| Author | Message | ||
     David Turner New User Username: silver_spur Post Number: 10 Registered: 11-2006 |
bothering me now for some time, My 88 spur has a buzzing noise which can be heard inside the car when at idle it can be heard above the radio . with a stethascope it can be isolated to the fuel return line and on up to the frequency valve. the valve itself does not seem any louder than those on many other cars, mostly mercedes-benz i have owned, but i think due to the fact that the fuel lines run below my footwell i can hear them . i had a good look at the lines and all looks in order with the lines supported in the originalrubber and not damaged or touching the body anywhere. any thoughts anyone. thanks Dave | ||
| StevenBrown Experienced User Username: stevenbrown Post Number: 21 Registered: 10-2008 |
I know that RR offered a hush kit on fuel pumps that make a buzzing noise. Forget what years, etcetera that this occurs. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1520 Registered: 4-2003 |
Note that these early fuel injected systems tend to become noisy once the fuel tank level falls low enough for the fuel warning lamp to flash. The noise is caused by the return flow to the tank from the recirculation fuel supply system. With a low tank level, the returned fuel squirts back into the tank above the fuel level. For some other cases, the RH3009 fuel pump noise reduction kit and fitting are shown in: www.rrtechnical.info/sz/sz87/pumpnoise/fuelpumpnoisereduction.pdf Note that the pre-pump is deleted. The kit is probably a long-gone offering from Crewe, but the description may show enough for an enterprising hobbyist to implement. RT. | ||
| David Turner Experienced User Username: silver_spur Post Number: 11 Registered: 11-2006 |
my car already had the hush kit fitted some long time ago.i have spent the day thinking and tinkering. For sure, the noise comes from the return side at all tank levels and will completely dissapear if i disconect the electrical conector from the frequency valve, Thoughts are that the rubber mounts which are 20 years old may have become hard and now transfer the noise as if the pipe were mounted solidly. i will pull them off and have a look. on the subject of quieting kits ,Mercedes-Benz used to use a rubber return hose on diesel models that appeared swolen, it was very sucsessful at quieting the noise on those cars and would be simple to fit into the return. i will fiddle for a bit this week. thanks for the thoughts dave | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1522 Registered: 4-2003 |
In that case, it sounds like a dud fuel accumulator or a dud fuel pressure damper to me, neither of which are electrical of course. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1523 Registered: 4-2003 |
Forget your susbstitute squishy gummihoses for Berlin diesel taxis, tractors and the like. Devising such fiddles assumes that there is an inherent defect, and there is not. | ||
| David Turner Experienced User Username: silver_spur Post Number: 12 Registered: 11-2006 |
Thanks for puting me back on track.you are correct in that there is probably no inherant defect. I checked the rubber mounts for the pipework and they appear in good and flexible condition but there is a length of rubber hose in the return line next to the fuel filter ,and it feels like it has turned to stone , looking at the parts diagram there are 4 or 5 such 6" lenghts so i will change them all and pehaps some restored flexability is all i need. The accumulator and damper are in the feed side so i doubt they are the culprits , i do know that i have no rest presure or hot start problems and no fuel leaks by the accumulator diaphragm , i dont know how you would test the little damper. i will stay away from the M/B taxi parts . regards Dave | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1035 Registered: 4-2003 |
Back to the frequency valve. As I remember it is a Bosch Electronic Fuel Injector and it is not unusual for them to become partially blocked. The best way to clean them is in an ultra sonic bath as with all electronic injectors! Can I also suggest checking the intank filter - often forgotten. I think there is a relevant picture on R. A.Chapman's web site www.rachapmanautomotive.com.au | ||
| David Turner Experienced User Username: silver_spur Post Number: 13 Registered: 11-2006 |
thanks bill ,that realy is an ugly picture of a filter,but it is also located on the feed side of the system i would think it would lead to pump noise due to not enough supply. I have just come in from the garage where i changed 3 of the rubber fuel hoses that connect the metal pipe work , after changing the first one which is next to the fuel filter and therefore directly below my footwell and aprox 6 inches long,i thought i could detect a reduction but it may have been wishfull thinking. the next one towards the rear of the car and approx 9 inches long and there was a great improvement, after swaping the third one the noise was almost impossible to detect. So looks like problem solved. Now i have to confess i went back to the longer hose and swaped it for the "berlin taxi" part and i think there was another small impovement, perhaps not but i will leave it in anyway, justifying it as the rest of the system came from the Germans anyway. I now have a full tank of fuel but once its gone i will remove that filter fom the tank if it proves to be interesting i will post a picture. best regards to all Dave |
