the converter is plugged. I'm thinking there is just not the proper air/ fuel mixture but don't know what to change. Air filter has been changed. Egr valve? Sensors? What do you think? The more you press on the gas the engine will just stall like its getting flooded.

First, we need to get the engine to stall where you can test for good spark and fuel. You may have a faulty fuel pump. How many miles are on the vehicle? When it stalls, spray some carburator cleaner into the intake by removing the air duct, spraying a liberal amount in, then resecuring it. Crank and see if the engine will momentarily run on the starting fluid. If not, pull a plug wire/coil and check for good strong spark. Let me know your outcome.


Customer: replied 10 years ago.
Reply to RIP's Post: I pulled the wires right off from the coil pack and put a spark tester between it and all the wires. On all of them it would jump at least a quater inch. I don't think that is the prblem. When putting gas into the air inake and cranking the engine it would run but backfire, but if someone holds the pedal down while doing this the engine would take right off. I agree there is a fuel problem. Are yu sure the pump is the first place to start or is there any other sensor or electronic piece that could cause this? his pump will not be a cheap fix. Thanks.

The pump is a common failure, but we do need to verify it's failure. Do you have access to a inexpensive voltmeter? We also need to verify physical fuel pressure and flow with an injection guage, usually sold at parts stores as well.

The probabilities when no fuel reaches the engine can be: Possible ECU (computer), fuel pump, fuel pump relay, wiring, or the fuel filter.

The problem on this vehicle is the fuel filter is part of a pressure regulator unit on top of the fuel tank, so when the fuel pump is deemed faulty, the entire assembly is replaced. Let me know if you have access to any of the above tools, so I can instruct you on the testing. If not, have someone turn the key ON, and listen near the fuel tank underneath for a light buzzing, this indicated the fuel pump is comming on, if no noise is hear, it may be faulty or not receiving power. Try banging gently on the gas tank with a hammer, while someone is cranking, this often will 'shock' the pump into working, and will further condemn it's failure.


Customer: replied 10 years ago.
Reply to RIP's Post: I do have my own voltmeter and I have borrowed the guage. How exactly to test the pressure I am not sure of. With trying to run the engine or just cranking it over?

Alright, hook up the pressure guage to the test port on the fuel rail under the hood, turn the key ON, the guage should read between 35-45 psi - what is your reading. if nothing shows, try turning the key off, then back on, if still nothing, crank it. Let me know the outcome.


Customer: replied 10 years ago.
Reply to RIP's Post: Just turning the key to the on position gives hardly no pressure. Cranking it and starting the engine will bring it to about 45 but in less than a minute, it starts to drop off fast. That is when the sputtering and misfire starts. It will drop to 20 or below and then it will stall. It will not stay running or pressure will go back up until it sits for quite some time. You get same results.

Sounds like the Fuel Pressure Regulator is faulty, but it's part of the Fuel Filter on top of the tank. Another concern is that it may be your only problem, and isn't an expensive part, but there's a small possibility that the check valve in the Fuel Pump is bad, or the pump itself. Therefore, we replace the entire Fuel Pump Module with the pressure Regulator/Filter to keep from removing the tank twice, since there's no testing possible to distinguish between the two failures. If you don't mind removing the tank twice it would be a good investment since the difference in price between the Pump Module and the Regulator is great. Most pump failures I see, cause 0-10 psi at key ON, and cranking. 45 psi sounds like the pump is trying to do it's job. What if you have someone crank the engine and gently bang on the tank after it has stalled and see if it wants to restart and run? Below is a pic of the Regulator/Filter.


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