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420A 420 N/T manual transmission fuel pump relay/ MPI relay, how to diagnose and locations

Posted by langelg6, Feb 23, 2020

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  1. langelg6

    langelg6 Proven Member

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    hello I have a 95 talon 420a FWD N/T and manual transmission

    car pretty much died under WOT and wouldn't start. no mechanical whirring of the fuel pump when key is on run position and pulled a fuel line at the fuel rail, started it and was bone dry. before I go and drop $100 on a wally fuel pump. I would like to know how to diagnose the relays associated with the fuel pump

    I have been confused as to which is my fuel pump relay.. I think its the black box on the firewall next to a grey relay but I have been reading that the fuel pump relay is on the passenger seat next to their leg... Once I track down these relays how would I test for power or what is it I would exactly be doing to diagnose?? sorry if I sound like an idiot.
     
  2. smbgsx

    smbgsx Proven Member

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    I don't have any info for the NT cars, but testing the relays is easy.

    Once you find it, remove it and Google a diagram for a relay with the same amount of pins. Apply voltage using a jumper from the battery positive post to the necessary pins. Use another jumper to supply a ground to the switched side of the relay circuit and you should hear a click as the coil inside energizes and closes the contacts. Then use a DVOM to check for source voltage at the pin that would supply voltage to the pump. Anything more than .2 volts dropped from the source is unacceptable generally, and if you get no click or no voltage than you just confirmed the relay is faulty.

    I'd also check any wiring diagrams you can find to see fuses that should be in the fuel pump circuit.

    If the relay works, fuses are good, then move to the fuel pump harness Connector and make sure power is making it to the pump. If it's not you have a wiring issue up stream from there.

    You can also just try to have someone crank engine while you whack the fuel tank with a mallet. Often you can get a couple of starts from a failed/failing pump like that. It works be a quick check without pulling anything apart. If it fires up you've pretty much confirmed the pump is the cause of concern.
     
    Last edited by a moderator: Feb 25, 2020

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  3. ThunderChild

    ThunderChild Supporting VIP

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    Search for the ASD relay as well. 420a have issues with them and cam/crank sensors pretty regularly.

    Can you give us more info about the shut down so we can help with diag more?
     

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  4. smbgsx

    smbgsx Proven Member

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    Service info states the fuel pump repay is left side of the firewall. No fuses inline that wouldn't affect other things you'd notice either.
     

    Attached Files:

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  5. smbgsx

    smbgsx Proven Member

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    I'd check that 30a fuse, the Auto shutdown relay, and the fuel pump relay. Or like I said thump on that fuel tank for a quick check LOL.
     

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  6. 609DSM

    609DSM Proven Member

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    Does your fuse box not have a key code on it? I have a chilton manual if you need me to look anything up and show you any information you're in need of
     

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  7. langelg6

    langelg6 Proven Member

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    would you kindly do that, yea I cant tell what fuses are what
     
  8. langelg6

    langelg6 Proven Member

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    LOL gonna try all of these tomorrow
     
  9. langelg6

    langelg6 Proven Member

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    gonna test the asd relay as well. and was accelerating from first and diet at 100% throttle it was quick no funny noise just went as if someone turned off the key. I have had issues starting up before so I immediately suspected fuel pump... the mechanical whirring of my fuel pump was no longer present and I yanked the fuel line off and tipped into a cup I had in the car and cranked for a few seconds to find the cup bone dry
     
  10. luv2rallye

    luv2rallye DSM Wiseman

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    Those relays are on driver's side of firewall engine compartment. FP relay is to the left (looking from front) of the ASD relay. The ASD relay must be working to even turn on all PCM (aka ECU) functions including the FP relay.
     

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  11. 609DSM

    609DSM Proven Member

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    I can also snap me a picture of my fuse box diag if you need and a picture of my actual fuses for reference. Let me know what exactly you need me to look up in the chilton for you. Give me a little bit I'm at school, when I get a break I'll upload pics of the fuse box diag and fuses
     

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  12. smbgsx

    smbgsx Proven Member

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    @luv2rallye

    didn't look that close, but I thought the ASD relay (which is a proprietary Chrysler thing) only supplies power to the injectors and ignition coils? Not power train control module.
     

