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700/900 Series General Forum for the Volvo 740, 760, 780, 940, 960 & S/V90 cars |
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Hollow tapping from fuel rail Duff FPR?Views : 1622 Replies : 30Users Viewing This Thread : |
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Mar 28th, 2018, 14:58 | #1 |
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Hollow tapping from fuel rail Duff FPR?
Hello all, in the midst of winter my 940LPT started making a regular hollow tapping noise once warm, it is heard in the cabin where it sounds like a modern diesel, outside it could also be heard emanating from the left wheel arch, when listening with a stethoscope there's no tapping from anywhere in the engine or the fuel pump. However the exact same noise can be heard from the fuel rail once the engine is warm (it taps when cold but no so loudly).
I've heard the Fuel Pressure Regulator also acts as a pulsation damper and this could account for the tapping. Any ideas? I'm tempted to replace the FPR and see if that does it but not keen on spending unnecessarily. Any info greatly appreciated. |
Mar 29th, 2018, 19:19 | #2 |
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Someone has released the Lesser Spotted Fuel-Pipe Tapper Gremlin into your tank and it has found its way through to the front.
You could try coaxing it out with a new fuel filter and perhaps a new FPR as well and if you feel really enthusiastic, check the filter sock on the in-tank pump to make sure it hasn't collapsed. Other than the noise, is it running ok? If so i would suspect the FPR and then it's up to you whether you live with it or renew it - double-check it isn't something more serious though.
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Mar 29th, 2018, 20:29 | #3 |
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Thanks Dave, it's running fine except for the drumming once warm! I've been over the engine with the stethoscope and with the exception of the fuel rail it sounds like volvo's version of a sewing machine. I'll try your suggestions and see where it takes me.
Myron |
Mar 29th, 2018, 21:07 | #4 |
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You're welcome Myron, i'd try the filter first rather than the FPR although if it's high mileage it might pay to change both as a matter of course.
First because it's cheaper and second because if it has a partial blockage it might be reducing the amount of fuel through the pipes causing vapour locks which could give rise to the petrol equivalent of water hammer that you get in the plumbing at home from time to time. Good luck with it and let me know how you get on!
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Apr 6th, 2018, 17:24 | #5 |
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The trials and tribulations of getting stuff off of an old car! Looked like a five minute job, loosen off the banjo nut, drain the filter, undo the union, bob's your proverbial! Took a bit longer and had to destroy the old filter in the process, unfortunately no improvement re the fuel rail tapping so will have to look at replacing the pressure regulator in due course! Fuel filter had to be done anyway, looked like it hadn't been touched in years!
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Apr 6th, 2018, 17:31 | #6 |
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Silly question - the fuel rail isn't loose and physically tapping on something?
Or perhaps something nearby is making unintentional mechanical contact somewhere and the fuel pipe/rail is resonating at that particularly frequency? Stranger things have happened!
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