Fuel Filter light - what does is measure?

Discussion in '6.9L IH & 7.3L IDI Diesels' started by derjackistweg, Jul 6, 2017.

  1. Macrobb

    Macrobb Full Access Member

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    Hang on, though.... The wire marked "ignition switch" should simply be key-switched power. While not great, I'd bet you could use that one and have it work, if the pump doesn't draw too much.

    Remember, the controller grounds the white wire to trigger the glow plugs...
     
  2. laserjock

    laserjock Almost there... Supporting Member

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    While I agree it would probably work. I have to say I personally would consider it a hack. The problem is if something happens to that circuit, you loose a lot of things. Really all can be avoided with a $3 Bosch style relay and a fuse in the power line for good measure. My 2 cents.
     
  3. madpogue

    madpogue Full Access Member

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    You would use that key-switched power as the trigger to a RELAY for the pump, which is how you should do it no matter what you use.
     
  4. derjackistweg

    derjackistweg Full Access Member

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    Update:
    I wanted to get a complete peace of plywood from the hardware store. As I knew of the Fuel filter light, I was extremely light on the gas pedal. When I parked the truck Fuel Filter light stayed on - while driving it was always going off after some time light on the throttle. :(
    So after coming back I started the truck, it strated right up :Thumbs Up
    I vent out of the truck to let air out of the Fuel Filter shader valve. Too late:frustrate engine died :frustrate
    Electric Pump jumped to pump air out of the filter and lines.
    So air out of the lines. Starting right up :Thumbs Up
    Died in seconds :frustrate

    As I carry a buch of stuff for every kind of repair in my truck - I did what I wanted to do since weeks (really :confused:?). Install a relais in the electrical installation of the electric Pump. :rtfm
    [​IMG]
    You see I am a Pro!:smash:

    I also changed the pre fuel filter. It is - of course also - new, shy of less than 2000 miles. Fuel out of that filter looked great.

    I drove just 2-3 miles but on the last couple of the it came always on when on the throttle. So I think it is fixed. I curious because I ran the other way 1000 mile w/o a problem. Let´s see :peelout
     
    Last edited: Jan 12, 2018
  5. derjackistweg

    derjackistweg Full Access Member

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    PS: Yes it looks like a disaster, though ist not soo bad. I will move both batteries to the frame and with that new wiring anyway.
     
  6. Thewespaul

    Thewespaul Supporting Member Supporting Member

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    I don’t do this often but...









    ....Told you that you needed a relay for that pump:rolleyes:
     
  7. derjackistweg

    derjackistweg Full Access Member

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    Update [I did´nt drove it since Jan]:
    Actually it all didn´t work cookoo! As I only drove some miles it did not show up. This is my investigation. Maybe it did never really work- at least since the replacement engine went in last year. I remember that the Fuel Filter light did came on in the past, but "no issue". This probably due to stop and go and never really loger time wot.

    The Fuel Filter light is directly behind the steering wheel, so it cannot be seen in my normal driving position.
    • I investigated a false automatic fuse that I installed in the setup as seeing above. The fuse was sitting on close position but was actually open :frustrate New one in and measured ~12 V going out of the fuse "box".

    I recently wanted to to dive it and after 20 minutes and ~ 10 miles the light came on. Goes on and off (off throttle). :cry:
    • So I measured again. 12v going out of the fuse into the relay. Filter light on!
    • electric pump directly to the battery: Pump running - fuel filter light goes off. Though I did not drive it like that.
    • on #30 @ the relay 12v are present.
    • when engine is running, I measured 87 (pink cable I am correct) no voltage!
    • when engine is running, I measured 86 (if I am correct). The yellow one is the one coming from the GP relay to initialize the relay. 3-4 volt. :shoot:
    • This is for sure not enough, though i haven´t read the specs of this relay. Maybe specification is more like amperage - don´t know. Probably a broken cable, this is strange.... I measured ~10-12 volt at the post of the relay, where this cable is connected.

    The initial problem was probably not the missing relay but the drop in voltage in this cable. Before the whole mess with this truck [2014-2017] I installed the new pump exactly like the old facet was installed.
    BUT a new engine was installed and with it a new cable connection. I installed it with a fuse inline - now I cannot see the now installed cable connection. Maybe good - maybe not. Maybe the, hopefully installed, fuse is just gone. But in that case there should be no voltage instead of 3 volt.

    Raining today - I will look for it tomorrow.

    What can I use instead of the GP relay to trigger the pump? IP shut-off was mentioned ...
     
  8. 79jasper

    79jasper Chickenhawk

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    Yep. Red wire with green tracer.

    Sent from my SM-G892A using Tapatalk
     
  9. derjackistweg

    derjackistweg Full Access Member

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    You mean that this is the color of the IP Pump cable to connect, right?
     
  10. 79jasper

    79jasper Chickenhawk

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    Yes.

    Sent from my SM-G892A using Tapatalk
     
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  11. derjackistweg

    derjackistweg Full Access Member

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    First Investigation: total corrosion on the fuse in the line that is supposed to trigger the relay ...
    No wonder that it restrictes. Let's see what else comes.

    Need another type of fuse, for sure.

    15290735223071596690459.jpg
     
  12. derjackistweg

    derjackistweg Full Access Member

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    Alright, issue has been found.
    I don't know how this cold corrode in that short periode of time.
    Anyway ended up with a watertight fuse at the triggering GP relay. Now I get stable 12 volt to trigger the relay.

    IMG_20180615_175105.jpg

    IMG_20180615_182055.jpg
     

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