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  13. langelg6

    langelg6 Proven Member

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    the fuse box in my engine has no cover, the fuse box by the clutch has no cover and the passenger side fuse box has no cover

    wouldn't some things be slightly different in a 95 2G then the years after
     
  14. 609DSM

    609DSM Proven Member

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    There are small differences from the 2ga to the 2gb n/t eclipse cars. I dont believe the fuses change but I could be wrong. Things that are different I can think of off the top of my head are sensor connections your coolant sensor is a different shape than mine and you FPR connects directly from the fuel rail to the intake instead of being apart of the evap system like mine. Give me one second because it's raining right now I'll get the pictures for ya
     

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  15. 609DSM

    609DSM Proven Member

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    20200225_120227.jpg 20200225_120136.jpg 20200225_120128.jpg
     

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  16. 609DSM

    609DSM Proven Member

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    A screenshot was easier so here is this. Screenshot_20200225-121114_Samsung Internet.jpg
     

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  17. 609DSM

    609DSM Proven Member

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    Read up on another thread. Those relays should be near the coolant reservoir near the firewall driver side
     

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  18. luv2rallye

    luv2rallye DSM Wiseman

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    Good catch! I misread the diagrams. For the 2g NT it supplies power to the alt field coil, ignition coil, both O2 sensors, and injectors. It does go to the PCM but only as a signal to say that it's activated.
     
    Last edited: Feb 26, 2020

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  19. langelg6

    langelg6 Proven Member

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  20. langelg6

    langelg6 Proven Member

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    So I ordered a wally anyway as I plan to turbo in the future still no start.. poked the shrader valve and got shot with fuel so pressure at the rail seems good, pulled a spark plug with wire still attached poked the valve cover while my dad was cranking and nothing touched the strut tower with a screwdriver instead and still nothing.... dad was cranking the car and I felt the relays and what I felt was the fuel pump relay click 2-3 times as soon as he turned the key on then it would stop while he was still cranking, I can't remember if the ASD relay came on at all or acted the same way as the fuel pump relay... after I took a screwdriver to each injector and no visible clicking on each injector.. my conclusion is ASD relay, what do you guys think?
     
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  21. 609DSM

    609DSM Proven Member

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    So if you have fuel pressure that's good! So no spark, have you tested your coil pack at all? My first assumption would be to inspect plug, test wire then test coil pack and then if everything checks out test the relay. Entirely possible the relay is bad but you cant solely go off an audible test, it could all be working properly.
     

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  22. luv2rallye

    luv2rallye DSM Wiseman

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    Test the voltages on the ASD relay wires. The 14 gauge flexible red/black (pin 8) and the 20 gauge black/white (pin 6) should always have +12V (whether relay is plugged in or not) as they go straight to the battery through a 30 amp fuse. With relay plugged in, the 20 gauge red/white (pin 4) should go from +12V to near zero while the key is ON (this turns the relay on). The 14 gauge flexible black/red (pin 2) is the relay output and should have +12V while the relay is on.
     

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  23. langelg6

    langelg6 Proven Member

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    ok so I had no idea my 95 was obd 2 at one point and I had tried to run diagnostics but it didn’t power my obd 2... So I swapped the 10amp “room light fuse” and voila it’s pulling codes

    to my findings it seems to have thrown a code for the ckp or cmp sensor. I wrote the exact code and what it said in a notebook at home so I need awhile before I can relay that info to you guys

    At first my thesis was ASD relay but now I believe my culprit is the crank sensor due to pulling codes from the engine.... My fuel pump is indeed priming and getting pressure at the rail as I just put a wally 255 lph pump... I do not believe any injectors are firing as I used the long rubber screwdriver method and did not hear any visible clicking but not too sure on that conclusion with the injectors... No spark for sure just used a test light, took a plug out while coil wire was still attached and attempted to arc it on to the valve cover and same thing with a screwdriver on the strut tower.. nothing.. I am not home but I am gonna have dad try and start my car and ask him to pay attention to my rpms while cranking if nothing happens I’m pretty sure the ckp sensor is the culprit but I am also gonna replace the ASD relay and cam sensor just for preventative maitnence as I hear of these as a common failing point for these 420a’s
     
  24. 609DSM

    609DSM Proven Member

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    What is the code? P0340 is cam positioning sensor. I forget what the crank sensor code is
     

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  25. luv2rallye

    luv2rallye DSM Wiseman

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    That's for the turbo 4g63. The 420A is P0335 (no crankshaft reference signal at PCM) or P1391 (intermittent loss of CMP or CKP).
     

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