I got my neon in April shortly after experienced a bunch of fuel pump fuse issues which got fixed. during that process I put a new fuel pump in and filter. after a couple months my fuel pump when I turned the car on before started made alternating whining and groaning noises with knocks thrown in occasionally. and it also made th car hard to start. I had to turn it on and off several tines to get fuel circulated then it would start fine. this happens today thing in the Morin.g or after its set. when the engine is warm it starts just fine no weird noises just the normal hum. so I warrantyeed the fuel pump put the new one in and a filter. now a few months later its doing it again. I am at a loss. the only thing I can think of is that my downstream o2 sensor pigtail is kinda charred and blackened but idk. if it runs along the fuel pump circuits. any help would be appreciated.

and BTW I'm sorry if there is already a preexisting thread the only access I have to the internet is through my android and when I try to search it throws me to the top of the page.

thanks.

 

The wires supplying power to the O2 sensors is the same circuit supplying power to your crank position sensor, your cam position sensor, your VSS, your auto shutdown relay, and your fuel relay (and a few others). A short anywhere in that circuit will shut the system down completely and/or create strange and weird effects that come and go as the wires bang around under the hood. This problem is notorious for older neons.

In other words, yes you really need to check the wiring harness for both O2 sensors as well as the wires going into all the other sensors I mentioned as if they are cracked, exposed, badly connected, dirty/broken connectors to the sensors, then they need to be properly covered, cleaned, tightened, replaced, etc.

 

Ok update. Finally found a downstream pigtail had it mailed from Missouri. Got it put on and check engine light is off(for now) tomorrow I am doing the fuel pump AGAIN and hopefully I should be good to go. Have been having some really rough idle and bad gas mileage that's somehow cold weather related got an egr ordered from junkyard 10 Bucks so ill see what that does. And I understand what you mean by the older neons being notorious for wiring issues. I have fixed and taped almost half my wires on the car and heat shrink connectors are my best friends.

If anybody has an idea bout the rough idle I'm completely open to suggestions/advice. I have a new map/iat new air tempsenzor and neither has corrected the issue. Mostly does it when cold. Idles between 500 and goes up real high to 2500. Its an intermittent thing too it doesn't do it constantly.

 

Try checking the Throttle position sensor. The one right next to the IAT. Mine was doing this when it was going bad - no error codes thrown.

 

Ok i will check the tps. Got the downstream o2 code back. And i checked the codes it showed po140 and a bunch of little circles that said mis fue ccm egr o2 heater and cat. I have a straight pipe so i understand the cat. Im also gonna che k the gounds and redo them all.

 

If the TPS is OK, the next thing to check is the EGR. Error codes are not always thrown if it starts going wonky. Sometimes you can clean one, sometimes that won't help.

Check all the vacuum lines, especially the ones going into and out of the Charcoal canister as they will sometimes get a small rubbed hole in them and will not always trip a code. My leak was on the hose coming out of the charcoal canister right in the middle of the passenger fender well next to the clip that held it in place. I only found it when I physically pulled it out and checked it end to end.

 

Ok so I haven't made it as far as chechlking the tps because my car died on me leaving my dads. Before this happened I redid grounds and fixed some wires under my fuse box ie. Electric parts cleaned them and reconnected some wires that were chewed ss the whole thing connectors and wires were electrical taped and drenched in oil as well as the pcm connectors. Cleaned all fixed where broken. Vacuum line from egr is fine dad looked at it. My pump has been making noise for a couple months. When it died I checked fuses got power to everything but fuel pump didn't come on. So I warrantyeed it out and put the new one in. NO POWER TO PUMP. Relays are good switched the horn asd and fp relays all Wound no power to pump. My bf and I looked at the fuse box and he had me turn key on and then hr took out the fp fuse the stuck it back in and when he did my check engine light came on and battery light and I heard a weird chittrring noise come from under yhr throttlebody area. My battery light and ce light came on after I connected the battery back up took him to work and it died.the lights and reconnecting of battery terminals was prior to its shutdown. Still cant hear the pump kick on. I did the dodge key dance got 7 codes. 12 42 44 23 22 24 55

 

I have found my problem. The computer connector on the right is missing the clip that holds it securely in place. Left key on and jiggled that connector pump kicked on. So i dialectric greased the conncetors and now have speaker wire holding it in place. If anybody has the connector or a better way of securing it it is appreciated. Thanks for all help now gotta charge my battery and see how it runs

 

You might try going to a JY and finding a new connector and/or harness to use to replace the loose/missing one.

I know the 95 PCM connector was unique unto itself, but I do not know about 96 -99 PCM connectors and how interchangable they are.

 

I know this is an older thread, but where is this computer?