Screaming Fuel Pump
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Thread: Screaming Fuel Pump

  1. #1
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    Screaming Fuel Pump

    After having got the car up and running on Sunday morning I decided to drive along to the S.E. meet and along the way my fuel pump started making a load whining / humming noise.

    This is accompanied by a massive fluctuation in fuel pressure withn the gauge reading second by second changes of 60 psi dropping to 40-50-60-30.

    I'm unsure whether its the fuel pump itself or anything else that may be causing it, i.e. relay or wiring.

    If I start the engine and test the voltage at the pump I assume I should get a constant reading. If I'm testing the pump and the voltage is fluctuating at the same time as the pump is whining then can I assume that it is related to the power the pump is receiving?

    I also want to rule out a crushed return line, if I disconnect the return line to the tank and feed it straight out the of FPR into a can then if the pump stops screaming I know this could be the cause.

    I know I could run wires straight from the battery to the pump but I am hard pushed to find any that are long enough and meaty enough. I suppose I could always disconnect the power line from the amp in the back and use the body as an earth couldn't I?



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  3. #2
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    sounds like the pump is running dry for some reason to me, thats when they get noisy, using the amps live will work though to test it

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    either pump not getting a constant petrol flow or......
    not sure but what rgulates the 12v output from the relay? i know sometimes alts send out too much voltage when the regulator goes, could this send a higher voltage to the pump?

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    dicko has a good point there, because rob has had to actually wire up his own fuel pump relay, this is a throttle body install.

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    The relay has the following connections, +'ve (straight from the battery), negative (from the DTA ECU - switched earth) and the feed to the fuel pump.

    I did notice that the relay was incredibly hot, pretty much too hot to touch.



  7. #6
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    what rating is the relay mate? sound like its a bit over worked

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    its a stock vauxhall XE relay.

    you didnt mention the switch positive, thats just to ignition yeh ?

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    maybe an earth prob then? either on the pump or the relay itself? have read o the dta forum that its agood idea to earth the ecu casing seperatly aswell as the loom earth you get

  10. #9
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    Originally posted by 0ddball
    its a stock vauxhall XE relay.

    you didnt mention the switch positive, thats just to ignition yeh ?
    I dont think there is a switch ignition is there? I think it switches through the DTA earth.

    (I'm not sure but will double check tonight)



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    yup, just uses the dta to switch the relay

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    coolio



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    it has a switch positive too, remember the pump and or the engine ran all the time when we first wired it up, even with the ignition keys taken out.

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    shouldnt need a switched live though, should be able to work purely off the switched earth from the ecu, maybe its the vaux fuelpump relay, could you not jst use a normal five pin relay?

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    Well it looks like I've got to the bottom of it.

    The problem stems from a bracket I made for the FPR. Basically due to the FPR's position on the bracket the fuel line out of the return end of the rail had a sharp bend in it. It wasn't kinked but it was far from "straight through". Therefore I reckon the pressure would build up in the line and force some through to the FPR while putting additional strain on the pump.

    BTW I checked the relay there is definately no switched +'ve, only a switched earth and the relay is off when the ignition is off.



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    been out in it yet? fully sorted? isnt it nice when you fix something for free!

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    I've been out for a test drive and taken all the way to 7750rpm seems fully sorted, no whining, no loss of power, sits at 60psi.

    Indeed, fixing a problem for free almost makes up for all the overpriced items you buy time to time.



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    could do with some of that right now i can tell ya! glad you got it sorted, btw was that full throttle all the way to 7750?

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    lmao it suuuuuuuuurrre was partner.

    You'll get it sorted Lee, what state was the engine in?

    I should be going to see Steve Greenalds soon.



  20. #19
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    ts all but cut up now matey! engine is yet to be opened up, but the cam belt has jumped a few teeth so fingers crossed, think i'll be ok though as omegas have mighty deep pockets in the pistons, gonna do the head while its out, oh and solid lifters

    havent told steveg yet, i'll have to mail him some pics, let me know how you get on down there mate

  21. #20
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    Will do, no problem. I might mention it too him when I see him.



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