raydrink Posted May 2, 2007 Report Share Posted May 2, 2007 Now the car is running OK, I am more confident about taking it on longer journeys but I am now noticing that after about an hour's driving the Bosch fuel pump is making intermittent noises like a bearing has failed. My initial though was that it may be caused by the head of fuel being low as I was down to about quarter tank, but yesterday it continued after filling to three quarters. There is no loss of power, it continues to drive smoothly and pulls fine. Motorway speeds are still OK (when I assume most fuel is being demanded from the pump). So I would be grateful to know if I should ignore it on the basis that if it ain't broke don't fix it, or should I be thinking that the pump is telling me that its days are numbered and that I should be carrying a spare? I felt the pump when I arrived home last night and it was barely warm, but as luck would have it, the noise stopped so if someone wants to suggest it is the PRV, I wouldn't argue! Any help greatly appreciated. Ray Quote Link to post Share on other sites
Richard Crawley Posted May 2, 2007 Report Share Posted May 2, 2007 I reakon it could either be the PRV or resonance in the fuel line. Both have cropped up before so there are archive posts on both topics. Quote Link to post Share on other sites
badshead Posted May 2, 2007 Report Share Posted May 2, 2007 Ray The noise of the Bosch pump is usually only audible with the engine off, plus noise when it's warmed up suggests either the pump is getting tired, gravity fed fuel supply is inadequate or maybe pressure is too high and the pump is working harder than it should. Suggest you replace pre and post fuel filters, test fuel pressure and check fuel return from MRU to petrol tank is clear - also check you've got the larger bore feed from the fuel tank recommended for the Bosch pump. Quote Link to post Share on other sites
Maregratia Posted May 2, 2007 Report Share Posted May 2, 2007 I reakon it could either be the PRV or resonance in the fuel line. Both have cropped up before so there are archive posts on both topics. Had this problem with my prv. some days only just hear the pump other times noise was so bad it sounded as if the horn was stuck on. Spoke to Malcom at Prestige Development and Injection who told me it was most likely to be the spring in the prv vibrating in the housing. He suggested a mod of having the prv body drilled out and a sleave fitted around the spring or he has modified diaphram prv to replace the original not cheep at £82.00 but imediately solved my problem and had a peacefull life since. John TR6 Quote Link to post Share on other sites
pinky Posted May 3, 2007 Report Share Posted May 3, 2007 I had this problem last night it was like a whistling noise as luck would have it I had the back all stripped out so I had a little fiddle as you do, lifting and moving the flexible fuel pipe changed the pitch and volume could almost play a tune, any way I packed the pipe out with a bath sponge this stopped the noise completely however the trouble and strive was a bit p---d of pinching g her sponge so I ended up having to wash her back hope this helps pinky Quote Link to post Share on other sites
raydrink Posted June 7, 2007 Author Report Share Posted June 7, 2007 Just for completeness, in case anyone is suffering with the same issue (or may do in the future) this is where I'm up to with this problem. Firstly let me say that the pump noise I am getting after an hour-ish of driving is only that of ground glass (whirring) not the noise described variously as a horn stuck on, whistling etc which I only get when the ignition is switched on and I believe is related to the PRV getting up to pressure. I've no issues with harmonics in the pipes. I've cleaned both filters (the pre was virtually brand new anyway), checked the fuel pressure and listened to the fuel returning into the tank. These things made no difference. However, it occured to me that I usually start a lengthy drive with a resonably full tank so that after a decent drive there is usually less than half a tank left - this is when the noise starts. So this week, when the noise started I dived into a filling station and filled up. When I set off the noise was gone. So it looks like the pump is susceptible to the head of fuel above it, leaving me to ponder - still - if the pump is letting me know that it's on its last legs. It is already sited at the lowest point in the boot so perhaps I'll buy a spare pump and carry it with me. thanks to all who offered advice, gratefully received as always. Ray Quote Link to post Share on other sites
jonlar Posted June 8, 2007 Report Share Posted June 8, 2007 Hi Ray, after driving for an hour or so and the pump is making a noise, try seeing how warm the petrol tank feels to the touch - as fuel is used as a coolant and excess is returned it could be the fuel is vapourising and caused cavitation? Quote Link to post Share on other sites
jr.clarkson Posted June 11, 2007 Report Share Posted June 11, 2007 Hi Ray, after driving for an hour or so and the pump is making a noise, try seeing how warm the petrol tank feels to the touch - as fuel is used as a coolant and excess is returned it could be the fuel is vapourising and caused cavitation? Hi Ray as Jonlar said, check the fuel temp. I have just fitted a Bosch unit after my third Lucas up and died. I have used the original CAV filter but had real problems with the temp of the fuel and the pump, made a horrible noise, almost like it was cavitating. I had plumbed the return from the PRV to the fuel suply and was pumping hot fuel back to the pump. Once I plumbed back to the tank, cold fuel and no noise. Once you have all stopped laughing..... luckily a cheap mistake, no damage this time. Cheers John Quote Link to post Share on other sites
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