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I have had intermittent fuel pump noise for the last 3 years since a new pump and filter was fitted, the usual system fitted at the base of the fuel tank.  For reasons unknown sometimes its noisy as hell, sometimes silent.  I have read the various posts on here as far as I can, but its not that easy to search, despite what some people say!  In summary, I think the advice is  that the peculiar set up of each set can produce resonance in some circumstances, and the way to stop it is to change the set up slightly?  I have the black rubber hoses already, so I wondered about putting a permanent pressure guage into the middle of one of the pipes, as I thought that this might provide a suitable adjustment.  Does anyone have any ideas or comments?

Matt

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1 hour ago, Matt1969 said:

I have had intermittent fuel pump noise for the last 3 years since a new pump and filter was fitted, the usual system fitted at the base of the fuel tank.  For reasons unknown sometimes its noisy as hell, sometimes silent.  I have read the various posts on here as far as I can, but its not that easy to search, despite what some people say!  In summary, I think the advice is  that the peculiar set up of each set can produce resonance in some circumstances, and the way to stop it is to change the set up slightly?  I have the black rubber hoses already, so I wondered about putting a permanent pressure guage into the middle of one of the pipes, as I thought that this might provide a suitable adjustment.  Does anyone have any ideas or comments?

Matt

Hi Matt,

As you have a rubber hose the point is how flexible is it and what is the psi rating of your hose? Anything above 200 psi can give the dreaded Harmonic banging? Sometimes just rerouting the hose can get rid of the noise. Putting a pig tail in the hose if you have enough slack will often do the job. The key issue for me after over 40 years experience of using a Bosch pump is flexibility of the rubber hose and its psi rating and no S/S braid. I have not had the harmonic banging for over 30 years! Can you post a photo of your pipe run?

Bruce

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Hi Matt

The first thing I would do and it is beneficial to the cooling of the pump is locate it on the chassis inside the left hand rear wheel arch its the place I fitted mine when I

was running a 6

Chris

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Matt,

so you have a discharge filter, no suction filter. In a way this helps, the suction side is less restrained. If you have a (very) high flow pump it can still cause issues. which pump do you have and how much liter/hr does is supply at 105 psi?

Waldi

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That does not give any clue Matt; If it is an original Bosch pump the number could be stamped under the clamp.

Waldi

Edited by Waldi
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17 hours ago, Matt1969 said:

20200921_170306.jpg

Looking at your photo!

1) Your out put hose to PRV looks to be under tension? Needs to have slack in it.

2) There also appears to be no markings on the Jacket of the hose? What is the psi of your hose?

3) Fuel supply from tank to filter what is the bore size of your hose s/b 12m/m?

4) Noise when low on fuel means not enough fuel flow to pump!

Bruce.

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It makes a noise, full or empty.  Seems to be worse in hot weather and if I take out all the stuff from the boot, its better, assume as it's cooler.

Waldi - The pump is a Bosch 0 580 254 941  Next line 12V (illegible) 520-25

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Matt,

I looked up the flow rate of your pump:
It shows a rated flow of 150 ltr/min @ 7,2 (around 105 psi) bar and a current draw of 10-11 A, see below.
Almost twice  that of the original Lucas pump, both in flowrate and current. 
There are better suitable Bosch pumps available, which have a lower flow and curve.
This will reduce cavitation (suction side), harmonic vibrations (discharge side).

I ordered a new Bosch 126 pump, it costed around 100 euro over here, next day delivery from my automotive parts supplier.
Also, I would measure the fuel temperature if the issue occurs, I used and IR gun that I pointed in the tank.
Make sure you measure already before entering the gun nose in the tank, so no sparks develop.
Mine (and most on the market) is not Ex-proof!

 


image.png.3d019bad737c9788e5601e94f5c5cf68.png
 

Not sure if I shared before on this forum; I lcompared specifications of several Bosch pumps and below are some,  do not order the 0580.254.044.
Is is just mentioned because it can be confused with the other "044"pump also listed.

image.thumb.png.2d17b412b30d45f3390ca286dd242ca5.png.

Waldi.

 

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Thanks Waldi, that is very useful.  I couldnt find the flow rates anywhere.  So you think I need a Bosch 0580 464 126?  Theyt seem to be around £ 70 online.

Edited by Matt1969
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No problem Matt.

Is a .126 pump “the“ answer? Well,...

At 30 degrees ambient my fuel temperature rose quickly to 30+ degrees, within 60 km a 9 degree C rise (but it did not stop nor cavitate. So it is not perfect. I tested a cheap PWM control, the pump started making irregular noise, so I stopped that but was able to control pump speed anOn the German forum are 1 or 2 people driving with PWM, they are happy with it. Maybe better quality item. This will reduce flowrate and current a bit.

The 126 pump is a relatively cheap pump with a not too bad pump curve.

And off course: each to his own;)

Waldi

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